Compressed File Extraction Via Tar.EXE

Status: test
Severity: low
Log source: category process_creation, product windows
Author: AdmU3
Source: github.com/SigmaHQ/sigma

Detects execution of "tar.exe" in order to extract compressed file. Adversaries may abuse various utilities in order to decompress data to avoid detection.

Known false positives

Likely

MITRE ATT&CK coverage

Tactic	Techniques
Collection	`T1560.001` Archive Collected Data: Archive via Utility

Telemetry coverage

Provider	Record / event type
Sysmon	Event ID 1: Process creation

Rule body

title: Compressed File Extraction Via Tar.EXE
id: bf361876-6620-407a-812f-bfe11e51e924
status: test
description: |
    Detects execution of "tar.exe" in order to extract compressed file.
    Adversaries may abuse various utilities in order to decompress data to avoid detection.
references:
    - https://unit42.paloaltonetworks.com/chromeloader-malware/
    - https://lolbas-project.github.io/lolbas/Binaries/Tar/
    - https://symantec-enterprise-blogs.security.com/blogs/threat-intelligence/cicada-apt10-japan-espionage
author: AdmU3
date: 2023-12-19
tags:
    - attack.collection
    - attack.exfiltration
    - attack.t1560
    - attack.t1560.001
logsource:
    product: windows
    category: process_creation
detection:
    selection_img:
        - Image|endswith: '\tar.exe'
        - OriginalFileName: 'bsdtar'
    selection_extract:
        CommandLine|contains: '-x'
    condition: all of selection_*
falsepositives:
    - Likely
level: low

Stages and Predicates

Stage 0: `condition`

all of selection_*

Stage 1: `selection_img`

selection_img:
    - Image|endswith: '\tar.exe'
    - OriginalFileName: 'bsdtar'

Stage 2: `selection_extract`

selection_extract:
    CommandLine|contains: '-x'

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`CommandLine`	match	`-x` corpus 2 (sigma 2)	`field:"CommandLine" kind:match value:"-x"`
`Image`	ends_with	`\tar.exe` corpus 2 (sigma 2)	`field:"Image" kind:ends_with value:"\tar.exe"`
`OriginalFileName`	eq	`bsdtar` corpus 4 (sigma 2, elastic 2)	`field:"OriginalFileName" kind:eq value:"bsdtar"`