detection.wiki

Detection rules › Sigma

Regsvr32 Execution From Potential Suspicious Location

Status
test
Severity
medium
Log source
product windows, category process_creation
Author
Florian Roth (Nextron Systems), Nasreddine Bencherchali (Nextron Systems)
Source
github.com/SigmaHQ/sigma

Detects execution of regsvr32 where the DLL is located in a potentially suspicious location.

MITRE ATT&CK coverage

TacticTechniques
StealthT1218.010 System Binary Proxy Execution: Regsvr32

Event coverage

ProviderEventTitle
SysmonEvent ID 1Process creation

Rule body yaml

title: Regsvr32 Execution From Potential Suspicious Location
id: 9525dc73-0327-438c-8c04-13c0e037e9da
related:
    - id: 8e2b24c9-4add-46a0-b4bb-0057b4e6187d
      type: obsolete
status: test
description: Detects execution of regsvr32 where the DLL is located in a potentially suspicious location.
references:
    - https://web.archive.org/web/20171001085340/https://subt0x10.blogspot.com/2017/04/bypass-application-whitelisting-script.html
    - https://app.any.run/tasks/34221348-072d-4b70-93f3-aa71f6ebecad/
author: Florian Roth (Nextron Systems), Nasreddine Bencherchali (Nextron Systems)
date: 2023-05-26
tags:
    - attack.stealth
    - attack.t1218.010
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - Image|endswith: '\regsvr32.exe'
        - OriginalFileName: 'REGSVR32.EXE'
    selection_cli:
        CommandLine|contains:
            - ':\ProgramData\'
            - ':\Temp\'
            - ':\Users\Public\'
            - ':\Windows\Temp\'
            - '\AppData\Local\Temp\'
            - '\AppData\Roaming\'
    condition: all of selection_*
falsepositives:
    - Some installers might execute "regsvr32" with DLLs located in %TEMP% or in %PROGRAMDATA%. Apply additional filters if necessary.
level: medium

Stages and Predicates

Stage 0: condition

all of selection_*

Stage 1: selection_img

selection_img:
    - Image|endswith: '\regsvr32.exe'
    - OriginalFileName: 'REGSVR32.EXE'

Stage 2: selection_cli

selection_cli:
    CommandLine|contains:
        - ':\ProgramData\'
        - ':\Temp\'
        - ':\Users\Public\'
        - ':\Windows\Temp\'
        - '\AppData\Local\Temp\'
        - '\AppData\Roaming\'

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

FieldKindValues
CommandLinematch
  • :\ProgramData\ corpus 9 (sigma 9)
  • :\Temp\ corpus 14 (sigma 14)
  • :\Users\Public\ corpus 18 (sigma 18)
  • :\Windows\Temp\ corpus 16 (sigma 16)
  • \AppData\Local\Temp\ corpus 26 (sigma 26)
  • \AppData\Roaming\ corpus 16 (sigma 16)
Imageends_with
  • \regsvr32.exe corpus 65 (sigma 65)
OriginalFileNameeq
  • REGSVR32.EXE corpus 26 (sigma 17, splunk 6, elastic 3)