CVE-2004-2283 in DansGuardian
Summary
by MITRE
Unknown vulnerability in DansGuardian before 2.6.1-13 allows remote attackers to bypass URL filters via a crafted request that causes a page to be added to the clean page cache.
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Analysis
by VulDB Data Team • 06/25/2018
The vulnerability identified as CVE-2004-2283 represents a significant security flaw in DansGuardian, a widely deployed web content filtering proxy software that has been instrumental in organizational network security policies since its initial release in 2002. This particular vulnerability affects versions prior to 2.6.1-13 and stems from a fundamental design weakness in how the software handles URL filtering mechanisms, specifically within its caching subsystem. The issue manifests when remote attackers craft specially designed HTTP requests that exploit a logic flaw in the content filtering process, allowing malicious content to circumvent established security controls.
The technical implementation of this vulnerability resides in the interaction between DansGuardian's URL filtering engine and its clean page caching mechanism. When a crafted HTTP request is processed, the software incorrectly handles the caching logic for filtered content, resulting in a scenario where pages that should have been blocked or filtered are instead cached as legitimate content. This misconfiguration allows attackers to bypass security controls by leveraging the cached content to access otherwise restricted web resources. The flaw operates at the application layer and requires minimal privileges to exploit, making it particularly dangerous in enterprise environments where DansGuardian is deployed to protect against malicious web content.
The operational impact of this vulnerability extends beyond simple bypass of content filters, creating potential pathways for advanced persistent threats to establish footholds within secured networks. When attackers successfully exploit this vulnerability, they can access blocked websites, download malicious content, or establish command and control channels through previously filtered resources. The implications are particularly severe in educational institutions, corporate environments, and government agencies that rely on DansGuardian for network protection, as this vulnerability essentially undermines the entire security posture established by the content filtering system. The cached nature of the bypassed content also means that multiple users can be affected simultaneously, amplifying the potential damage within a network environment.
The vulnerability aligns with CWE-20, which describes improper input validation, and demonstrates characteristics consistent with the ATT&CK technique T1566, specifically the use of malicious content to bypass security controls. Organizations implementing DansGuardian should prioritize immediate patching to version 2.6.1-13 or later, as this represents the first official release that addresses the caching logic flaw. Additional mitigations include implementing network segmentation, deploying intrusion detection systems to monitor for suspicious HTTP request patterns, and conducting regular security audits of proxy configurations. Security teams should also consider implementing additional layers of content filtering and monitoring solutions to provide defense-in-depth against similar vulnerabilities that may exist in other network security tools. The incident underscores the critical importance of maintaining up-to-date security software and the potential consequences of operating legacy versions of network security infrastructure.