Data Obfuscation: Junk Data
Adversaries may add junk data to protocols used for command and control to make detection more difficult. By adding random or meaningless data to the protocols used for command and control, adversaries can prevent trivial methods for decoding, deciphering, or otherwise analyzing the traffic. Examples may include appending/prepending data with junk characters or writing junk characters between significant characters.
APT28 added "junk data" to each encoded string, preventing trivial decoding without knowledge of the junk removal algorithm. Each implant was given a "junk length" value when created, tracked by the controller software to allow seamless communication but prevent analysis of the command protocol on the wire.
|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 some obfuscation activity at the network level.
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.
- FireEye. (2015). APT28: A WINDOW INTO RUSSIA’S CYBER ESPIONAGE OPERATIONS?. Retrieved August 19, 2015.
- ESET. (2016, October). En Route with Sednit - Part 3: A Mysterious Downloader. Retrieved November 21, 2016.
- SecureWorks. (2013). The Lifecycle of Peer-to-Peer (Gameover) ZeuS. Retrieved August 19, 2015.
- Cherepanov, A.. (2018, July 9). Certificates stolen from Taiwanese tech‑companies misused in Plead malware campaign. Retrieved May 6, 2020.
- CISA. (2020, July 16). MAR-10296782-2.v1 – WELLMESS. Retrieved September 24, 2020.
- Gardiner, J., Cova, M., Nagaraja, S. (2014, February). Command & Control Understanding, Denying and Detecting. Retrieved April 20, 2016.