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User Enumeration Vulnerability in login page (CWE-204) #9

@cydtseng

Description

@cydtseng

Description

A user enumeration vulnerability exists in the mee-admin 1.6 application at /mee/login. By submitting login attempts with different usernames, an attacker can distinguish between valid and invalid accounts based on the differing responses returned by the server. This allows an attacker to determine which usernames exist in the system.

Affected version

mee-admin 1.6

Steps to reproduce

  • For local setup, navigate to http://localhost/mee/login.
  • Enter a non-existent username and any password.
  • Observe the error message or response behavior.
  • Enter a known valid username (e.g., an existing user) and any password.
  • Compare the responses. The difference in responses allows determining whether a given username is valid.

Observed Behavior

The application returns a unique response for invalid usernames, making it possible to identify existing user accounts.

Expected Behavior

The application should return a uniform, generic error message or response for all invalid login attempts, regardless of whether the username is valid.

Security Impact

This vulnerability (CWE-204: Observable Response Discrepancy) enables attackers to enumerate valid usernames. With knowledge of valid usernames, attackers can conduct targeted brute-force or credential-stuffing attacks, increasing the risk of unauthorized access.

Recommendation

Return a generic error message (e.g., "Invalid credentials") for all unsuccessful login attempts.
Consider implementing rate limiting, CAPTCHAs, or other mechanisms to deter automated enumeration.
Ensure that timing, status codes, or other response attributes do not differ between valid and invalid accounts.

Additional Information

CWE-204: https://cwe.mitre.org/data/definitions/204.html

Thank you for your time and consideration in addressing this issue.

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