CVE-2010-2528 in Pidgin
Summary
by MITRE
The clientautoresp function in family_icbm.c in the oscar protocol plugin in libpurple in Pidgin before 2.7.2 allows remote authenticated users to cause a denial of service (NULL pointer dereference and application crash) via an X-Status message that lacks the expected end tag for a (1) desc or (2) title element.
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Analysis
by VulDB Data Team • 09/21/2021
The vulnerability identified as CVE-2010-2528 represents a critical denial of service flaw within the oscar protocol plugin of Pidgin messaging client. This issue affects versions prior to 2.7.2 and stems from improper handling of X-Status messages within the clientautoresp function located in family_icbm.c. The vulnerability specifically targets the parsing logic for desc and title elements within X-Status messages, creating a condition where a malformed message can trigger a NULL pointer dereference. The flaw occurs when the plugin encounters an X-Status message that lacks the expected end tag for either the desc or title element, leading to an application crash that effectively denies service to legitimate users.
From a technical perspective, this vulnerability operates as a NULL pointer dereference, which is classified as CWE-476 within the Common Weakness Enumeration framework. The issue manifests when the oscar protocol plugin attempts to process an X-Status message that contains incomplete XML structure, specifically missing closing tags for desc or title elements. The clientautoresp function fails to properly validate the message structure before attempting to dereference pointers associated with these elements, resulting in a segmentation fault that crashes the entire Pidgin application. This type of vulnerability falls under the ATT&CK technique T1499.004 for Network Denial of Service, as it enables remote authenticated attackers to disrupt service availability.
The operational impact of this vulnerability extends beyond simple application instability, as it can be exploited by authenticated remote attackers who have access to the messaging service. Attackers can craft malicious X-Status messages that, when processed by the vulnerable Pidgin client, will cause the application to terminate unexpectedly. This disruption affects not only the targeted user's ability to communicate but also potentially impacts the broader messaging ecosystem if the affected client is part of a larger network. The vulnerability is particularly concerning because it requires only authentication to the messaging service, making it accessible to anyone with valid credentials, and can be executed repeatedly to maintain the denial of service condition.
Mitigation strategies for CVE-2010-2528 focus primarily on updating to Pidgin version 2.7.2 or later, which includes proper input validation and error handling for X-Status message processing. Additionally, administrators should implement network monitoring to detect unusual patterns of X-Status message traffic that might indicate exploitation attempts. The fix implemented in version 2.7.2 involves robust validation of XML message structures before pointer dereference operations, ensuring that all expected elements are properly closed and formatted before processing. Organizations should also consider implementing message filtering mechanisms that can identify and block malformed X-Status messages at the network level, providing an additional layer of protection against this specific vulnerability while maintaining normal messaging functionality.