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Detection rules › Sigma

Sticky Key Like Backdoor Execution

Status
test
Severity
critical
Log source
product windows, category process_creation
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

MITRE ATT&CK coverage

TacticTechniques
PersistenceT1546.008 Event Triggered Execution: Accessibility Features
Privilege EscalationT1546.008 Event Triggered Execution: Accessibility Features

Event coverage

ProviderEventTitle
SysmonEvent ID 1Process creation
Security-AuditingEvent ID 4688A new process has been created.

Rule body yaml

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

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
  • 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)
Imageends_with
  • \cmd.exe corpus 130 (sigma 130)
  • \cscript.exe corpus 73 (sigma 73)
  • \mshta.exe corpus 67 (sigma 67)
  • \powershell.exe corpus 182 (sigma 182)
  • \pwsh.exe corpus 168 (sigma 168)
  • \regsvr32.exe corpus 65 (sigma 65)
  • \rundll32.exe corpus 95 (sigma 95)
  • \wscript.exe corpus 75 (sigma 75)
  • \wt.exe corpus 5 (sigma 5)
ParentImageends_with
  • \winlogon.exe corpus 5 (sigma 5)