CVE-2011-2206 in DJabberd
Summary
by MITRE
XMLParser.pm in DJabberd before 0.85 allows remote authenticated users to read arbitrary files, and possibly send HTTP requests to intranet servers or cause a denial of service (CPU and memory consumption), via an XML external entity declaration in conjunction with an entity reference, a different vulnerability than CVE-2011-1757.
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Analysis
by VulDB Data Team • 11/13/2021
The vulnerability identified as CVE-2011-2206 affects DJabberd versions prior to 0.85, specifically within the XMLParser.pm component that processes XML data. This flaw represents a significant security weakness that enables authenticated remote attackers to exploit XML external entity processing mechanisms. The vulnerability stems from insufficient input validation and sanitization of XML documents, allowing maliciously crafted XML content to trigger unintended behavior during parsing operations. The issue manifests when XML documents contain external entity declarations that reference local files or network resources, creating potential attack vectors for information disclosure and service disruption.
The technical exploitation of this vulnerability involves crafting XML content that includes external entity declarations followed by entity references within the XMLParser.pm processing pipeline. When the vulnerable DJabberd server processes such malformed XML input, the parser attempts to resolve the external entities, potentially leading to arbitrary file reads from the server filesystem. This behavior aligns with common XML external entity injection vulnerabilities that have been documented across various platforms and applications. The vulnerability also permits attackers to initiate HTTP requests to internal network resources, effectively enabling internal network reconnaissance and potential lateral movement attacks. Additionally, the processing of malformed XML entities can cause excessive CPU and memory consumption, leading to denial of service conditions that impact legitimate service availability.
From an operational impact perspective, this vulnerability creates multiple attack vectors that can compromise both confidentiality and availability of the affected system. The arbitrary file reading capability allows attackers to access sensitive information stored on the server filesystem, potentially including configuration files, user data, or system credentials. The ability to send HTTP requests to intranet servers opens possibilities for internal network scanning and exploitation of other vulnerable services within the organization's infrastructure. The denial of service component can be particularly damaging as it can exhaust system resources and make the service unavailable to legitimate users, potentially affecting communication services for users relying on the Jabber/XMPP infrastructure.
Security mitigations for this vulnerability should focus on implementing proper XML parsing restrictions and input validation mechanisms. Organizations should immediately upgrade to DJabberd version 0.85 or later, which contains the necessary patches to address this vulnerability. Additional protective measures include configuring XML parsers to disable external entity resolution, implementing strict input validation for all XML content, and establishing network segmentation to limit potential lateral movement. The vulnerability demonstrates the importance of following secure coding practices and adhering to established security guidelines such as those outlined in the CWE database under category CWE-611 for XML external entity processing vulnerabilities. Organizations should also consider implementing intrusion detection systems that can monitor for suspicious XML parsing activities and establish proper access controls to limit the impact of potential exploitation attempts.
This vulnerability type falls under the broader category of XML external entity injection attacks that have been extensively documented in security literature and frameworks such as the MITRE ATT&CK matrix. The attack pattern involves leveraging XML parsing features to access unintended resources, making it a common target for both information gathering and service disruption attacks. The specific nature of this vulnerability highlights the need for comprehensive security testing of XML processing components within applications, particularly those handling user-provided data. Security teams should conduct regular vulnerability assessments and penetration testing to identify similar weaknesses in other XML processing components throughout their infrastructure, as similar patterns have been observed in numerous other applications and systems across different technology stacks.