Potential CVE-2021-42278 Exploitation Attempt

The attacker creates a computer object using those permissions with a password known to her. After that she clears the attribute ServicePrincipalName on the computer object. Because she created the object (CREATOR OWNER), she gets granted additional permissions and can do many changes to the object.

Sigma rule (View on GitHub)

 1title: Potential CVE-2021-42278 Exploitation Attempt
 2id: 44bbff3e-4ca3-452d-a49a-6efa4cafa06f
 3related:
 4    - id: e80a0fee-1a62-4419-b31e-0d0db6e6013a
 5      type: similar
 6status: test
 7description: |
 8    The attacker creates a computer object using those permissions with a password known to her.
 9    After that she clears the attribute ServicePrincipalName on the computer object.
10    Because she created the object (CREATOR OWNER), she gets granted additional permissions and can do many changes to the object.    
11references:
12    - https://cloudbrothers.info/en/exploit-kerberos-samaccountname-spoofing/
13author: frack113
14date: 2021-12-15
15modified: 2023-04-14
16tags:
17    - attack.credential-access
18    - attack.t1558.003
19    - cve.2021-42278
20    - detection.emerging-threats
21logsource:
22    product: windows
23    service: system
24detection:
25    selection:
26        Provider_Name: 'Microsoft-Windows-Kerberos-Key-Distribution-Center'  # Active Directory
27        EventID:
28            - 35 # PAC without attributes
29            - 36 # Ticket without a PAC
30            - 37 # Ticket without Requestor
31            - 38 # Requestor Mismatch
32    condition: selection
33falsepositives:
34    - Unknown
35fields:
36    - samAccountName
37level: medium

References

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