CVE-2000-1002 in Communigate Pro
Summary
by MITRE
POP3 daemon in Stalker CommuniGate Pro 3.3.2 generates different error messages for invalid usernames versus invalid passwords, which allows remote attackers to determine valid email addresses on the server for SPAM attacks.
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Analysis
by VulDB Data Team • 10/12/2025
The vulnerability described in CVE-2000-1002 affects the POP3 daemon implementation within Stalker CommuniGate Pro version 3.3.2, representing a classic information disclosure flaw that undermines system security through improper error handling. This issue stems from the daemon's inconsistent response behavior when processing authentication attempts, specifically creating distinguishable error messages for different types of authentication failures. The flaw enables attackers to perform user enumeration attacks by observing the varying error responses returned by the server when attempting to authenticate with different username and password combinations, thereby exposing the existence of valid email accounts.
From a technical perspective, this vulnerability operates at the application layer and demonstrates a clear violation of secure error handling principles. The daemon's implementation fails to provide consistent error messaging regardless of whether the authentication failure results from a non-existent username or an incorrect password. This inconsistency creates a side-channel information leak that directly exposes the system's user directory structure to external actors. The vulnerability is classified under CWE-209, which addresses the improper handling of error messages that can reveal system information to unauthorized parties, and aligns with ATT&CK technique T1087.001 for account discovery through enumeration of valid accounts.
The operational impact of this vulnerability extends beyond simple information disclosure, as it directly enables spammer activities and facilitates targeted attacks against the system's user base. Attackers can systematically test username combinations to identify valid email addresses, which then can be used for spam campaigns, phishing attacks, or further exploitation attempts. The vulnerability effectively undermines the security of the email infrastructure by providing attackers with a straightforward method to enumerate valid user accounts without requiring any special privileges or advanced techniques. This enumeration capability significantly increases the attack surface and provides malicious actors with valuable intelligence for subsequent phases of their operations.
Mitigation strategies for CVE-2000-1002 should focus on implementing consistent error handling across authentication mechanisms to prevent information leakage. The most effective approach involves configuring the POP3 daemon to return identical error messages for both invalid username and invalid password scenarios, ensuring that no distinction is made between these failure conditions in the response. System administrators should also implement account lockout mechanisms and rate limiting to prevent automated enumeration attempts. Additionally, network-level protections such as firewalls and intrusion detection systems can help detect and block suspicious authentication patterns. The vulnerability highlights the importance of following secure coding practices and adhering to the principle of least information disclosure, where systems should never reveal more information than necessary about their internal state or configuration to prevent attackers from gaining insights into system structure and user base.