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Detection rules › Sigma

Tamper Windows Defender - ScriptBlockLogging

Severity
high
Author
frack113, elhoim, Tim Shelton (fps, alias support), Swachchhanda Shrawan Poudel, Nasreddine Bencherchali (Nextron Systems)
Source
upstream

Detects PowerShell scripts attempting to disable scheduled scanning and other parts of Windows Defender ATP or set default actions to allow.

MITRE ATT&CK coverage

TacticTechniques
Defense EvasionT1562.001 Impair Defenses: Disable or Modify Tools

Event coverage

ProviderEvent IDTitle
PowerShell4104Creating Scriptblock text (MessageNumber of MessageTotal).

Stages and Predicates

Stage 1: all of selection_options_disabling_preference

ScriptBlockText|contains: Set-MpPreference

Stage 2: all of selection_options_disabling_function

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

Stage 3: all of selection_other_default_actions_allow

ScriptBlockText|contains: Set-MpPreference

Stage 4: all of selection_other_default_actions_func

or:
ScriptBlockText|contains: 'HighThreatDefaultAction Allow'
ScriptBlockText|contains: 'LowThreatDefaultAction Allow'
ScriptBlockText|contains: 'ModerateThreatDefaultAction Allow'
ScriptBlockText|contains: 'SevereThreatDefaultAction Allow'
ScriptBlockText|contains: 'htdefac Allow'
ScriptBlockText|contains: 'ltdefac Allow'
ScriptBlockText|contains: 'mtdefac Allow'
ScriptBlockText|contains: '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
ScriptBlockTextmatch
  • -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

Neighbors

Broader alternatives (more inclusive than this rule)

These rules match a superset of what this rule catches. They cover the same events plus more. Use them if you want wider coverage and can absorb more false positives.