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Suspicious Execution from a Mounted Device

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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: 100 (version history)

Added (Elastic Stack release): 7.14.0

Last modified (Elastic Stack release): 8.5.0

Rule authors: Elastic

Rule license: Elastic License v2

Investigation guide

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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&CK^TM

Tactic:
- Name: Defense Evasion
- ID: TA0005
- Reference URL: https://attack.mitre.org/tactics/TA0005/
Technique:
- Name: System Binary Proxy Execution
- ID: T1218
- Reference URL: https://attack.mitre.org/techniques/T1218/
Tactic:
- Name: Execution
- ID: TA0002
- Reference URL: https://attack.mitre.org/tactics/TA0002/
Technique:
- Name: Command and Scripting Interpreter
- ID: T1059
- Reference URL: https://attack.mitre.org/techniques/T1059/

Rule version history

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Version 100 (8.5.0 release)

Formatting only

Version 4 (8.4.0 release)

Formatting only

Version 2 (8.2.0 release)

Formatting only

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