Suspicious Extrac32 Execution

Status: test
Severity: medium
Log source: category process_creation, product windows
Author: frack113
Source: github.com/SigmaHQ/sigma

Download or Copy file with Extrac32

MITRE ATT&CK coverage

Tactic	Techniques
Command & Control	`T1105` Ingress Tool Transfer

Telemetry coverage

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

Rule body

title: Suspicious Extrac32 Execution
id: aa8e035d-7be4-48d3-a944-102aec04400d
status: test
description: Download or Copy file with Extrac32
references:
    - https://lolbas-project.github.io/lolbas/Binaries/Extrac32/
author: frack113
date: 2021-11-26
modified: 2022-08-13
tags:
    - attack.command-and-control
    - attack.t1105
logsource:
    category: process_creation
    product: windows
detection:
    selection_lolbas:
        - CommandLine|contains: extrac32.exe
        - Image|endswith: '\extrac32.exe'
        - OriginalFileName: 'extrac32.exe'
    selection_archive:
        CommandLine|contains: '.cab'
    selection_options:
        CommandLine|contains:
            - /C
            - /Y
            - ' \\\\'
    condition: all of selection_*
falsepositives:
    - Unknown
level: medium

Stages and Predicates

Stage 0: `condition`

all of selection_*

Stage 1: `selection_lolbas`

selection_lolbas:
    - CommandLine|contains: extrac32.exe
    - Image|endswith: '\extrac32.exe'
    - OriginalFileName: 'extrac32.exe'

Stage 2: `selection_archive`

selection_archive:
    CommandLine|contains: '.cab'

Stage 3: `selection_options`

selection_options:
    CommandLine|contains:
        - /C
        - /Y
        - ' \\\\'

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`CommandLine`	match	`\\\\` corpus 8 (sigma 8) `.cab` corpus 5 (sigma 5) `/C` corpus 15 (sigma 13, splunk 2) `/Y` `extrac32.exe` corpus 2 (sigma 2)	`field:"CommandLine" kind:match`
`Image`	ends_with	`\extrac32.exe` corpus 2 (sigma 2)	`field:"Image" kind:ends_with value:"\extrac32.exe"`
`OriginalFileName`	eq	`extrac32.exe` corpus 2 (sigma 1, elastic 1)	`field:"OriginalFileName" kind:eq value:"extrac32.exe"`

Suspicious Extrac32 Execution

MITRE ATT&CK coverage

Telemetry coverage

Rule body

Stages and Predicates

Stage 0: condition

Stage 1: selection_lolbas

Stage 2: selection_archive

Stage 3: selection_options

Indicators

Stage 0: `condition`

Stage 1: `selection_lolbas`

Stage 2: `selection_archive`

Stage 3: `selection_options`