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Detection rules › Sigma

Tamper Windows Defender - PSClassic

Status
test
Severity
high
Log source
product windows, category ps_classic_provider_start
Author
frack113, Nasreddine Bencherchali (Nextron Systems)
Source
github.com/SigmaHQ/sigma

Attempting to disable scheduled scanning and other parts of Windows Defender ATP or set default actions to allow.

MITRE ATT&CK coverage

TacticTechniques
Defense ImpairmentT1685 Disable or Modify Tools

Event coverage

ProviderEvent
PowerShellEvent ID 600

Rule body yaml

title: Tamper Windows Defender - PSClassic
id: ec19ebab-72dc-40e1-9728-4c0b805d722c
related:
    - id: 14c71865-6cd3-44ae-adaa-1db923fae5f2
      type: similar
status: test
description: Attempting to disable scheduled scanning and other parts of Windows Defender ATP or set default actions to allow.
references:
    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1562.001/T1562.001.md
author: frack113, Nasreddine Bencherchali (Nextron Systems)
date: 2021-06-07
modified: 2024-01-02
tags:
    - attack.defense-impairment
    - attack.t1685
logsource:
    product: windows
    category: ps_classic_provider_start
detection:
    selection_set_mppreference:
        Data|contains: 'Set-MpPreference'
    selection_options_bool_allow:
        Data|contains:
            - '-dbaf $true'
            - '-dbaf 1'
            - '-dbm $true'
            - '-dbm 1'
            - '-dips $true'
            - '-dips 1'
            - '-DisableArchiveScanning $true'
            - '-DisableArchiveScanning 1'
            - '-DisableBehaviorMonitoring $true'
            - '-DisableBehaviorMonitoring 1'
            - '-DisableBlockAtFirstSeen $true'
            - '-DisableBlockAtFirstSeen 1'
            - '-DisableCatchupFullScan $true'
            - '-DisableCatchupFullScan 1'
            - '-DisableCatchupQuickScan $true'
            - '-DisableCatchupQuickScan 1'
            - '-DisableIntrusionPreventionSystem $true'
            - '-DisableIntrusionPreventionSystem 1'
            - '-DisableIOAVProtection $true'
            - '-DisableIOAVProtection 1'
            - '-DisableRealtimeMonitoring $true'
            - '-DisableRealtimeMonitoring 1'
            - '-DisableRemovableDriveScanning $true'
            - '-DisableRemovableDriveScanning 1'
            - '-DisableScanningMappedNetworkDrivesForFullScan $true'
            - '-DisableScanningMappedNetworkDrivesForFullScan 1'
            - '-DisableScanningNetworkFiles $true'
            - '-DisableScanningNetworkFiles 1'
            - '-DisableScriptScanning $true'
            - '-DisableScriptScanning 1'
            - '-MAPSReporting $false'
            - '-MAPSReporting 0'
            - '-drdsc $true'
            - '-drdsc 1'
            - '-drtm $true'
            - '-drtm 1'
            - '-dscrptsc $true'
            - '-dscrptsc 1'
            - '-dsmndf $true'
            - '-dsmndf 1'
            - '-dsnf $true'
            - '-dsnf 1'
            - '-dss $true'
            - '-dss 1'
    selection_options_actions_func:
        Data|contains:
            - 'HighThreatDefaultAction Allow'
            - 'htdefac Allow'
            - 'LowThreatDefaultAction Allow'
            - 'ltdefac Allow'
            - 'ModerateThreatDefaultAction Allow'
            - 'mtdefac Allow'
            - 'SevereThreatDefaultAction Allow'
            - 'stdefac Allow'
    condition: selection_set_mppreference and 1 of selection_options_*
falsepositives:
    - Legitimate PowerShell scripts that disable Windows Defender for troubleshooting purposes. Must be investigated.
level: high

Stages and Predicates

Stage 0: condition

selection_set_mppreference and 1 of selection_options_*

Stage 1: selection_set_mppreference

selection_set_mppreference:
    Data|contains: 'Set-MpPreference'

Stage 2: selection_options_bool_allow

selection_options_bool_allow:
    Data|contains:
        - '-dbaf $true'
        - '-dbaf 1'
        - '-dbm $true'
        - '-dbm 1'
        - '-dips $true'
        - '-dips 1'
        - '-DisableArchiveScanning $true'
        - '-DisableArchiveScanning 1'
        - '-DisableBehaviorMonitoring $true'
        - '-DisableBehaviorMonitoring 1'
        - '-DisableBlockAtFirstSeen $true'
        - '-DisableBlockAtFirstSeen 1'
        - '-DisableCatchupFullScan $true'
        - '-DisableCatchupFullScan 1'
        - '-DisableCatchupQuickScan $true'
        - '-DisableCatchupQuickScan 1'
        - '-DisableIntrusionPreventionSystem $true'
        - '-DisableIntrusionPreventionSystem 1'
        - '-DisableIOAVProtection $true'
        - '-DisableIOAVProtection 1'
        - '-DisableRealtimeMonitoring $true'
        - '-DisableRealtimeMonitoring 1'
        - '-DisableRemovableDriveScanning $true'
        - '-DisableRemovableDriveScanning 1'
        - '-DisableScanningMappedNetworkDrivesForFullScan $true'
        - '-DisableScanningMappedNetworkDrivesForFullScan 1'
        - '-DisableScanningNetworkFiles $true'
        - '-DisableScanningNetworkFiles 1'
        - '-DisableScriptScanning $true'
        - '-DisableScriptScanning 1'
        - '-MAPSReporting $false'
        - '-MAPSReporting 0'
        - '-drdsc $true'
        - '-drdsc 1'
        - '-drtm $true'
        - '-drtm 1'
        - '-dscrptsc $true'
        - '-dscrptsc 1'
        - '-dsmndf $true'
        - '-dsmndf 1'
        - '-dsnf $true'
        - '-dsnf 1'
        - '-dss $true'
        - '-dss 1'

Stage 3: selection_options_actions_func

selection_options_actions_func:
    Data|contains:
        - 'HighThreatDefaultAction Allow'
        - 'htdefac Allow'
        - 'LowThreatDefaultAction Allow'
        - 'ltdefac Allow'
        - 'ModerateThreatDefaultAction Allow'
        - 'mtdefac Allow'
        - 'SevereThreatDefaultAction Allow'
        - 'stdefac Allow'

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
Datamatch
  • -DisableArchiveScanning $true
  • -DisableArchiveScanning 1
  • -DisableBehaviorMonitoring $true
  • -DisableBehaviorMonitoring 1
  • -DisableBlockAtFirstSeen $true
  • -DisableBlockAtFirstSeen 1
  • -DisableCatchupFullScan $true
  • -DisableCatchupFullScan 1
  • -DisableCatchupQuickScan $true
  • -DisableCatchupQuickScan 1
  • -DisableIOAVProtection $true
  • -DisableIOAVProtection 1
  • -DisableIntrusionPreventionSystem $true
  • -DisableIntrusionPreventionSystem 1
  • -DisableRealtimeMonitoring $true
  • -DisableRealtimeMonitoring 1
  • -DisableRemovableDriveScanning $true
  • -DisableRemovableDriveScanning 1
  • -DisableScanningMappedNetworkDrivesForFullScan $true
  • -DisableScanningMappedNetworkDrivesForFullScan 1
  • -DisableScanningNetworkFiles $true
  • -DisableScanningNetworkFiles 1
  • -DisableScriptScanning $true
  • -DisableScriptScanning 1
  • -MAPSReporting $false
  • -MAPSReporting 0
  • -dbaf $true
  • -dbaf 1
  • -dbm $true
  • -dbm 1
  • -dips $true
  • -dips 1
  • -drdsc $true
  • -drdsc 1
  • -drtm $true
  • -drtm 1
  • -dscrptsc $true
  • -dscrptsc 1
  • -dsmndf $true
  • -dsmndf 1
  • -dsnf $true
  • -dsnf 1
  • -dss $true
  • -dss 1
  • HighThreatDefaultAction Allow
  • LowThreatDefaultAction Allow
  • ModerateThreatDefaultAction Allow
  • Set-MpPreference
  • SevereThreatDefaultAction Allow
  • htdefac Allow
  • ltdefac Allow
  • mtdefac Allow
  • stdefac Allow