Python One-Liners with Base64 Decoding

A Sigma rule for process creation on Windows, by Hugh Ryan (HueCodes), Swachchhanda Shrawan Poudel (Nextron Systems).

high 2 ATT&CK techniques

What it looks for

its detection, as SigmaHQ writes it

detection:
  selection_cli:
    CommandLine|contains:
      - '.decode'
      - 'b16decode'
      - 'b32decode'
      - 'b32hexdecode'
      - 'b64decode'
      - 'b85decode'
      - 'z85decode'
    CommandLine|contains|all:
      - 'import'
      - 'base64'
      - ' -c'
  selection_img:
    - Image|contains: '\python'
    - OriginalFileName|contains: 'python'
  condition: all of selection_*

The rule’s detection, its selections and fields in order of name. The whole rule, with its references and false positives, is on SigmaHQ, by Hugh Ryan (HueCodes), Swachchhanda Shrawan Poudel (Nextron Systems), under the Detection Rule License 1.1. CmdID evaluates it on a command line alone: a test on what a command line cannot show, such as the parent process or the user, is not met.

None of the everyday examples and documented commands on CmdID’s program pages trips it. To see whether a command line does, paste it into CmdID.

ATT&CK

the techniques it is tagged with

T1027.010Obfuscated Files or Information: Command Obfuscation

T1059.006Command and Scripting Interpreter: Python

Python One-Liners with Base64 Decoding

What it looks for

ATT&CK

Other rules for T1027.010 Obfuscated Files or Information: Command Obfuscation