CVE-2008-6393 in PSI
Summary
by MITRE
PSI Jabber client before 0.12.1 allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via a file transfer request with a negative value in a SOCKS5 option, which bypasses a signed integer check and triggers an integer overflow and a heap-based buffer overflow.
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Analysis
by VulDB Data Team • 05/24/2025
The vulnerability identified as CVE-2008-6393 affects the PSI Jabber client version 0.12.1 and earlier, representing a critical security flaw that enables remote attackers to execute both denial of service attacks and potential arbitrary code execution. This vulnerability specifically targets the file transfer functionality within the Jabber client implementation, exploiting a weakness in the SOCKS5 protocol handling mechanism that governs network connections for file transfers.
The technical exploitation mechanism involves crafting a malicious file transfer request that contains a negative value within the SOCKS5 option parameters. This seemingly simple manipulation bypasses existing signed integer checks that should have prevented such invalid values from being processed. The flaw occurs when the application attempts to convert this negative value into an unsigned integer type, triggering an integer overflow condition. The overflow subsequently leads to a heap-based buffer overflow, where the application writes data beyond the allocated memory boundaries, potentially corrupting adjacent memory structures.
From an operational perspective, this vulnerability represents a significant risk to users of the PSI Jabber client, as it can be exploited remotely without requiring any authentication or privileged access. The denial of service component causes the client application to crash and terminate unexpectedly, disrupting communication services for legitimate users. However, the more dangerous aspect involves the potential for arbitrary code execution, which could allow attackers to gain control over the victim's system, execute malicious commands, or install persistent backdoors.
The vulnerability maps directly to CWE-190, which specifically addresses integer overflow conditions, and CWE-121, which covers stack-based buffer overflow issues. Additionally, this flaw aligns with ATT&CK technique T1059.007 for command and scripting interpreter, as the potential for arbitrary code execution could enable attackers to establish persistent access through command execution capabilities. The attack surface is particularly concerning because it leverages the legitimate file transfer functionality that users frequently employ, making the exploitation more likely to succeed in real-world scenarios.
Organizations and individuals using the PSI Jabber client should immediately implement mitigation strategies including updating to version 0.12.1 or later, which contains the necessary patches to address the integer overflow and buffer overflow conditions. Network administrators should consider implementing firewall rules that restrict file transfer capabilities or monitor for suspicious SOCKS5 traffic patterns that might indicate exploitation attempts. System hardening measures such as enabling address space layout randomization and stack canaries can provide additional protection layers against potential exploitation attempts. Regular security audits of instant messaging clients and communication tools should be conducted to identify similar vulnerabilities that might exist in other components of the communication infrastructure.