Tamper Windows Defender - PSClassic — Sigma Rule

Rule metadata and linked tags

Author: frack113, Nasreddine Bencherchali (Nextron Systems). Source status: test; severity: high. Source dates: 2021-06-07 / 2024-01-02.

{
  "product": "windows",
  "category": "ps_classic_provider_start"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: cf87fbf0e4c3a33baa3ed28ad213a8ab49ea205cfa8a099378754697d386b434

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

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

Original YAML and metadata in JSON

False positives

• Legitimate PowerShell scripts that disable Windows Defender for troubleshooting purposes. Must be investigated.

Source references

• https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1562.001/T1562.001.md