CVE-2006-3669 in Mercury
Summary
by MITRE
Mercury Messenger, possibly 1.7.1.1 and other versions, when running on a multi-user Mac OS X platform, stores chat logs with world-readable permissions within the /Users directory, which allows local users to read the chat logs from other users.
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Analysis
by VulDB Data Team • 07/31/2018
Mercury Messenger represents a significant security vulnerability in macOS environments where multiple users share a single system instance. This flaw manifests specifically in versions including 1.7.1.1 and potentially other iterations of the messaging application. The vulnerability stems from improper file permission handling during the storage of chat log data, creating a critical access control weakness that undermines user privacy and system security. The affected application fails to implement appropriate discretionary access control mechanisms when creating chat log files within the standard user directory structure.
The technical implementation of this vulnerability involves the application's failure to set restrictive file permissions on chat log files it generates. When Mercury Messenger creates chat log entries on multi-user macOS systems, it stores these files in the /Users directory with default permissions that allow read access to all system users. This misconfiguration creates a persistent security exposure where any local user can access another user's chat logs simply by navigating to the appropriate directory structure and reading the stored files. The vulnerability operates at the file system level, exploiting fundamental Unix-style permission models that are expected to provide user isolation and data protection.
The operational impact of this vulnerability extends beyond simple privacy concerns to encompass potential data leakage and information disclosure risks. Local users who gain access to chat logs can potentially extract sensitive personal information, communication patterns, and private conversations between other system users. This exposure could facilitate social engineering attacks, identity theft, or the compromise of confidential communications that users reasonably expect to remain private. The vulnerability is particularly concerning in shared computing environments such as offices, educational institutions, or public computer labs where multiple individuals utilize the same system resources.
From a cybersecurity framework perspective, this vulnerability aligns with CWE-732: Incorrect Permission Assignment for Critical Resource, which specifically addresses situations where security-critical resources are created with insecure permissions. The flaw also relates to ATT&CK technique T1005: Data from Local System, which describes methods adversaries use to collect data from local system files. Additionally, this issue represents a violation of the principle of least privilege, where the application unnecessarily grants excessive permissions to files that should remain private to individual users. The vulnerability demonstrates a failure in the application's secure coding practices and access control implementation.
Mitigation strategies for this vulnerability require both immediate and long-term approaches to address the core permission handling flaw. System administrators should immediately review and correct file permissions on existing chat log files to ensure they are restricted to the appropriate user ownership and permissions. The application itself must be updated to implement proper discretionary access control when creating chat log files, ensuring that these files are created with restrictive permissions that limit access to the user who generated them. Organizations should also consider implementing additional monitoring to detect unauthorized access attempts to user chat logs and establish proper security awareness training for users about the risks of sharing systems. The most effective long-term solution involves updating to patched versions of Mercury Messenger that properly implement secure file creation practices and adhere to established security guidelines for multi-user system environments.