Suspicious .NET Code Compilation

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Suspicious .NET Code Compilation

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Identifies suspicious .NET code execution. connections.

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

Tags:

Elastic
Host
Windows
Threat Detection
Defense Evasion

Version: 5 (version history)

Added (Elastic Stack release): 7.10.0

Last modified (Elastic Stack release): 7.16.0

Rule authors: Elastic

Rule license: Elastic License v2

Rule query

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process where event.type in ("start", "process_started") and
process.name : ("csc.exe", "vbc.exe") and process.parent.name :
("wscript.exe", "mshta.exe", "cscript.exe", "wmic.exe", "svchost.exe",
"rundll32.exe", "cmstp.exe", "regsvr32.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: Obfuscated Files or Information
- ID: T1027
- Reference URL: https://attack.mitre.org/techniques/T1027/

Rule version history

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Version 5 (7.16.0 release)

Formatting only

Version 4 (7.12.0 release)

Formatting only

Version 3 (7.11.2 release)

Formatting only

Version 2 (7.11.0 release)

Updated query, changed from:

event.category:process and event.type:(start or process_started) and
process.name:(csc.exe or vbc.exe) and process.parent.name:(wscript.exe
or mshta.exe or wscript.exe or wmic.exe or svchost.exe or rundll32.exe
or cmstp.exe or regsvr32.exe)

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