Cab File Extraction Via Wusa.EXE From Potentially Suspicious Paths

Status: test
Severity: high
Log source: category process_creation, product windows
Author: Nasreddine Bencherchali (Nextron Systems)
Source: github.com/SigmaHQ/sigma

Detects the execution of the "wusa.exe" (Windows Update Standalone Installer) utility to extract ".cab" files using the "/extract" argument from potentially suspicious paths.

MITRE ATT&CK coverage

Tactic	Techniques
Execution	No specific technique

Telemetry coverage

Provider	Record / event type
Sysmon	Event ID 1: Process creation
Security-Auditing	Event ID 4688: A new process has been created.

Rule body

title: Cab File Extraction Via Wusa.EXE From Potentially Suspicious Paths
id: c74c0390-3e20-41fd-a69a-128f0275a5ea
related:
    - id: 59b39960-5f9d-4a49-9cef-1e4d2c1d0cb9
      type: derived
status: test
description: |
    Detects the execution of the "wusa.exe" (Windows Update Standalone Installer) utility to extract ".cab" files using the "/extract" argument from potentially suspicious paths.
references:
    - https://web.archive.org/web/20180331144337/https://www.fireeye.com/blog/threat-research/2018/03/sanny-malware-delivery-method-updated-in-recently-observed-attacks.html
    - https://www.echotrail.io/insights/search/wusa.exe/
author: Nasreddine Bencherchali (Nextron Systems)
date: 2022-08-05
modified: 2023-11-28
tags:
    - attack.execution
logsource:
    category: process_creation
    product: windows
detection:
    selection_root:
        Image|endswith: '\wusa.exe'
        CommandLine|contains: '/extract:'
    selection_paths:
        CommandLine|contains:
            - ':\PerfLogs\'
            - ':\Users\Public\'
            - ':\Windows\Temp\'
            - '\Appdata\Local\Temp\'
            # - '\Desktop\'
            # - '\Downloads\'
    condition: all of selection_*
falsepositives:
    - Unknown
level: high

Stages and Predicates

Stage 0: `condition`

all of selection_*

Stage 1: `selection_root`

selection_root:
    Image|endswith: '\wusa.exe'
    CommandLine|contains: '/extract:'

Stage 2: `selection_paths`

selection_paths:
    CommandLine|contains:
        - ':\PerfLogs\'
        - ':\Users\Public\'
        - ':\Windows\Temp\'
        - '\Appdata\Local\Temp\'

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`CommandLine`	match	`/extract:` corpus 2 (sigma 2) `:\PerfLogs\` corpus 11 (sigma 11) `:\Users\Public\` corpus 20 (sigma 18, elastic 2) `:\Windows\Temp\` corpus 16 (sigma 16) `\Appdata\Local\Temp\` corpus 28 (sigma 26, elastic 2)	`field:"CommandLine" kind:match`
`Image`	ends_with	`\wusa.exe` corpus 4 (sigma 4)	`field:"Image" kind:ends_with value:"\wusa.exe"`