Adversaries may use an existing, legitimate external Web service as a means for relaying data to/from a compromised system. Popular websites and social media acting as a mechanism for C2 may give a significant amount of cover due to the likelihood that hosts within a network are already communicating with them prior to a compromise. Using common services, such as those offered by Google or Twitter, makes it easier for adversaries to hide in expected noise. Web service providers commonly use SSL/TLS encryption, giving adversaries an added level of protection.
Use of Web services may also protect back-end C2 infrastructure from discovery through malware binary analysis while also enabling operational resiliency (since this infrastructure may be dynamically changed).
|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.
|Restrict Web-Based Content||
Web proxies can be used to enforce external network communication policy that prevents use of unauthorized external services.
Host data that can relate unknown or suspicious process activity using a network connection is important to supplement any existing indicators of compromise based on malware command and control signatures and infrastructure or the presence of strong encryption. Packet capture analysis will require SSL/TLS inspection if data is encrypted. Analyze network data for uncommon data flows (e.g., a client sending significantly more data than it receives from a server). User behavior monitoring may help to detect abnormal patterns of activity.
- Cycraft. (2020, April 15). APT Group Chimera - APT Operation Skeleton key Targets Taiwan Semiconductor Vendors. Retrieved August 24, 2020.
- McKeague, B. et al. (2019, April 5). Pick-Six: Intercepting a FIN6 Intrusion, an Actor Recently Tied to Ryuk and LockerGoga Ransomware. Retrieved April 17, 2019.
- Boutin, J. (2020, June 11). Gamaredon group grows its game. Retrieved June 16, 2020.
- GReAT. (2014, December 10). Cloud Atlas: RedOctober APT is back in style. Retrieved May 8, 2020.
- Symantec. (2018, March 14). Inception Framework: Alive and Well, and Hiding Behind Proxies. Retrieved May 8, 2020.
- Cimpanu, C. (2018, September 13). Sly malware author hides cryptomining botnet behind ever-shifting proxy service. Retrieved September 15, 2020.
- Anomali Labs. (2019, March 15). Rocke Evolves Its Arsenal With a New Malware Family Written in Golang. Retrieved April 24, 2019.
- Liebenberg, D.. (2018, August 30). Rocke: The Champion of Monero Miners. Retrieved May 26, 2020.
- Gardiner, J., Cova, M., Nagaraja, S. (2014, February). Command & Control Understanding, Denying and Detecting. Retrieved April 20, 2016.