detection.wiki

Detection rules › Sigma

Potentially Suspicious Child Process Of WinRAR.EXE

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

Detects potentially suspicious child processes of WinRAR.exe.

MITRE ATT&CK coverage

TacticTechniques
ExecutionT1203 Exploitation for Client Execution

Event coverage

ProviderEventTitle
SysmonEvent ID 1Process creation

Rule body yaml

title: Potentially Suspicious Child Process Of WinRAR.EXE
id: 146aace8-9bd6-42ba-be7a-0070d8027b76
related:
    - id: ec3a3c2f-9bb0-4a9b-8f4b-5ec386544343
      type: similar
status: test
description: Detects potentially suspicious child processes of WinRAR.exe.
references:
    - https://www.group-ib.com/blog/cve-2023-38831-winrar-zero-day/
    - https://github.com/knight0x07/WinRAR-Code-Execution-Vulnerability-CVE-2023-38831/blob/26ab6c40b6d2c09bb4fc60feaa4a3a90cfd20c23/Part-1-Overview.md
author: Nasreddine Bencherchali (Nextron Systems)
date: 2023-08-31
tags:
    - attack.execution
    - attack.t1203
logsource:
    category: process_creation
    product: windows
detection:
    selection_parent:
        ParentImage|endswith: '\WinRAR.exe'
    selection_binaries:
        # Note: add additional binaries that the attacker might use
        - Image|endswith:
              - '\cmd.exe'
              - '\cscript.exe'
              - '\mshta.exe'
              - '\powershell.exe'
              - '\pwsh.exe'
              - '\regsvr32.exe'
              - '\rundll32.exe'
              - '\wscript.exe'
        - OriginalFileName:
              - 'Cmd.Exe'
              - 'cscript.exe'
              - 'mshta.exe'
              - 'PowerShell.EXE'
              - 'pwsh.dll'
              - 'regsvr32.exe'
              - 'RUNDLL32.EXE'
              - 'wscript.exe'
    condition: all of selection_*
falsepositives:
    - Unknown
level: medium

Stages and Predicates

Stage 0: condition

all of selection_*

Stage 1: selection_parent

selection_parent:
    ParentImage|endswith: '\WinRAR.exe'

Stage 2: selection_binaries

selection_binaries:
    - Image|endswith:
          - '\cmd.exe'
          - '\cscript.exe'
          - '\mshta.exe'
          - '\powershell.exe'
          - '\pwsh.exe'
          - '\regsvr32.exe'
          - '\rundll32.exe'
          - '\wscript.exe'
    - OriginalFileName:
          - 'Cmd.Exe'
          - 'cscript.exe'
          - 'mshta.exe'
          - 'PowerShell.EXE'
          - 'pwsh.dll'
          - 'regsvr32.exe'
          - 'RUNDLL32.EXE'
          - 'wscript.exe'

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
Imageends_with
  • \cmd.exe corpus 130 (sigma 130)
  • \cscript.exe corpus 73 (sigma 73)
  • \mshta.exe corpus 67 (sigma 67)
  • \powershell.exe corpus 182 (sigma 182)
  • \pwsh.exe corpus 168 (sigma 168)
  • \regsvr32.exe corpus 65 (sigma 65)
  • \rundll32.exe corpus 95 (sigma 95)
  • \wscript.exe corpus 75 (sigma 75)
OriginalFileNameeq
  • Cmd.Exe corpus 65 (sigma 43, splunk 17, elastic 5)
  • PowerShell.EXE corpus 120 (sigma 84, splunk 30, elastic 6)
  • RUNDLL32.EXE corpus 62 (sigma 35, splunk 21, elastic 6)
  • cscript.exe corpus 19 (sigma 17, elastic 2)
  • mshta.exe corpus 22 (sigma 13, splunk 6, elastic 3)
  • pwsh.dll corpus 112 (sigma 79, splunk 30, elastic 3)
  • regsvr32.exe corpus 26 (sigma 17, splunk 6, elastic 3)
  • wscript.exe corpus 20 (sigma 17, elastic 3)
ParentImageends_with
  • \WinRAR.exe corpus 5 (sigma 5)