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Detection rules › Sigma

Powershell Keylogging

Status
test
Severity
medium
Log source
product windows, category ps_script
Author
frack113
Source
github.com/SigmaHQ/sigma

Adversaries may log user keystrokes to intercept credentials as the user types them.

MITRE ATT&CK coverage

TacticTechniques
Credential AccessT1056.001 Input Capture: Keylogging
CollectionT1056.001 Input Capture: Keylogging

Event coverage

ProviderEventTitle
PowerShellEvent ID 4104Creating Scriptblock text (MessageNumber of MessageTotal).

Rule body yaml

title: Powershell Keylogging
id: 34f90d3c-c297-49e9-b26d-911b05a4866c
status: test
description: Adversaries may log user keystrokes to intercept credentials as the user types them.
references:
    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1218/T1218.md
    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1056.001/src/Get-Keystrokes.ps1
author: frack113
date: 2021-07-30
modified: 2022-07-11
tags:
    - attack.credential-access
    - attack.collection
    - attack.t1056.001
logsource:
    product: windows
    category: ps_script
    definition: 'Requirements: Script Block Logging must be enabled'
detection:
    selection_basic:
        ScriptBlockText|contains: 'Get-Keystrokes'
    selection_high: # want to run in background and keyboard
        ScriptBlockText|contains|all:
            - 'Get-ProcAddress user32.dll GetAsyncKeyState'
            - 'Get-ProcAddress user32.dll GetForegroundWindow'
    condition: 1 of selection_*
falsepositives:
    - Unknown
level: medium

Stages and Predicates

Stage 0: condition

1 of selection_*

Stage 1: selection_basic

selection_basic:
    ScriptBlockText|contains: 'Get-Keystrokes'

Stage 2: selection_high

selection_high:
    ScriptBlockText|contains|all:
        - 'Get-ProcAddress user32.dll GetAsyncKeyState'
        - 'Get-ProcAddress user32.dll GetForegroundWindow'

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
ScriptBlockTextmatch
  • Get-Keystrokes corpus 2 (sigma 2)
  • Get-ProcAddress user32.dll GetAsyncKeyState
  • Get-ProcAddress user32.dll GetForegroundWindow