CVE-2005-0080 in mailman
Summary
by MITRE
The 55_options_traceback.dpatch patch for mailman 2.1.5 in Ubuntu 4.10 displays a different error message depending on whether the e-mail address is subscribed to a private list, which allows remote attackers to determine the list membership for a given e-mail address.
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Analysis
by VulDB Data Team • 03/14/2017
The vulnerability described in CVE-2005-0080 represents a classic information disclosure flaw that emerged in the mailman mailing list management system version 2.1.5. This issue specifically affects Ubuntu 4.10 distributions where the 55_options_traceback.dpatch patch was implemented. The flaw manifests through inconsistent error messaging that reveals whether a given email address is subscribed to a private mailing list, creating a significant privacy and security risk for users who rely on list confidentiality. The vulnerability operates at the application level and demonstrates poor error handling practices that inadvertently expose sensitive information about list membership.
The technical mechanism behind this vulnerability involves the mailman system's response to subscription-related requests. When a remote attacker submits a request for a specific email address on a private list, the system generates different error messages depending on whether that address is actually subscribed to the list. If the address exists in the list, the system returns one type of error message indicating a successful subscription status. However, when the address is not found in the list, a different error message is displayed that clearly indicates the address is not subscribed. This differential response creates a reliable method for attackers to enumerate list members without authorization.
This vulnerability directly maps to CWE-200, which describes "Information Exposure Through Error Message" and falls under the broader category of information disclosure weaknesses. The attack pattern aligns with techniques described in the ATT&CK framework under T1212, which covers "Exploitation for Credential Access" and T1566, which covers "Phishing" as attackers can use this information to craft more targeted social engineering campaigns. The flaw essentially provides an automated reconnaissance capability that bypasses normal access controls and subscription verification mechanisms.
The operational impact of this vulnerability extends beyond simple information disclosure, as it enables attackers to perform membership enumeration attacks against private mailing lists. This capability can be particularly damaging for organizations that rely on private lists for sensitive communications, as it allows unauthorized parties to identify who has access to confidential discussions. The vulnerability affects both the confidentiality and integrity of the mailing list system, as it undermines the expected privacy controls that users rely on when subscribing to private lists. Organizations using mailman 2.1.5 with this patch would be vulnerable to systematic membership discovery attacks that could lead to targeted phishing campaigns or other forms of social engineering.
The recommended mitigation strategy involves implementing consistent error handling throughout the mailman system to ensure that all subscription-related requests return identical error messages regardless of whether the email address is subscribed to the list. This approach aligns with security best practices outlined in the OWASP Top Ten and follows the principle of least information disclosure. Organizations should also consider upgrading to newer versions of mailman that have addressed this vulnerability, as the patch in Ubuntu 4.10 was a temporary workaround. Additionally, implementing proper access controls and monitoring for unusual subscription requests can help detect and prevent enumeration attacks. The vulnerability serves as a reminder of the importance of maintaining consistent error handling practices and avoiding information leakage through application responses, particularly in systems that handle sensitive user data and communications.