Suspicious Registry Key Set (MaxMpxCt)

 1title: 'Suspicious Registry Key Set (MaxMpxCt)'
 2id: 4bd730d9-37d6-4a87-b392-ffb9ab52bf21
 3status: experimental
 4description: Detects registry value set to change MaxMpxCt settings. BlackCat does this to increase the number of outstanding requests allowed, such as SMB requests to distribute ransomware through an environment.
 5references:
 6    - https://www.microsoft.com/en-us/security/blog/2022/06/13/the-many-lives-of-blackcat-ransomware/
 7author: Micah Babinski
 8date: 2022/12/04
 9tags:
10    - attack.command_and_control
11    - attack.defense_evasion
12    - attack.t1105
13    - attack.t1562
14logsource:
15    category: registry_set
16    product: windows
17detection:
18    selection:
19        EventType: SetValue
20        TargetObject: 'HKLM\System\CurrentControlSet\Services\LanmanServer\Parameters\MaxMpxCt'
21        Details: 'DWORD (0x0000ffff)'
22    condition: selection
23falsepositives:
24    - Unknown
25level: high```