NetNTLM Downgrade Attack - Registry

 1title: NetNTLM Downgrade Attack - Registry
 2id: d67572a0-e2ec-45d6-b8db-c100d14b8ef2
 3status: test
 4description: Detects NetNTLM downgrade attack
 5references:
 6    - https://web.archive.org/web/20171113231705/https://www.optiv.com/blog/post-exploitation-using-netntlm-downgrade-attacks
 7    - https://www.ultimatewindowssecurity.com/wiki/page.aspx?spid=NSrpcservers
 8author: Florian Roth (Nextron Systems), wagga, Nasreddine Bencherchali (Splunk STRT)
 9date: 2018-03-20
10modified: 2024-12-03
11tags:
12    - attack.persistence
13    - attack.defense-evasion
14    - attack.t1562.001
15    - attack.t1112
16logsource:
17    product: windows
18    category: registry_event
19detection:
20    selection_regkey:
21        TargetObject|contains|all:
22            - 'SYSTEM\'
23            - 'ControlSet'
24            - '\Control\Lsa'
25    selection_value_lmcompatibilitylevel:
26        TargetObject|endswith: '\lmcompatibilitylevel'
27        Details:
28            - 'DWORD (0x00000000)'
29            - 'DWORD (0x00000001)'
30            - 'DWORD (0x00000002)'
31    selection_value_ntlmminclientsec:
32        TargetObject|endswith: '\NtlmMinClientSec'
33        Details:
34            - 'DWORD (0x00000000)' # No Security
35            - 'DWORD (0x00000010)' # Only Integrity
36            - 'DWORD (0x00000020)' # Only confidentiality
37            - 'DWORD (0x00000030)' # Both Integrity and confidentiality
38    selection_value_restrictsendingntlmtraffic:
39        # Note: The obvious values with issues are 0x00000000 (allow all) and 0x00000001 (audit).
40        # 0x00000002 can be secure but only if "ClientAllowedNTLMServers" is properly configured
41        # Hence all values should be monitored and investigated
42        TargetObject|endswith: '\RestrictSendingNTLMTraffic'
43    condition: selection_regkey and 1 of selection_value_*
44falsepositives:
45    - Services or tools that set the values to more restrictive values
46level: high