Sticky Key Like Backdoor Execution

Status: test
Severity: critical
Log source: category process_creation, product windows
Author: Florian Roth (Nextron Systems), @twjackomo, Jonhnathan Ribeiro, oscd.community
Source: github.com/SigmaHQ/sigma

Detects the usage and installation of a backdoor that uses an option to register a malicious debugger for built-in tools that are accessible in the login screen

Known false positives

Unlikely

MITRE ATT&CK coverage

Tactic	Techniques
Persistence	`T1546.008` Event Triggered Execution: Accessibility Features
Privilege Escalation	`T1546.008` Event Triggered Execution: Accessibility Features

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: Sticky Key Like Backdoor Execution
id: 2fdefcb3-dbda-401e-ae23-f0db027628bc
related:
    - id: baca5663-583c-45f9-b5dc-ea96a22ce542
      type: derived
status: test
description: Detects the usage and installation of a backdoor that uses an option to register a malicious debugger for built-in tools that are accessible in the login screen
references:
    - https://learn.microsoft.com/en-us/archive/blogs/jonathantrull/detecting-sticky-key-backdoors
author: Florian Roth (Nextron Systems), @twjackomo, Jonhnathan Ribeiro, oscd.community
date: 2018-03-15
modified: 2023-03-07
tags:
    - attack.privilege-escalation
    - attack.persistence
    - attack.t1546.008
    - car.2014-11-003
    - car.2014-11-008
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        ParentImage|endswith: '\winlogon.exe'
        Image|endswith:
            - '\cmd.exe'
            - '\cscript.exe'
            - '\mshta.exe'
            - '\powershell.exe'
            - '\pwsh.exe'
            - '\regsvr32.exe'
            - '\rundll32.exe'
            - '\wscript.exe'
            - '\wt.exe'
        CommandLine|contains:
            - 'sethc.exe'
            - 'utilman.exe'
            - 'osk.exe'
            - 'Magnify.exe'
            - 'Narrator.exe'
            - 'DisplaySwitch.exe'
    condition: selection
falsepositives:
    - Unlikely
level: critical

Stages and Predicates

Stage 0: `condition`

selection

Stage 1: `selection`

selection:
    ParentImage|endswith: '\winlogon.exe'
    Image|endswith:
        - '\cmd.exe'
        - '\cscript.exe'
        - '\mshta.exe'
        - '\powershell.exe'
        - '\pwsh.exe'
        - '\regsvr32.exe'
        - '\rundll32.exe'
        - '\wscript.exe'
        - '\wt.exe'
    CommandLine|contains:
        - 'sethc.exe'
        - 'utilman.exe'
        - 'osk.exe'
        - 'Magnify.exe'
        - 'Narrator.exe'
        - 'DisplaySwitch.exe'

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`CommandLine`	match	`DisplaySwitch.exe` corpus 3 (sigma 3) `Magnify.exe` corpus 3 (sigma 3) `Narrator.exe` corpus 3 (sigma 3) `osk.exe` corpus 3 (sigma 3) `sethc.exe` corpus 4 (sigma 4) `utilman.exe` corpus 3 (sigma 3)	`field:"CommandLine" kind:match`
`Image`	ends_with	`\cmd.exe` corpus 130 (sigma 130) `\cscript.exe` corpus 72 (sigma 72) `\mshta.exe` corpus 66 (sigma 66) `\powershell.exe` corpus 179 (sigma 178, kusto 1) `\pwsh.exe` corpus 165 (sigma 164, kusto 1) `\regsvr32.exe` corpus 64 (sigma 64) `\rundll32.exe` corpus 94 (sigma 94) `\wscript.exe` corpus 74 (sigma 74) `\wt.exe` corpus 5 (sigma 5)	`field:"Image" kind:ends_with`
`ParentImage`	ends_with	`\winlogon.exe` corpus 5 (sigma 5)	`field:"ParentImage" kind:ends_with value:"\winlogon.exe"`