Detection rules › Sigma

Cab File Extraction Via Wusa.EXE From Potentially Suspicious Paths

Status
test
Severity
high
Log source
product windows, category process_creation
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

TacticTechniques
ExecutionNo specific technique

Event coverage

Rule body yaml

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

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
CommandLinematch
  • /extract: corpus 2 (sigma 2)
  • :\PerfLogs\ corpus 11 (sigma 11)
  • :\Users\Public\ corpus 18 (sigma 18)
  • :\Windows\Temp\ corpus 16 (sigma 16)
  • \Appdata\Local\Temp\ corpus 26 (sigma 26)
Imageends_with
  • \wusa.exe corpus 4 (sigma 4)