CVE-2008-7255 in aMSN
Summary
by MITRE
login_screen.tcl in aMSN (aka Alvaro s Messenger) before 0.97.1 saves a password after logout, which allows physically proximate attackers to hijack a session by visiting an unattended workstation.
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Analysis
by VulDB Data Team • 01/29/2019
The vulnerability identified as CVE-2008-7255 affects aMSN, also known as Alvaro s Messenger, a popular instant messaging client for the AOL Instant Messenger protocol. This security flaw exists in the login_screen.tcl script component of the application and represents a critical session management weakness that undermines the fundamental security assumptions of user authentication and session handling. The vulnerability specifically impacts versions prior to 0.97.1, indicating that this was a known issue that required a specific patch release to address the underlying flaw.
The technical implementation of this vulnerability stems from improper session cleanup mechanisms within the application's authentication flow. When a user logs out of the aMSN client, the system fails to properly clear sensitive authentication data from memory or temporary storage locations. This design flaw allows attackers with physical access to the workstation to exploit the saved credentials by simply visiting the unattended machine and initiating a new session. The vulnerability demonstrates a failure in following secure coding practices that require sensitive data to be explicitly cleared from memory upon user logout or session termination.
From an operational perspective, this vulnerability creates a significant risk for users who work in shared or public environments where physical access to workstations cannot be guaranteed. The attack vector requires only physical proximity to the target machine, making it particularly dangerous in corporate, academic, or public computing environments where users may leave their workstations unattended. This weakness directly violates the principle of least privilege and user authentication integrity, as it allows unauthorized individuals to assume the identity of legitimate users without requiring any network connectivity or advanced exploitation techniques. The vulnerability essentially creates a backdoor that bypasses normal authentication mechanisms by leveraging the cached credentials stored in memory.
The security implications extend beyond simple session hijacking to encompass potential data breaches and unauthorized access to user communications. Attackers could access private conversations, contact lists, and potentially sensitive information transmitted through the messaging platform. This vulnerability aligns with CWE-522, which addresses Insufficiently Protected Credentials, and represents a failure to implement proper credential handling practices. The issue also maps to ATT&CK technique T1548.001, which covers Abuse of Functionality for privilege escalation and session hijacking. Organizations using aMSN or similar instant messaging clients should consider implementing additional physical security measures, such as automatic screen locking, and users should be educated about the importance of securing their workstations when stepping away from their computers.
Mitigation strategies for this vulnerability require both immediate application updates and user awareness training. The primary solution involves upgrading to aMSN version 0.97.1 or later, which contains the necessary code modifications to properly clear authentication data upon user logout. System administrators should implement regular patch management procedures to ensure all instant messaging clients are updated with the latest security fixes. Additionally, organizations should enforce policies requiring users to lock their workstations when leaving them unattended, and consider implementing automatic screen lock timeouts. The vulnerability highlights the importance of proper session management and credential handling in client applications, particularly those handling sensitive communications data. Users should also be trained to recognize the risks associated with leaving workstations unattended and to understand that physical access to a machine can bypass traditional network-based security controls.