CVE-2004-0409 in Xchat
Summary
by MITRE
Stack-based buffer overflow in the Socks-5 proxy code for XChat 1.8.0 to 2.0.8, with socks5 traversal enabled, allows remote attackers to execute arbitrary code.
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Analysis
by VulDB Data Team • 01/02/2025
The vulnerability identified as CVE-2004-0409 represents a critical stack-based buffer overflow flaw within the SOCKS-5 proxy implementation of XChat client versions ranging from 1.8.0 through 2.0.8. This vulnerability specifically manifests when the socks5 traversal feature is enabled, creating a dangerous condition that remote attackers can exploit to gain arbitrary code execution privileges on affected systems. The flaw resides in the proxy handling code that processes incoming SOCKS-5 connection requests, where insufficient input validation leads to memory corruption through improper buffer management.
The technical nature of this vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions where insufficient bounds checking allows attackers to overwrite adjacent memory locations including return addresses and control data. The flaw occurs during the processing of SOCKS-5 authentication and connection establishment phases when the application fails to properly validate the length of incoming data structures. Attackers can craft malicious SOCKS-5 proxy requests containing oversized data payloads that exceed the allocated stack buffer space, causing the program to overwrite adjacent memory regions and potentially redirect execution flow to attacker-controlled code.
From an operational perspective, this vulnerability presents significant risks to users who have enabled SOCKS-5 proxy functionality in their XChat clients. The attack vector requires remote exploitation through network-based communication with the vulnerable application, making it particularly dangerous in environments where users may connect to untrusted proxy servers or where malicious actors can intercept network traffic. Successful exploitation results in complete system compromise, as attackers can execute arbitrary commands with the privileges of the affected user, potentially leading to data theft, system infiltration, or further network propagation. The vulnerability's impact extends beyond individual user systems to potential network-wide compromise when users inadvertently connect to malicious proxy servers.
The mitigation strategies for this vulnerability primarily focus on immediate remediation through software updates and patches provided by the software vendor. System administrators should prioritize updating XChat installations to versions that contain fixed proxy handling code with proper input validation and buffer size checking mechanisms. Additionally, disabling SOCKS-5 proxy functionality when not required provides a temporary workaround while awaiting official patches. Network security controls including firewall rules that restrict access to SOCKS-5 proxy ports and intrusion detection systems capable of identifying malformed proxy requests can help detect and prevent exploitation attempts. The vulnerability also highlights the importance of input validation in network protocol implementations and demonstrates how seemingly minor security flaws in proxy handling code can result in complete system compromise, aligning with tactics described in the attack pattern taxonomy where buffer overflows represent common initial access vectors in exploit chains.