CmdID / Rules / Windows

Shai-Hulud Malicious Bun Execution

A Sigma rule for process creation on Windows, from SigmaHQ’s emerging threats rules, by Swachchhanda Shrawan Poudel (Nextron Systems).

high 2 ATT&CK techniques

What it looks for

its detection, as SigmaHQ writes it

detection:
  selection_child_bun_script:
    CommandLine|contains:
      - 'bun_environment.js'
      - 'https://github.com/actions/runner/releases/download/v2.330.0'
    Image|endswith: '\bun.exe'
  selection_parent:
    ParentImage|endswith: '\node.exe'
  condition: selection_parent and 1 of selection_child_*

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 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

T1195.002Supply Chain Compromise: Compromise Software Supply Chain

T1203Exploitation for Client Execution

Shai-Hulud Malicious Bun Execution

What it looks for

ATT&CK

Other rules for T1195.002 Supply Chain Compromise: Compromise Software Supply Chain