CVE-2010-1624 in Pidgin
Summary
by MITRE
The msn_emoticon_msg function in slp.c in the MSN protocol plugin in libpurple in Pidgin before 2.7.0 allows remote authenticated users to cause a denial of service (NULL pointer dereference and application crash) via a custom emoticon in a malformed SLP message.
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Analysis
by VulDB Data Team • 03/18/2021
The vulnerability described in CVE-2010-1624 represents a critical denial of service flaw within the messaging infrastructure of Pidgin, a widely used instant messaging client that supports multiple protocols including MSN. This vulnerability specifically targets the MSN protocol plugin implementation in libpurple, which serves as the core messaging library for Pidgin's protocol handling capabilities. The flaw manifests in the msn_emoticon_msg function located within the slp.c file, which processes SLP (Session Location Protocol) messages that are fundamental to MSN messaging operations. The vulnerability affects all versions of Pidgin prior to 2.7.0, making it a significant concern for users who have not yet updated their installations.
The technical exploitation of this vulnerability occurs through a carefully crafted malformed SLP message containing a custom emoticon that triggers a NULL pointer dereference within the msn_emoticon_msg function. This type of flaw falls under the CWE-476 category of NULL Pointer Dereference, which is a common vulnerability pattern where an application attempts to access memory through a pointer that has not been properly initialized or validated. When an authenticated remote user sends such a malformed message, the application fails to properly validate the emoticon data structure before attempting to process it, resulting in the dereferencing of a NULL pointer. This programming error causes the application to crash immediately, terminating the Pidgin process and rendering the messaging service unavailable to the user.
The operational impact of this vulnerability extends beyond simple service interruption as it provides an authenticated attacker with a reliable method to disrupt communication services for targeted users. Since the attack requires only authentication to the MSN protocol, which is typically as simple as providing valid credentials, the vulnerability can be exploited by anyone with access to a user's MSN account. This makes it particularly dangerous in environments where Pidgin is used for business communications or where users may be targeted by malicious actors seeking to disrupt their messaging capabilities. The vulnerability also aligns with ATT&CK technique T1499.004 for Network Denial of Service, as it specifically targets the availability of network messaging services through application-level exploitation.
The root cause of this vulnerability stems from inadequate input validation within the MSN protocol plugin's emoticon processing logic. When the msn_emoticon_msg function receives an SLP message with a malformed emoticon, it fails to properly validate the structure of the emoticon data before attempting to process it, leading to the NULL pointer dereference. This represents a classic example of insufficient error handling and input sanitization in protocol implementation code. The vulnerability demonstrates how seemingly benign features like emoticon support can become attack vectors when proper validation mechanisms are missing from the implementation. The flaw is particularly concerning because it affects the core messaging functionality of Pidgin, which is used by millions of users worldwide for both personal and professional communications, making it a prime target for attackers seeking to disrupt messaging services at scale.
Organizations and individual users should immediately update to Pidgin version 2.7.0 or later to remediate this vulnerability, as this release includes proper input validation and error handling for emoticon processing. Additionally, network administrators should consider implementing monitoring for suspicious SLP message patterns and ensure that all messaging applications are kept current with security patches. The vulnerability serves as a reminder of the importance of proper input validation in protocol implementations and the critical need for thorough security testing of messaging applications that handle external data from authenticated users. This type of vulnerability is particularly relevant to the broader field of secure coding practices and highlights the importance of following secure development lifecycle principles to prevent similar issues in other messaging and communication platforms.