CVE-2004-0646 in JRun
Summary
by MITRE
Buffer overflow in the WriteToLog function for JRun 3.0 through 4.0 web server connectors, such as (1) mod_jrun and (2) mod_jrun20 for Apache, with verbose logging enabled, allows remote attackers to execute arbitrary code via a long HTTP header Content-Type field or other fields.
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Analysis
by VulDB Data Team • 11/19/2024
The vulnerability identified as CVE-2004-0646 represents a critical buffer overflow flaw within the JRun web server connectors that affected versions 3.0 through 4.0. This security weakness specifically targets the WriteToLog function implementation within the mod_jrun and mod_jrun20 Apache modules, creating a pathway for remote code execution when verbose logging is enabled. The flaw stems from insufficient input validation and boundary checking mechanisms that fail to properly handle excessively long HTTP header values, particularly the Content-Type field and other header parameters. The vulnerability operates at the intersection of software security and web server configuration, where the combination of verbose logging and inadequate buffer management creates a exploitable condition that can be leveraged by remote attackers to gain unauthorized system access.
The technical implementation of this buffer overflow occurs when the WriteToLog function processes HTTP headers without enforcing proper length constraints on the Content-Type field or similar header parameters. When an attacker submits a malformed HTTP request containing an excessively long header value, the function attempts to write this data to a fixed-size buffer that cannot accommodate the overflow. This results in memory corruption that can be manipulated to overwrite critical program execution structures, including return addresses and function pointers. The vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and CWE-122, which covers heap-based buffer overflow scenarios. The attack vector operates through the Apache web server's module architecture where mod_jrun and mod_jrun20 act as intermediaries between the web server and the JRun application server, making this a particularly dangerous flaw in enterprise web infrastructure deployments.
The operational impact of this vulnerability extends beyond simple code execution to encompass complete system compromise and potential data breach scenarios. Remote attackers can leverage this flaw to inject malicious code that executes with the privileges of the web server process, typically running with elevated system permissions. This creates opportunities for attackers to establish persistent backdoors, escalate privileges to system administrators, or extract sensitive information from the affected systems. The vulnerability's exploitation is particularly concerning in production environments where verbose logging is enabled for troubleshooting purposes, as this configuration becomes the attack surface for malicious actors. The flaw demonstrates how seemingly innocuous logging features can become security liabilities when combined with insufficient input validation, creating a persistent threat that can remain undetected for extended periods.
Mitigation strategies for CVE-2004-0646 require immediate attention through multiple defensive measures that address both the immediate vulnerability and broader security posture. The primary recommendation involves disabling verbose logging in production environments where the affected JRun connectors are deployed, as this configuration eliminates the attack surface entirely. System administrators should also implement input validation controls at the web server level to limit the length of HTTP header values before they reach the vulnerable JRun modules. Network-level protections including firewall rules and intrusion detection systems can help detect and block suspicious header content patterns that may indicate exploitation attempts. Additionally, organizations should consider implementing web application firewalls that can filter out malicious header content and provide additional layers of defense against similar buffer overflow vulnerabilities. The remediation process should also include updating to patched versions of JRun 4.0 or later, as these releases contain proper input validation and buffer management fixes. This vulnerability serves as a critical reminder of the importance of secure coding practices and proper input validation in web server components, aligning with ATT&CK technique T1059 for command and scripting interpreter and T1203 for exploitation for client execution, highlighting the need for comprehensive security controls across all system layers.