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Detection rules › Sigma

Microsoft Defender Blocked from Loading Unsigned DLL

Status
test
Severity
high
Log source
product windows, service security-mitigations
Author
Bhabesh Raj
Source
github.com/SigmaHQ/sigma

Detects Code Integrity (CI) engine blocking Microsoft Defender's processes (MpCmdRun and NisSrv) from loading unsigned DLLs which may be an attempt to sideload arbitrary DLL

MITRE ATT&CK coverage

TacticTechniques
ExecutionT1574.001 Hijack Execution Flow: DLL
StealthT1574.001 Hijack Execution Flow: DLL

Event coverage

ProviderEventTitle
Security-MitigationsEvent ID 11Process 'ProcessPath' (PID ProcessId) would have been blocked from loading the non-Microsoft-signed binary 'ImageName'.
Security-MitigationsEvent ID 12Process 'ProcessPath' (PID ProcessId) was blocked from loading the non-Microsoft-signed binary 'ImageName'.

Rule body yaml

title: Microsoft Defender Blocked from Loading Unsigned DLL
id: 0b0ea3cc-99c8-4730-9c53-45deee2a4c86
status: test
description: Detects Code Integrity (CI) engine blocking Microsoft Defender's processes (MpCmdRun and NisSrv) from loading unsigned DLLs which may be an attempt to sideload arbitrary DLL
references:
    - https://www.sentinelone.com/blog/living-off-windows-defender-lockbit-ransomware-sideloads-cobalt-strike-through-microsoft-security-tool
author: Bhabesh Raj
date: 2022-08-02
modified: 2022-09-28
tags:
    - attack.privilege-escalation
    - attack.persistence
    - attack.execution
    - attack.stealth
    - attack.t1574.001
logsource:
    product: windows
    service: security-mitigations
detection:
    selection:
        EventID:
            - 11
            - 12 # MDE: ExploitGuardNonMicrosoftSignedBlocked
        ProcessPath|endswith:
            - '\MpCmdRun.exe'
            - '\NisSrv.exe'
    condition: selection
falsepositives:
    - Unknown
level: high

Stages and Predicates

Stage 0: condition

selection

Stage 1: selection

selection:
    EventID:
        - 11
        - 12
    ProcessPath|endswith:
        - '\MpCmdRun.exe'
        - '\NisSrv.exe'

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
ProcessPathends_with
  • \MpCmdRun.exe
  • \NisSrv.exe