CmdID

CmdID / Rules / Windows

Arbitrary File Download Via Squirrel.EXE

A Sigma rule for process creation on Windows, by Nasreddine Bencherchali (Nextron Systems), Karneades / Markus Neis, Jonhnathan Ribeiro, oscd.community.

medium 1 ATT&CK technique 2 programs it names

What it looks for

its detection, as SigmaHQ writes it
detection:
  selection_download_cli:
    CommandLine|contains:
      - ' --download '
      - ' --update '
      - ' --updateRollback='
  selection_download_http_keyword:
    CommandLine|contains: 'http'
  selection_img:
    Image|endswith:
      - '\squirrel.exe'
      - '\update.exe'
  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 Nasreddine Bencherchali (Nextron Systems), Karneades / Markus Neis, Jonhnathan Ribeiro, oscd.community, 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.

Command lines that trip it

documented abuse, read by CmdID

The commands documented for squirrel.exe, update.exe trip it: each is on its program’s page, read by CmdID.

Programs and files it names

their pages here
squirrel.exeupdate.exe

ATT&CK

the techniques it is tagged with
T1218System Binary Proxy Execution

Other rules for T1218 System Binary Proxy Execution

Suspicious AddinUtil.EXE CommandLine Execution · Uncommon Child Process Of AddinUtil.EXE · Uncommon AddinUtil.EXE CommandLine Execution · AddinUtil.EXE Execution From Uncommon Directory · AgentExecutor PowerShell Execution · Suspicious AgentExecutor PowerShell Execution · Uncommon Child Process Of Appvlp.EXE · Uncommon Assistive Technology Applications Execution Via AtBroker.EXE · BitLockerTogo.EXE Execution · DLL Loaded via CertOC.EXE · Suspicious DLL Loaded via CertOC.EXE · Potential NTLM Coercion Via Certutil.EXE