Network Connection Initiated By Regsvr32.EXE

Hunt Hypothesis

Detects a network connection initiated by “Regsvr32.exe”

Detection Rule

Sigma (Original)

title: Network Connection Initiated By Regsvr32.EXE
id: c7e91a02-d771-4a6d-a700-42587e0b1095
status: test
description: Detects a network connection initiated by "Regsvr32.exe"
references:
    - https://pentestlab.blog/2017/05/11/applocker-bypass-regsvr32/
    - https://oddvar.moe/2017/12/13/applocker-case-study-how-insecure-is-it-really-part-1/
author: Dmitriy Lifanov, oscd.community
date: 2019-10-25
modified: 2023-09-18
tags:
    - attack.execution
    - attack.stealth
    - attack.t1559.001
    - attack.t1218.010
logsource:
    category: network_connection
    product: windows
detection:
    selection:
        Initiated: 'true'
        Image|endswith: '\regsvr32.exe'
    condition: selection
falsepositives:
    - Unknown
level: medium

KQL (Azure Sentinel)

imNetworkSession
| where NetworkDirection =~ "true" and (SrcProcessName endswith "\\regsvr32.exe" or DstProcessName endswith "\\regsvr32.exe")

Required Data Sources

False Positive Guidance

• Unknown

MITRE ATT&CK Context

• Tactic: Execution
• Technique: T1559.001 — T1559.001
• Technique: T1218.010 — T1218.010

References

• https://pentestlab.blog/2017/05/11/applocker-bypass-regsvr32/
• https://oddvar.moe/2017/12/13/applocker-case-study-how-insecure-is-it-really-part-1/
• SigmaHQ Rule