KDC RC4-HMAC Downgrade CVE-2022-37966

calendar Sep 22, 2025 · attack.privilege-escalation  ·
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Detects the exploitation of a security bypass and elevation of privilege vulnerability with Authentication Negotiation by using weak RC4-HMAC negotiation

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 1title: KDC RC4-HMAC Downgrade CVE-2022-37966
 2id: e6f81941-b1cd-4766-87db-9fc156f658ee
 3status: test
 4description: Detects the exploitation of a security bypass and elevation of privilege vulnerability with Authentication Negotiation by using weak RC4-HMAC negotiation
 5references:
 6    - https://support.microsoft.com/en-us/topic/kb5021131-how-to-manage-the-kerberos-protocol-changes-related-to-cve-2022-37966-fd837ac3-cdec-4e76-a6ec-86e67501407d
 7author: Florian Roth (Nextron Systems)
 8date: 2022-11-09
 9modified: 2025-09-22
10tags:
11    - attack.privilege-escalation
12logsource:
13    product: windows
14    service: system
15detection:
16    selection:
17        EventID: 42
18        Provider_Name:
19            - 'Kerberos-Key-Distribution-Center'
20            - 'Microsoft-Windows-Kerberos-Key-Distribution-Center'
21        Level: 2  # Error
22    condition: selection
23falsepositives:
24    - Unknown
25level: high

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