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: 5m

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

Maximum alerts per execution: 100

References: None

Tags:

Elastic
Host
Windows
Threat Detection
Defense Evasion

Version: 101

Rule authors:

Elastic

Rule license: Elastic License v2

Rule query

edit

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\\SystemApps\\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"]

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/

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