Suspicious WinRAR Child Process Execution Attempt on Windows (CVE-2023-38331)

Alerts on WinRAR spawning command/scripting child processes tied to Temp\Rar$ activity consistent with CVE-2023-38331 exploitation attempts.

FreeReviewedSigma · High · v5

Product: windows
Category: process_creation
Author: Nasreddine Bencherchali (Nextron Systems), Andreas Braathen (mnemonic.io) (SigmaHQ), DRL 1.1
Published: 2023-08-30
Updated: 2026-07-31

Analysis Detection

ATT&CK techniques

Execution

Recon
Resource Dev
Initial Access
Execution
- T1203Exploitation for Client Execution
Persistence
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule flags Windows process creation events where WinRAR (WinRAR.exe) is launching a child process with command-line patterns consistent with exploitation behavior. It looks for activity that includes execution from WinRAR’s temporary Rar$ extraction path and a suspicious double extension in the command line. Additional matches check for common command/script interpreters (cmd.exe, cscript.exe, powershell/pwsh, wscript) based on the child process image and original filename indicators.

Reporting behind it

Related detections9 linkedT1203 — drag to rearrange

Malicious Script Execution from WinRAR Extraction Directory via CVE-2023-38831

Suspicious Execution From WinRAR Temporary Extraction Path via Command Line (via process_creation)

Malicious Shell Execution via Foomatic-rip Print Filter through CUPS Exploit

Suspicious Network Connection From CUPS Foomatic-Rip Child Process

Antivirus signatures matching APT malware naming patterns

Antivirus Remote Access Tool Signature Matches Known RAT Names

Malicious Microsoft Word Spawning Anomalous Child Process via CVE-2023-36884 (via process_creation)

Possible ExifTool CVE-2026-3102 Command Injection via Child Process Spawn (via process_creation)

Malicious Equation Editor Child Process Execution via process_creation

Suspicious WinRAR Child Process Execution Attempt on Windows (CVE-2023-38331)

Pivot detection · T1203 · 9 related

Changelog

v5
Candidate ingested via manual entry.2026-07-31
v4
Candidate ingested via manual entry.2026-07-31
v3
Candidate ingested via manual entry.2026-07-31
v2
Candidate ingested via manual entry.2026-07-31
v1
No changelog recorded for this version.2026-07-30

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.

suspicious-winrar-child-process-execution-attempt-cve-2023-38331-on-windows-ec3a3c2f

title: Suspicious WinRAR Child Process Execution Attempt on Windows (CVE-2023-38331)
id: 878ecab2-ad01-44b8-9eab-135b1d7c1232
related:
  - id: e4556676-fc5c-4e95-8c39-5ef27791541f
    type: similar
  - id: ec3a3c2f-9bb0-4a9b-8f4b-5ec386544343
    type: derived
status: test
description: This rule flags Windows process creation events where WinRAR (WinRAR.exe) is launching a child process with command-line patterns consistent with exploitation behavior. It looks for activity that includes execution from WinRAR’s temporary Rar$ extraction path and a suspicious double extension in the command line. Additional matches check for common command/script interpreters (cmd.exe, cscript.exe, powershell/pwsh, wscript) based on the child process image and original filename indicators.
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
  - https://github.com/SigmaHQ/sigma/blob/master/rules-emerging-threats/2023/Exploits/CVE-2023-38831/proc_creation_win_exploit_cve_2023_38831_winrar_child_proc.yml
author: Nasreddine Bencherchali (Nextron Systems), Andreas Braathen (mnemonic.io), Huntrule Team
date: 2023-08-30
modified: 2024-01-22
tags:
  - detection.emerging-threats
  - attack.execution
  - attack.t1203
  - cve.2023-38331
logsource:
  category: process_creation
  product: windows
detection:
  selection_parent:
    ParentImage|endswith: \WinRAR.exe
  selection_folder:
    CommandLine|contains: \AppData\Local\Temp\Rar$
  selection_double_ext:
    CommandLine|re: \.[a-zA-Z0-9]{1,4} \.
  selection_binaries:
    - Image|endswith:
        - \cmd.exe
        - \cscript.exe
        - \powershell.exe
        - \pwsh.exe
        - \wscript.exe
    - OriginalFileName:
        - Cmd.Exe
        - cscript.exe
        - PowerShell.EXE
        - pwsh.dll
        - wscript.exe
  condition: all of selection_*
falsepositives:
  - Unlikely
level: high
license: DRL-1.1

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