Disable Windows Defender AV Security Monitoring

Severity: high
Author: ok @securonix invrep-de, oscd.community, frack113
Source: upstream

Detects attackers attempting to disable Windows Defender using Powershell

MITRE ATT&CK coverage

Tactic	Techniques
Defense Evasion	`T1562.001` Impair Defenses: Disable or Modify Tools

Event coverage

Provider	Event ID	Title
Sysmon	1	Process creation

Stages and Predicates

Stage 1: `all of selection_pwsh_binary`

or:
Image|endswith: '\powershell.exe'
Image|endswith: '\pwsh.exe'
OriginalFileName: PowerShell.EXE
OriginalFileName: pwsh.dll

Stage 2: `all of selection_pwsh_cli`

or:
CommandLine|contains: '-DisableBehaviorMonitoring $true'
CommandLine|contains: '-DisableRuntimeMonitoring $true'

Stage 3: `selection_sc_binary`

or:
Image|endswith: '\sc.exe'
OriginalFileName: sc.exe

Stage 4: `1 of selection_sc_tamper_cmd_stop`

CommandLine|contains: WinDefend
CommandLine|contains: stop

Stage 5: `1 of selection_sc_tamper_cmd_delete`

CommandLine|contains: WinDefend
CommandLine|contains: delete

Stage 6: `1 of selection_sc_tamper_cmd_disabled`

CommandLine|contains: WinDefend
CommandLine|contains: config
CommandLine|contains: 'start=disabled'

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.

Field	Kind	Values
`CommandLine`	match	`-DisableBehaviorMonitoring $true` `-DisableRuntimeMonitoring $true` `WinDefend` corpus 2 (sigma 2) `config` corpus 8 (sigma 8) `delete` corpus 7 (sigma 7) `start=disabled` corpus 2 (sigma 2) `stop`
`Image`	ends_with	`\powershell.exe` corpus 143 (sigma 143) `\pwsh.exe` corpus 140 (sigma 140) `\sc.exe` corpus 17 (sigma 17)
`OriginalFileName`	eq	`PowerShell.EXE` corpus 64 (sigma 60, splunk 4) `pwsh.dll` corpus 72 (sigma 68, splunk 4) `sc.exe` corpus 10 (sigma 10)

Disable Windows Defender AV Security Monitoring

MITRE ATT&CK coverage

Event coverage

Stages and Predicates

Stage 1: all of selection_pwsh_binary

Stage 2: all of selection_pwsh_cli

Stage 3: selection_sc_binary

Stage 4: 1 of selection_sc_tamper_cmd_stop

Stage 5: 1 of selection_sc_tamper_cmd_delete