Potential Exploitation Attempt From Office Application

Status: test
Severity: high
Log source: category process_creation, product windows
Author: Christian Burkard (Nextron Systems), @SBousseaden (idea)
Source: github.com/SigmaHQ/sigma

Detects Office applications executing a child process that includes directory traversal patterns. This could be an attempt to exploit CVE-2022-30190 (MSDT RCE) or CVE-2021-40444 (MSHTML RCE)

MITRE ATT&CK coverage

Tactic	Techniques
Execution	No specific technique
Stealth	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: Potential Exploitation Attempt From Office Application
id: 868955d9-697e-45d4-a3da-360cefd7c216
status: test
description: Detects Office applications executing a child process that includes directory traversal patterns. This could be an attempt to exploit CVE-2022-30190 (MSDT RCE) or CVE-2021-40444 (MSHTML RCE)
references:
    - https://twitter.com/sbousseaden/status/1531653369546301440
    - https://msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2021-40444
    - https://msrc.microsoft.com/update-guide/vulnerability/CVE-2022-30190
author: Christian Burkard (Nextron Systems), @SBousseaden (idea)
date: 2022-06-02
modified: 2023-02-04
tags:
    - attack.execution
    - cve.2021-40444
    - detection.emerging-threats
    - attack.stealth
logsource:
    product: windows
    category: process_creation
detection:
    selection:
        ParentImage|endswith:
            - '\winword.exe'
            - '\excel.exe'
            - '\powerpnt.exe'
            - '\msaccess.exe'
            - '\mspub.exe'
            - '\eqnedt32.exe'
            - '\visio.exe'
        CommandLine|contains:
            - '../../../..'
            - '..\..\..\..'
            - '..//..//..//..'
    condition: selection
falsepositives:
    - Unknown
level: high

Stages and Predicates

Stage 0: `condition`

selection

Stage 1: `selection`

selection:
    ParentImage|endswith:
        - '\winword.exe'
        - '\excel.exe'
        - '\powerpnt.exe'
        - '\msaccess.exe'
        - '\mspub.exe'
        - '\eqnedt32.exe'
        - '\visio.exe'
    CommandLine|contains:
        - '../../../..'
        - '..\..\..\..'
        - '..//..//..//..'

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`CommandLine`	match	`../../../..` `..//..//..//..` `..\..\..\..`	`field:"CommandLine" kind:match`
`ParentImage`	ends_with	`\eqnedt32.exe` corpus 5 (sigma 5) `\excel.exe` corpus 8 (sigma 8) `\msaccess.exe` corpus 4 (sigma 4) `\mspub.exe` corpus 4 (sigma 4) `\powerpnt.exe` corpus 6 (sigma 6) `\visio.exe` corpus 4 (sigma 4) `\winword.exe` corpus 10 (sigma 10)	`field:"ParentImage" kind:ends_with`