Custom Command and Control Protocol
|Custom Command and Control Protocol|
|Tactic||Command and Control|
|Platform||Linux, macOS, Windows|
|Data Sources||Packet capture, Netflow/Enclave netflow, Process use of network, Process monitoring|
Adversaries may communicate using a custom command and control protocol instead of using existing Standard Application Layer Protocol to encapsulate commands. Implementations could mimic well-known protocols.
- APT32 uses Cobalt Strike's malleable C2 functionality to blend in with network traffic.12
- Lazarus Group malware uses a unique form of communication encryption that mimics TLS but uses a different encryption method, evading SSL man-in-the-middle decryption attacks.3
- OilRig has used custom DNS Tunneling protocols for C2.4
- Cobalt Strike allows adversaries to modify the way the "beacon" payload communicates. This is called "Malleable C2" in the Cobalt Strike manual and is intended to allow a penetration test team to mimic known APT C2 methods.52
- Duqu is capable of using its command and control protocol over port 443. However, Duqu is also capable of encapsulating its command protocol over standard application layer protocols. The Duqu command and control protocol implements many of the same features as TCP and is a reliable transport protocol.6
- RTM uses HTTP POST requests with data formatted using a custom protocol.7
- RedLeaves can communicate to its C2 over TCP using a custom binary protocol.8
- Volgmer uses a custom binary protocol to beacon back to its C2 server.9
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 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.10
Analyze network data for uncommon data flows (e.g., a client sending significantly more data than it receives from a server). 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.10
- Carr, N.. (2017, May 14). Cyber Espionage is Alive and Well: APT32 and the Threat to Global Corporations. Retrieved June 18, 2017.
- Mudge, R. (2014, July 14). Github Malleable-C2-Profiles safebrowsing.profile. Retrieved June 18, 2017.
- Novetta Threat Research Group. (2016, February 24). Operation Blockbuster: Unraveling the Long Thread of the Sony Attack. Retrieved February 25, 2016.
- Unit 42. (2017, December 15). Unit 42 Playbook Viewer - Oil Rig. Retrieved December 20, 2017.
- 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.
- Faou, M. and Boutin, J.. (2017, February). Read The Manual: A Guide to the RTM Banking Trojan. Retrieved March 9, 2017.
- FireEye iSIGHT Intelligence. (2017, April 6). APT10 (MenuPass Group): New Tools, Global Campaign Latest Manifestation of Longstanding Threat. Retrieved June 29, 2017.
- US-CERT. (2017, November 22). Alert (TA17-318B): HIDDEN COBRA – North Korean Trojan: Volgmer. Retrieved December 7, 2017.
- Gardiner, J., Cova, M., Nagaraja, S. (2014, February). Command & Control Understanding, Denying and Detecting. Retrieved April 20, 2016.