Cab File Extraction Via Wusa.EXE From Potentially Suspicious Paths

Severity: high
Author: Nasreddine Bencherchali (Nextron Systems)
Source: upstream

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

Event coverage

Provider	Event ID	Title
Sysmon	1	Process creation
Security-Auditing	4688	A new process has been created.

Stages and Predicates

Stage 1: `all of selection_root`

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

Stage 2: `all of selection_paths`

or:
CommandLine|contains: ':\PerfLogs\'
CommandLine|contains: ':\Users\Public\'
CommandLine|contains: ':\Windows\Temp\'
CommandLine|contains: '\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.

Field	Kind	Values
`CommandLine`	match	`/extract:` `:\PerfLogs\` corpus 6 (sigma 6) `:\Users\Public\` corpus 14 (sigma 14) `:\Windows\Temp\` corpus 15 (sigma 15) `\Appdata\Local\Temp\` corpus 2 (sigma 2)
`Image`	ends_with	`\wusa.exe` corpus 3 (sigma 3)

Neighbors

Broader alternatives (more inclusive than this rule)

These rules match a superset of what this rule catches. They cover the same events plus more. Use them if you want wider coverage and can absorb more false positives.

Wusa.EXE Executed By Parent Process Located In Suspicious Location [sigma] (drops 1 filter this rule applies) (first-stage match only; downstream stages may differ)