Windows Rar.exe Files Added to Archive Activity

Alerts when Windows rar.exe is used to add files to an archive using the " a " command-line pattern.

FreeUnreviewedSigmalowv1

windows-rar-exe-files-added-to-archive-activity-6f3e2987

title: Windows Rar.exe Files Added to Archive Activity
id: 4df6d82c-5055-43e9-a32a-07485c207e0e
status: test
description: This rule flags process executions of rar.exe where the command line contains the archive-file add syntax (" a "). Attackers commonly compress collected files into archives to reduce size, improve portability, and facilitate staging or exfiltration. The detection relies on Windows process creation telemetry including the executed image path/name and command-line contents.
references:
  - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1560.001/T1560.001.md
  - https://eqllib.readthedocs.io/en/latest/analytics/1ec33c93-3d0b-4a28-8014-dbdaae5c60ae.html
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/process_creation/proc_creation_win_rar_compress_data.yml
author: Timur Zinniatullin, E.M. Anhaus, oscd.community, Huntrule Team
date: 2019-10-21
modified: 2023-02-05
tags:
  - attack.collection
  - attack.t1560.001
logsource:
  category: process_creation
  product: windows
detection:
  selection:
    Image|endswith: \rar.exe
    CommandLine|contains: " a "
  condition: selection
falsepositives:
  - Highly likely if rar is a default archiver in the monitored environment.
level: low
license: DRL-1.1
related:
  - id: 6f3e2987-db24-4c78-a860-b4f4095a7095
    type: derived

What it detects

This rule flags process executions of rar.exe where the command line contains the archive-file add syntax (" a "). Attackers commonly compress collected files into archives to reduce size, improve portability, and facilitate staging or exfiltration. The detection relies on Windows process creation telemetry including the executed image path/name and command-line contents.

Known false positives

Highly likely if rar is a default archiver in the monitored environment.

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