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GHSA-43fj-qp3h-hrh5
No affected components available
Summary
The /api/auth/login endpoint contains a logic flaw that allows unauthenticated remote attackers to enumerate valid usernames by measuring the application's response time.
Details
The logic flaw can be located at the below point in source: https://github.com/Sync-in/server/blob/7868bb2b3025f92e6c38087456304758713971b2/backend/src/applications/users/services/users-queries.service.ts#L91-L95
Endpoints used for authentication should respond to the user with a consistent cadence, preventing remote actors from deriving sensitive information about an application based on backend behavior. In the case of authentication endpoints, this timing discrepancy is often caused by short-circuiting due to the lack of a matched user to compare against - as is the case with Sync-in.
Validation
TickTock Enum (Burp Suite Extension) was utilized to validate this finding. Authentication attempts with a valid username see a response from the application at around 350-400ms on average, while invalid usernames are returned at only 95-100ms on average. <img width="1302" height="284" alt="image" src="https://github.com/user-attachments/assets/31eeb72a-c3c2-4057-ac69-c0c92f0bbd4e" />
Impact
An unauthenticated remote attacker can enumerate valid usernames. This significantly weakens the application's security posture by facilitating targeted brute-force attacks, stuffing, social engineering, and a suite of other more targeted attacks.
The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker does not need any special privileges or access rights. No user interaction is needed for the attacker to exploit this vulnerability.
Limited exploitation activity has been observed. Close monitoring and planned remediation are recommended.
The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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