|Tactic||Command and Control|
|Platform||Linux, macOS, Windows|
|Data Sources||Process use of network, Process monitoring, Netflow/Enclave netflow, Packet capture, Process monitoring|
A connection proxy is used to direct network traffic between systems or act as an intermediary for network communications. Many tools exist that enable traffic redirection through proxies or port redirection, including HTRAN, ZXProxy, and ZXPortMap.1
The definition of a proxy can also be expanded out to encompass trust relationships between networks in peer-to-peer, mesh, or trusted connections between networks consisting of hosts or systems that regularly communicate with each other.
The network may be within a single organization or across organizations with trust relationships. Adversaries could use these types of relationships to manage command and control communications, to reduce the number of simultaneous outbound network connections, to provide resiliency in the face of connection loss, or to ride over existing trusted communications paths between victims to avoid suspicion.
- 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.2 The group has also used a tool that acts as a proxy to allow C2 even if the victim is behind a router.3
- Lazarus Group uses multiple proxies to obfuscate network traffic from victims.4
- Strider has used local servers with both local network and Internet access to act as internal proxy nodes to exfiltrate data from other parts of the network without direct Internet access.5
- menuPass has used a global service provider's IP as a proxy for C2 traffic from a victim.6
- The "ZJ" variant of BACKSPACE allows "ZJ link" infections with Internet access to relay traffic from "ZJ listen" to a command server.7
- CHOPSTICK used a proxy server between victims and the C2 server.8
- Cobalt Strike can be configured to have commands relayed over a peer-to-peer network of infected hosts. This can be used to limit the number of egress points, or provide access to a host without direct internet access.9
- Duqu can be configured to have commands relayed over a peer-to-peer network of infected hosts if some of the hosts do not have Internet access.10
- FLIPSIDE is a simple proxy that creates an outbound RDP connection.11
- Gazer identifies a proxy server if it exists and uses it to make HTTP requests.12
- HTRAN is used for proxying connections to obfuscate command and control infrastructure.13
- Hikit supports peer connections.14
- Regin leveraged several compromised universities as proxies to obscure its origin.15
- XTunnel relays traffic between a C2 server and a victim.16
- netsh can be used to set up a proxy tunnel to allow remote host access to an infected host.17
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.18
Processes utilizing the network that do not normally have network communication or have never been seen before are suspicious. Network activities disassociated from user-driven actions from processes that normally require user direction are suspicious.
Analyze network data for uncommon data flows (e.g., a client sending significantly more data than it receives from a server or between clients that should not or often do not communicate with one another). Processes utilizing the network that do not normally have network communication or have never been seen before are suspicious. Analyze packet contents to detect communications that do not follow the expected protocol behavior for the port that is being used.18
- Wilhoit, K. (2013, March 4). In-Depth Look: APT Attack Tools of the Trade. Retrieved December 2, 2015.
- FireEye. (2015). APT28: A WINDOW INTO RUSSIA’S CYBER ESPIONAGE OPERATIONS?. Retrieved August 19, 2015.
- Bitdefender. (2015, December). APT28 Under the Scope. Retrieved February 23, 2017.
- US-CERT. (2017, November 22). Alert (TA17-318A): HIDDEN COBRA – North Korean Remote Administration Tool: FALLCHILL. Retrieved December 7, 2017.
- Kaspersky Lab's Global Research & Analysis Team. (2016, August 8). ProjectSauron: top level cyber-espionage platform covertly extracts encrypted government comms. Retrieved August 17, 2016.
- FireEye iSIGHT Intelligence. (2017, April 6). APT10 (MenuPass Group): New Tools, Global Campaign Latest Manifestation of Longstanding Threat. Retrieved June 29, 2017.
- FireEye Labs. (2015, April). APT30 AND THE MECHANICS OF A LONG-RUNNING CYBER ESPIONAGE OPERATION. Retrieved May 1, 2015.
- ESET. (2016, October). En Route with Sednit - Part 2: Observing the Comings and Goings. Retrieved November 21, 2016.
- Strategic Cyber LLC. (2017, March 14). Cobalt Strike Manual. Retrieved May 24, 2017.
- Symantec Security Response. (2011, November). W32.Duqu: The precursor to the next Stuxnet. Retrieved September 17, 2015.
- 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.
- ESET. (2017, August). Gazing at Gazer: Turla’s new second stage backdoor. Retrieved September 14, 2017.
- Haq, T., Moran, N., Vashisht, S., Scott, M. (2014, September). OPERATION QUANTUM ENTANGLEMENT. Retrieved November 4, 2015.
- Novetta. (n.d.). Operation SMN: Axiom Threat Actor Group Report. Retrieved November 12, 2014.
- Kaspersky Lab's Global Research and Analysis Team. (2014, November 24). THE REGIN PLATFORM NATION-STATE OWNAGE OF GSM NETWORKS. Retrieved December 1, 2014.
- Alperovitch, D.. (2016, June 15). Bears in the Midst: Intrusion into the Democratic National Committee. Retrieved August 3, 2016.
- Kaspersky Lab's Global Research and Analysis Team. (2017, February 8). Fileless attacks against enterprise networks. Retrieved February 8, 2017.
- Gardiner, J., Cova, M., Nagaraja, S. (2014, February). Command & Control Understanding, Denying and Detecting. Retrieved April 20, 2016.