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T1090.002 External Proxy

Adversaries may use an external proxy to act as an intermediary for network communications to a command and control server to avoid direct connections to their infrastructure. Many tools exist that enable traffic redirection through proxies or port redirection, including HTRAN, ZXProxy, and ZXPortMap. 1 Adversaries use these types of proxies to manage command and control communications, to provide resiliency in the face of connection loss, or to ride over existing trusted communications paths to avoid suspicion.

External connection proxies are used to mask the destination of C2 traffic and are typically implemented with port redirectors. Compromised systems outside of the victim environment may be used for these purposes, as well as purchased infrastructure such as cloud-based resources or virtual private servers. Proxies may be chosen based on the low likelihood that a connection to them from a compromised system would be investigated. Victim systems would communicate directly with the external proxy on the Internet and then the proxy would forward communications to the C2 server.

Item Value
ID T1090.002
Sub-techniques T1090.001, T1090.002, T1090.003, T1090.004
Tactics TA0011
Platforms Linux, Windows, macOS
Version 1.0
Created 14 March 2020
Last Modified 27 March 2020

Procedure Examples

ID Name Description
G0007 APT28 APT28 used other victims as proxies to relay command traffic, for instance using a compromised Georgian military email server as a hop point to NATO victims. The group has also used a tool that acts as a proxy to allow C2 even if the victim is behind a router. APT28 has also used a machine to relay and obscure communications between CHOPSTICK and their server.202122
G0022 APT3 An APT3 downloader establishes SOCKS5 connections for its initial C2.28
G0087 APT39 APT39 has used various tools to proxy C2 communications.15
G0053 FIN5 FIN5 maintains access to victim environments by using FLIPSIDE to create a proxy for a backup RDP tunnel.23
G0093 GALLIUM GALLIUM used a modified version of HTRAN to redirect connections between networks.27
S0260 InvisiMole InvisiMole InvisiMole can identify proxy servers used by the victim and use them for C2 communication.910
G0032 Lazarus Group Lazarus Group has used multiple proxies to obfuscate network traffic from victims.1819
G0045 menuPass menuPass has used a global service provider’s IP as a proxy for C2 traffic from a victim.1617
G0069 MuddyWater MuddyWater has controlled POWERSTATS from behind a proxy network to obfuscate the C2 location.24 MuddyWater has used a series of compromised websites that victims connected to randomly to relay information to command and control (C2).2526
S0699 Mythic Mythic can leverage a modified SOCKS5 proxy to tunnel egress C2 traffic.3
S0439 Okrum Okrum can identify proxy servers configured and used by the victim, and use it to make HTTP requests to C2 its server.5
S0223 POWERSTATS POWERSTATS has connected to C2 servers through proxies.8
S0650 QakBot QakBot has a module that can proxy C2 communications.12
S0019 Regin Regin leveraged several compromised universities as proxies to obscure its origin.4
S0444 ShimRat ShimRat can use pre-configured HTTP proxies.11
G0091 Silence Silence has used ProxyBot, which allows the attacker to redirect traffic from the current node to the backconnect server via Sock4\Socks5.14
G0131 Tonto Team Tonto Team has routed their traffic through an external server in order to obfuscate their location.29
S0266 TrickBot TrickBot has been known to reach a command and control server via one of nine proxy IP addresses. 6 7
S0141 Winnti for Windows The Winnti for Windows HTTP/S C2 mode can make use of an external proxy.13

Mitigations

ID Mitigation Description
M1031 Network Intrusion Prevention Network intrusion detection and prevention systems that use network signatures to identify traffic for specific adversary malware can be used to mitigate activity at the network level. Signatures are often for unique indicators within protocols and may be based on the specific C2 protocol used by a particular adversary or tool, and will likely be different across various malware families and versions. Adversaries will likely change tool C2 signatures over time or construct protocols in such a way as to avoid detection by common defensive tools.2

Detection

ID Data Source Data Component
DS0029 Network Traffic Network Connection Creation

References

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  2. Gardiner, J., Cova, M., Nagaraja, S. (2014, February). Command & Control Understanding, Denying and Detecting. Retrieved April 20, 2016. ↩

  3. Thomas, C. (n.d.). Mythc Documentation. Retrieved March 25, 2022. ↩

  4. Kaspersky Lab’s Global Research and Analysis Team. (2014, November 24). THE REGIN PLATFORM NATION-STATE OWNAGE OF GSM NETWORKS. Retrieved December 1, 2014. ↩

  5. Hromcova, Z. (2019, July). OKRUM AND KETRICAN: AN OVERVIEW OF RECENT KE3CHANG GROUP ACTIVITY. Retrieved May 6, 2020. ↩

  6. Liviu Arsene, Radu Tudorica. (2020, November 23). TrickBot is Dead. Long Live TrickBot!. Retrieved September 28, 2021. ↩

  7. Radu Tudorica. (2021, July 12). A Fresh Look at Trickbot’s Ever-Improving VNC Module. Retrieved September 28, 2021. ↩

  8. Singh, S. et al.. (2018, March 13). Iranian Threat Group Updates Tactics, Techniques and Procedures in Spear Phishing Campaign. Retrieved April 11, 2018. ↩

  9. Hromcová, Z. (2018, June 07). InvisiMole: Surprisingly equipped spyware, undercover since 2013. Retrieved July 10, 2018. ↩

  10. Hromcova, Z. and Cherpanov, A. (2020, June). INVISIMOLE: THE HIDDEN PART OF THE STORY. Retrieved July 16, 2020. ↩

  11. Yonathan Klijnsma. (2016, May 17). Mofang: A politically motivated information stealing adversary. Retrieved May 12, 2020. ↩

  12. Kuzmenko, A. et al. (2021, September 2). QakBot technical analysis. Retrieved September 27, 2021. ↩

  13. Novetta Threat Research Group. (2015, April 7). Winnti Analysis. Retrieved February 8, 2017. ↩

  14. Group-IB. (2018, September). Silence: Moving Into the Darkside. Retrieved May 5, 2020. ↩

  15. Rusu, B. (2020, May 21). Iranian Chafer APT Targeted Air Transportation and Government in Kuwait and Saudi Arabia. Retrieved May 22, 2020. ↩

  16. FireEye iSIGHT Intelligence. (2017, April 6). APT10 (MenuPass Group): New Tools, Global Campaign Latest Manifestation of Longstanding Threat. Retrieved June 29, 2017. ↩

  17. Matsuda, A., Muhammad I. (2018, September 13). APT10 Targeting Japanese Corporations Using Updated TTPs. Retrieved September 17, 2018. ↩

  18. US-CERT. (2017, November 22). Alert (TA17-318A): HIDDEN COBRA – North Korean Remote Administration Tool: FALLCHILL. Retrieved December 7, 2017. ↩

  19. Mabutas, G. (2020, May 11). New MacOS Dacls RAT Backdoor Shows Lazarus’ Multi-Platform Attack Capability. Retrieved August 10, 2020. ↩

  20. FireEye. (2015). APT28: A WINDOW INTO RUSSIA’S CYBER ESPIONAGE OPERATIONS?. Retrieved August 19, 2015. ↩

  21. Bitdefender. (2015, December). APT28 Under the Scope. Retrieved February 23, 2017. ↩

  22. Mueller, R. (2018, July 13). Indictment - United States of America vs. VIKTOR BORISOVICH NETYKSHO, et al. Retrieved September 13, 2018. ↩

  23. Bromiley, M. and Lewis, P. (2016, October 7). Attacking the Hospitality and Gaming Industries: Tracking an Attacker Around the World in 7 Years. Retrieved October 6, 2017. ↩

  24. Symantec DeepSight Adversary Intelligence Team. (2018, December 10). Seedworm: Group Compromises Government Agencies, Oil & Gas, NGOs, Telecoms, and IT Firms. Retrieved December 14, 2018. ↩

  25. Reaqta. (2017, November 22). A dive into MuddyWater APT targeting Middle-East. Retrieved May 18, 2020. ↩

  26. Peretz, A. and Theck, E. (2021, March 5). Earth Vetala – MuddyWater Continues to Target Organizations in the Middle East. Retrieved March 18, 2021. ↩

  27. Cybereason Nocturnus. (2019, June 25). Operation Soft Cell: A Worldwide Campaign Against Telecommunications Providers. Retrieved July 18, 2019. ↩

  28. Moran, N., et al. (2014, November 21). Operation Double Tap. Retrieved January 14, 2016. ↩

  29. Daniel Lughi, Jaromir Horejsi. (2020, October 2). Tonto Team - Exploring the TTPs of an advanced threat actor operating a large infrastructure. Retrieved October 17, 2021. ↩

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