CVE-2008-0372 in R3000 Internet Filter
Summary
by MITRE
8e6 R3000 Internet Filter 2.0.05.33, and other versions before 2.0.11, allows remote attackers to bypass intended restrictions via a fragmented HTTP request.
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Analysis
by VulDB Data Team • 12/04/2024
The vulnerability identified as CVE-2008-0372 affects the 8e6 R3000 Internet Filter version 2.0.05.33 and earlier versions, representing a significant security flaw in web content filtering systems. This issue specifically targets the packet fragmentation handling mechanisms within the internet filter software, creating a pathway for malicious actors to circumvent established access controls and content restrictions. The vulnerability exists in the way the system processes fragmented internet protocol packets, particularly when these packets contain http requests that are split across multiple fragments.
The technical flaw stems from improper handling of IP packet fragmentation within the filtering software's network processing stack. When http requests are transmitted as fragmented packets, the filter fails to properly reassemble and inspect the complete request before applying access control policies. This allows attackers to craft malicious http requests where critical portions of the request are placed in separate fragments, enabling them to bypass the content filtering mechanisms that would normally block access to restricted websites or content types. The vulnerability specifically exploits the gap between packet reception and complete request reconstruction, creating a window where filtered content can slip through undetected.
The operational impact of this vulnerability extends beyond simple bypass of content restrictions, potentially enabling more severe security consequences within networks protected by the 8e6 R3000 Internet Filter. Attackers could leverage this flaw to access restricted websites, download malicious content, or establish unauthorized communication channels that would normally be blocked by the filtering system. Organizations relying on this software for network security could experience unauthorized access to sensitive resources, data exfiltration, or compromise of network boundaries, particularly in environments where strict content filtering is essential for regulatory compliance or security policies.
The vulnerability aligns with CWE-129, which addresses improper handling of fragmented data in network applications, and represents a classic example of a protocol-level security weakness that can be exploited through fragment-based attack techniques. From an attack framework perspective, this vulnerability maps to ATT&CK technique T1071.004 for application layer protocol tunneling and T1566 for credential access through social engineering. The issue demonstrates how seemingly benign network protocol handling can create significant security gaps, particularly in filtering systems where the integrity of network traffic inspection is paramount.
Organizations affected by this vulnerability should immediately upgrade to version 2.0.11 or later of the 8e6 R3000 Internet Filter, as this release contains the necessary patches to properly handle fragmented http requests. Network administrators should also implement additional monitoring for unusual traffic patterns that might indicate exploitation attempts, and consider deploying intrusion detection systems that can identify fragmented packet patterns consistent with this attack vector. The fix implemented in the patched version addresses the core issue by ensuring complete packet reassembly occurs before content filtering decisions are made, thereby eliminating the bypass opportunity that existed in earlier versions.