Detection rules › Sigma

WinRAR Creating Files in Startup Locations

Status
experimental
Severity
high
Log source
product windows, category file_event
Author
Swachchhanda Shrawan Poudel (Nextron Systems)
Source
github.com/SigmaHQ/sigma

Detects WinRAR creating files in Windows startup locations, which may indicate an attempt to establish persistence by adding malicious files to the Startup folder. This kind of behaviour has been associated with exploitation of WinRAR path traversal vulnerability CVE-2025-6218 or CVE-2025-8088.

MITRE ATT&CK coverage

Event coverage

ProviderEventTitle
SysmonEvent ID 11FileCreate

Rule body yaml

title: WinRAR Creating Files in Startup Locations
id: 74a2b37d-fea4-41e0-9ac7-c9fbcf1f60cc
status: experimental
description: |
    Detects WinRAR creating files in Windows startup locations, which may indicate an attempt to establish persistence by adding malicious files to the Startup folder.
    This kind of behaviour has been associated with exploitation of WinRAR path traversal vulnerability CVE-2025-6218 or CVE-2025-8088.
references:
    - https://github.com/mulwareX/CVE-2025-6218-POC
    - https://x.com/0x534c/status/1944694507787710685
    - https://www.welivesecurity.com/en/eset-research/update-winrar-tools-now-romcom-and-others-exploiting-zero-day-vulnerability/
author: Swachchhanda Shrawan Poudel (Nextron Systems)
date: 2025-07-16
tags:
    - attack.privilege-escalation
    - attack.persistence
    - attack.t1547.001
logsource:
    category: file_event
    product: windows
detection:
    selection:
        Image|endswith:
            - '\WinRAR.exe'
            - '\Rar.exe'
        TargetFilename|contains: '\Start Menu\Programs\Startup\'
    condition: selection
falsepositives:
    - Unknown
level: high

Stages and Predicates

Stage 0: condition

selection

Stage 1: selection

selection:
    Image|endswith:
        - '\WinRAR.exe'
        - '\Rar.exe'
    TargetFilename|contains: '\Start Menu\Programs\Startup\'

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
  • \Rar.exe corpus 5 (sigma 5)
  • \WinRAR.exe corpus 6 (sigma 6)
TargetFilenamematch
  • \Start Menu\Programs\Startup\ corpus 5 (sigma 5)