CVE-2017-2640 in Pidgin
Summary
by MITRE
An out-of-bounds write flaw was found in the way Pidgin before 2.12.0 processed XML content. A malicious remote server could potentially use this flaw to crash Pidgin or execute arbitrary code in the context of the pidgin process.
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Analysis
by VulDB Data Team • 08/19/2020
The vulnerability identified as CVE-2017-2640 represents a critical out-of-bounds write flaw within the Pidgin messaging client software. This issue affects versions prior to 2.12.0 and stems from insufficient input validation when processing XML content. The flaw exists in the XML parser implementation that handles structured data exchanges commonly used in instant messaging protocols, particularly those involving XMPP or similar extensible markup language formats. When Pidgin encounters malformed XML data from a remote server, the application fails to properly bounds-check array accesses during parsing operations, creating a condition where memory writes occur beyond allocated buffer boundaries.
The technical exploitation of this vulnerability follows a classic buffer overflow pattern that falls under CWE-787, which specifically addresses out-of-bounds writes. Attackers can craft malicious XML responses from a remote server that, when processed by the vulnerable Pidgin client, trigger memory corruption. The out-of-bounds write occurs during the parsing of XML elements, where the application attempts to write data beyond the intended memory allocation for parsed elements. This memory corruption can lead to unpredictable behavior including application crashes or more severe exploitation scenarios. The vulnerability is particularly dangerous because it allows remote code execution in the context of the pidgin process, meaning that successful exploitation could enable attackers to run arbitrary code with the same privileges as the messaging client itself.
From an operational perspective, this vulnerability presents a significant risk to users of Pidgin who engage with untrusted messaging servers or participate in conversations where malicious actors might control server-side content. The attack vector is particularly concerning because it requires only a malicious remote server to deliver the exploit, making it accessible to attackers who may not need direct access to the target system. The impact extends beyond simple denial of service, as the potential for remote code execution means that attackers could establish persistent access, steal credentials, or deploy additional malicious payloads. This vulnerability aligns with ATT&CK technique T1059.007 for command and scripting interpreter and T1068 for exploit for privilege escalation, as the compromised process context provides elevated access to system resources.
Organizations and individual users should prioritize immediate remediation by upgrading to Pidgin version 2.12.0 or later, which includes proper bounds checking and memory validation for XML processing operations. Additional mitigations include implementing network segmentation to limit exposure to untrusted servers, configuring firewall rules to restrict XML-based communications where possible, and monitoring for unusual network traffic patterns that might indicate exploitation attempts. Security teams should also consider implementing application whitelisting controls to prevent unauthorized versions of Pidgin from executing on managed systems. The vulnerability demonstrates the importance of robust input validation in messaging applications and highlights how seemingly benign XML parsing operations can become attack vectors when proper bounds checking is omitted.