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Data Encoding: Non-Standard Encoding
Other sub-techniques of Data Encoding (2)
| ID | Name |
|---|---|
| T1132.001 | Standard Encoding |
| T1132.002 | Non-Standard Encoding |
Adversaries may encode data with a non-standard data encoding system to make the content of command and control traffic more difficult to detect. Command and control (C2) information can be encoded using a non-standard data encoding system that diverges from existing protocol specifications. Non-standard data encoding schemes may be based on or related to standard data encoding schemes, such as a modified Base64 encoding for the message body of an HTTP request.[1] [2]
Procedure Examples
| Name | Description |
|---|---|
| BACKSPACE |
Newer variants of BACKSPACE will encode C2 communications with a custom system.[4] |
| Bankshot |
Bankshot encodes commands from the control server using a range of characters and gzip.[5] |
| OceanSalt |
OceanSalt can encode data with a NOT operation before sending the data to the control server.[3] |
Mitigations
| Mitigation | Description |
|---|---|
| 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 obfuscation technique 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. |
Detection
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.[6]
References
- Wikipedia. (2016, December 26). Binary-to-text encoding. Retrieved March 1, 2017.
- Wikipedia. (2017, February 19). Character Encoding. Retrieved March 1, 2017.
- Sherstobitoff, R., Malhotra, A. (2018, October 18). ‘Operation Oceansalt’ Attacks South Korea, U.S., and Canada With Source Code From Chinese Hacker Group. Retrieved November 30, 2018.
- FireEye Labs. (2015, April). APT30 AND THE MECHANICS OF A LONG-RUNNING CYBER ESPIONAGE OPERATION. Retrieved May 1, 2015.
- Sherstobitoff, R. (2018, March 08). Hidden Cobra Targets Turkish Financial Sector With New Bankshot Implant. Retrieved May 18, 2018.
- Gardiner, J., Cova, M., Nagaraja, S. (2014, February). Command & Control Understanding, Denying and Detecting. Retrieved April 20, 2016.