PUA - Wsudo Suspicious Execution

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

Detects usage of wsudo (Windows Sudo Utility). Which is a tool that let the user execute programs with different permissions (System, Trusted Installer, Administrator...etc)

MITRE ATT&CK coverage

Tactic	Techniques
Execution	`T1059` Command and Scripting Interpreter

Telemetry coverage

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

Rule body

title: PUA - Wsudo Suspicious Execution
id: bdeeabc9-ff2a-4a51-be59-bb253aac7891
status: test
description: Detects usage of wsudo (Windows Sudo Utility). Which is a tool that let the user execute programs with different permissions (System, Trusted Installer, Administrator...etc)
references:
    - https://github.com/M2Team/Privexec/
author: Nasreddine Bencherchali (Nextron Systems)
date: 2022-12-02
modified: 2023-02-14
tags:
    - attack.execution
    - attack.privilege-escalation
    - attack.t1059
logsource:
    category: process_creation
    product: windows
detection:
    selection_metadata:
        - Image|endswith: '\wsudo.exe'
        - OriginalFileName: 'wsudo.exe'
        - Description: 'Windows sudo utility'
        - ParentImage|endswith: '\wsudo-bridge.exe'
    selection_cli:
        CommandLine|contains:
            - '-u System'
            - '-uSystem'
            - '-u TrustedInstaller'
            - '-uTrustedInstaller'
            - ' --ti '
    condition: 1 of selection_*
falsepositives:
    - Unknown
level: high

Stages and Predicates

Stage 0: `condition`

1 of selection_*

Stage 1: `selection_metadata`

selection_metadata:
    - Image|endswith: '\wsudo.exe'
    - OriginalFileName: 'wsudo.exe'
    - Description: 'Windows sudo utility'
    - ParentImage|endswith: '\wsudo-bridge.exe'

Stage 2: `selection_cli`

selection_cli:
    CommandLine|contains:
        - '-u System'
        - '-uSystem'
        - '-u TrustedInstaller'
        - '-uTrustedInstaller'
        - ' --ti '

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`CommandLine`	match	`--ti` `-u System` `-u TrustedInstaller` `-uSystem` `-uTrustedInstaller`	`field:"CommandLine" kind:match`
`Description`	eq	`Windows sudo utility`	`field:"Description" kind:eq value:"Windows sudo utility"`
`Image`	ends_with	`\wsudo.exe`	`field:"Image" kind:ends_with value:"\wsudo.exe"`
`OriginalFileName`	eq	`wsudo.exe`	`field:"OriginalFileName" kind:eq value:"wsudo.exe"`
`ParentImage`	ends_with	`\wsudo-bridge.exe`	`field:"ParentImage" kind:ends_with value:"\wsudo-bridge.exe"`