Commvault QLogin with PublicSharingUser and GUID Password (CVE-2025-57788)

calendar Oct 20, 2025 · attack.initial-access attack.t1078.001 detection.emerging-threats cve.2025-57788  ·
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Detects a qlogin.exe command attempting to authenticate as the internal _+_PublicSharingUser_ using a GUID as the password. This could be an indicator of an attacker exploiting CVE-2025-57788 to gain initial access using leaked credentials.

Sigma rule (View on GitHub)

 1title: Commvault QLogin with PublicSharingUser and GUID Password (CVE-2025-57788)
 2id: 917789e1-2c1f-4bf5-8c91-6f71a017f469
 3status: experimental
 4description: |
 5    Detects a qlogin.exe command attempting to authenticate as the internal `_+_PublicSharingUser_` using a GUID as the password.
 6    This could be an indicator of an attacker exploiting CVE-2025-57788 to gain initial access using leaked credentials.    
 7references:
 8    - https://labs.watchtowr.com/guess-who-would-be-stupid-enough-to-rob-the-same-vault-twice-pre-auth-rce-chains-in-commvault/
 9author: Swachchhanda Shrawan Poudel (Nextron Systems)
10date: 2025-10-20
11tags:
12    - attack.initial-access
13    - attack.t1078.001
14    - detection.emerging-threats
15    - cve.2025-57788
16logsource:
17    category: process_creation
18    product: windows
19detection:
20    selection:
21        CommandLine|contains|all:
22            - 'qlogin'
23            - '_+_PublicSharingUser_'
24        # Detects the use of a GUID as the password, which is indicative of an exploit attempt
25        CommandLine|re: '[A-F0-9]{8}-[A-F0-9]{4}-[A-F0-9]{4}-[A-F0-9]{4}-[A-F0-9]{12}'
26    condition: selection
27falsepositives:
28    - Legitimate administrative scripts that use the `_+_PublicSharingUser_` account for valid purposes.
29level: medium

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