Suspicious Execution from a Mounted Device

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Identifies when a script interpreter or signed binary is launched via a non-standard working directory. An attacker may use this technique to evade defenses.

Rule type: eql

Rule indices:

  • winlogbeat-*
  • logs-endpoint.events.*
  • logs-windows.*

Severity: medium

Risk score: 47

Runs every: 5 minutes

Searches indices from: now-9m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

References:

Tags:

  • Elastic
  • Host
  • Windows
  • Threat Detection
  • Defense Evasion

Version: 1

Added (Elastic Stack release): 7.14.0

Rule authors: Elastic

Rule license: Elastic License v2

Rule query

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process where event.type == "start" and process.executable : "C:\\*"
and (process.working_directory : "?:\\" and not
process.working_directory: "C:\\") and process.parent.name :
"explorer.exe" and process.name : ("rundll32.exe", "mshta.exe",
"powershell.exe", "pwsh.exe", "cmd.exe", "regsvr32.exe",
"cscript.exe", "wscript.exe")

Threat mapping

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Framework: MITRE ATT&CKTM