SigmaHQ/rules/windows/builtin/win_net_ntlm_downgrade.yml

action: global
title: NetNTLM Downgrade Attack
id: d67572a0-e2ec-45d6-b8db-c100d14b8ef2
description: Detects NetNTLM downgrade attack
references:
    - https://www.optiv.com/blog/post-exploitation-using-netntlm-downgrade-attacks
author: Florian Roth
date: 2018/03/20
modified: 2021/02/24
tags:
    - attack.defense_evasion
    - attack.t1089          # an old one
    - attack.t1562.001
    - attack.t1112
detection:
    condition: 1 of them
falsepositives:
    - Unknown
level: critical
---
logsource:
    product: windows
    category: registry_event
detection:
    selection1:
        TargetObject|contains|all: 
            - 'SYSTEM\'
            - 'ControlSet'
            - '\Control\Lsa'
        TargetObject|endswith:
            - '\lmcompatibilitylevel'
            - '\NtlmMinClientSec'
            - '\RestrictSendingNTLMTraffic'
            
---
# Windows Security Eventlog: Process Creation with Full Command Line
logsource:
    product: windows
    service: security
    definition: 'Requirements: Audit Policy : Object Access > Audit Registry (Success)'
detection:
    selection:
        EventID: 4657
        ObjectName|startswith: '\REGISTRY\MACHINE\SYSTEM\\*ControlSet*\Control\Lsa'
        ObjectValueName: 
            - 'LmCompatibilityLevel'
            - 'NtlmMinClientSec'
            - 'RestrictSendingNTLMTraffic'
    condition: selection
falsepositives:
    - Unknown
level: critical