CVE-2004-1378 in Jabber
Summary
by MITRE
The expat XML parser code, as used in the open source Jabber (jabberd) 1.4.3 and earlier, jadc2s 0.9.0 and earlier, and possibly other packages, allows remote attackers to cause a denial of service (application crash) via a malformed packet to a socket that accepts XML connections.
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Analysis
by VulDB Data Team • 06/07/2019
The CVE-2004-1378 vulnerability represents a critical denial of service weakness in the expat XML parser implementation that affected numerous open source applications including jabberd 1.4.3 and earlier versions, as well as jadc2s 0.9.0 and earlier. This vulnerability operates at the application layer and demonstrates how malformed XML data can be exploited to crash services that process XML communications. The flaw specifically targets XML parsers that fail to properly validate or handle malformed input, creating a pathway for remote attackers to disrupt service availability. The vulnerability is classified under CWE-129 as an insufficient input validation issue, where the system fails to properly validate the bounds of input data before processing. The attack vector involves sending specially crafted malformed XML packets to sockets that accept XML connections, exploiting the parser's inadequate error handling mechanisms. This weakness falls squarely within the ATT&CK technique T1499.004 for Network Denial of Service, as it enables adversaries to disrupt network services through malformed data injection.
The technical implementation of this vulnerability stems from the expat parser's failure to properly handle malformed XML structures that contain invalid character sequences or improperly nested elements. When the parser encounters such malformed data, it does not gracefully handle the error condition but instead crashes or terminates abnormally, causing the application to become unavailable to legitimate users. The vulnerability is particularly dangerous because XML parsing is a fundamental operation in many networked applications, and the parser's failure to validate input properly means that any application using expat for XML processing becomes susceptible to this attack. The crash occurs during the parsing phase when the XML processor attempts to interpret malformed data structures, specifically targeting memory management and state handling within the parser's internal routines. This type of vulnerability is categorized as a buffer over-read or improper input handling issue where the parser does not properly validate the structure of incoming XML data before attempting to process it.
The operational impact of CVE-2004-1378 extends beyond simple service disruption to potentially compromise the availability of critical communication services in instant messaging and other XML-based applications. When exploited, the vulnerability can cause applications to crash repeatedly, requiring manual restarts and potentially leading to extended service outages. The vulnerability affects systems where XML processing is integral to the application's functionality, particularly those that accept external XML data from untrusted sources without proper validation. Attackers can leverage this weakness to perform sustained denial of service attacks against Jabber servers and similar applications, making it a significant concern for network administrators responsible for maintaining service availability. The vulnerability's widespread impact is evident in its presence across multiple software packages that utilize the expat parser, indicating that organizations running any software with affected versions are at risk of service disruption. This weakness can be particularly problematic in environments where continuous availability is critical, as the crash behavior can be triggered by a single malformed packet, making it an attractive attack vector for adversaries seeking to disrupt communications.
Mitigation strategies for CVE-2004-1378 primarily involve upgrading to patched versions of the affected software packages that contain proper input validation and error handling mechanisms. System administrators should prioritize updating jabberd to versions 1.4.4 or later, jadc2s to 0.9.1 or later, and any other applications that utilize vulnerable versions of the expat parser. The implementation of input validation controls at the application level can provide additional protection by sanitizing XML data before it reaches the parser, though this approach requires careful implementation to avoid introducing new vulnerabilities. Network-level protections such as XML firewalls or content filtering systems can help detect and block malformed XML packets before they reach vulnerable applications. Organizations should also implement monitoring and alerting systems to detect unusual application crash patterns that may indicate exploitation attempts. The vulnerability's remediation aligns with security best practices outlined in the OWASP Top Ten and NIST cybersecurity frameworks, emphasizing the importance of proper input validation and error handling in preventing denial of service attacks. Regular vulnerability assessments and security audits should be conducted to identify other potentially vulnerable applications that may be using older versions of the expat parser, ensuring comprehensive protection against similar weaknesses in the software ecosystem.