Data Encoding: Non-Standard Encoding

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]

ID: T1132.002
Sub-technique of:  T1132
Tactic: Command And Control
Platforms: Linux, Windows, macOS
Permissions Required: User
Data Sources: Network protocol analysis, Packet capture, Process monitoring, Process use of network
Version: 1.0
Created: 14 March 2020
Last Modified: 14 March 2020

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