Suspicious Script Object Execution

Identifies scrobj.dll loaded into unusual Microsoft processes. This usually means a malicious scriptlet is being executed in the target process.

Rule type: eql

Rule indices:

logs-endpoint.events.*

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

Tags:

Elastic
Host
Windows
Threat Detection
Defense Evasion

Version: 4 (version history)

Added (Elastic Stack release): 7.10.0

Last modified (Elastic Stack release): 7.13.0

Rule authors: Elastic

Rule license: Elastic License v2

Rule query

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sequence by process.entity_id with maxspan=2m [process where
event.type == "start" and (process.code_signature.subject_name in
("Microsoft Corporation", "Microsoft Windows") and
process.code_signature.trusted == true) and not
process.executable : ( "?:\\Windows\\System32\\cscript.exe",
"?:\\Windows\\SysWOW64\\cscript.exe", "?:\\Program Files
(x86)\\Internet Explorer\\iexplore.exe", "?:\\Program
Files\\Internet Explorer\\iexplore.exe", "?:\\Windows\\SystemAp
ps\\Microsoft.MicrosoftEdge_*\\MicrosoftEdge.exe",
"?:\\Windows\\system32\\msiexec.exe",
"?:\\Windows\\SysWOW64\\msiexec.exe",
"?:\\Windows\\System32\\smartscreen.exe",
"?:\\Windows\\system32\\taskhostw.exe",
"?:\\windows\\system32\\inetsrv\\w3wp.exe",
"?:\\windows\\SysWOW64\\inetsrv\\w3wp.exe",
"?:\\Windows\\system32\\wscript.exe",
"?:\\Windows\\SysWOW64\\wscript.exe",
"?:\\Windows\\system32\\mobsync.exe",
"?:\\Windows\\SysWOW64\\mobsync.exe",
"?:\\Windows\\System32\\cmd.exe",
"?:\\Windows\\SysWOW64\\cmd.exe")] [library where event.type ==
"start" and dll.name : "scrobj.dll"]

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: Signed Binary Proxy Execution
- ID: T1218
- Reference URL: https://attack.mitre.org/techniques/T1218/

Rule version history

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Version 4 (7.13.0 release)

Rule name changed from: Windows Suspicious Script Object Execution

Updated query, changed from:

/* add winlogbeat-* when process.code_signature.* fields are populated
*/ sequence by process.entity_id with maxspan = 2m [process where
event.type in ("start", "process_started") and /* uncomment once
in winlogbeat */ /* process.code_signature.subject_name :
"Microsoft Corporation" and process.code_signature.trusted : true and
*/ not process.name : ( "cscript.exe",
"iexplore.exe", "MicrosoftEdge.exe", "msiexec.exe",
"smartscreen.exe", "taskhostw.exe", "w3wp.exe",
"wscript.exe")] [library where event.type == "start" and dll.name :
"scrobj.dll"]

Version 3 (7.12.0 release)

Updated query, changed from:

/* add winlogbeat-* when process.code_signature.* fields are populated
*/ sequence by process.entity_id with maxspan=2m [process where
event.type in ("start", "process_started") and /* uncomment once
in winlogbeat */ /* process.code_signature.subject_name ==
"Microsoft Corporation" and process.code_signature.trusted == true and
*/ not (process.name : "cscript.exe" or process.name :
"iexplore.exe" or process.name : "MicrosoftEdge.exe" or
process.name : "msiexec.exe" or process.name :
"smartscreen.exe" or process.name : "taskhostw.exe" or
process.name : "w3wp.exe" or process.name : "wscript.exe")]
[library where event.type == "start" and file.name : "scrobj.dll"]

Version 2 (7.11.0 release)

Formatting only

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