CVE-2011-3324 in Quagga
Summary
by MITRE
The ospf6_lsa_is_changed function in ospf6_lsa.c in the OSPFv3 implementation in ospf6d in Quagga before 0.99.19 allows remote attackers to cause a denial of service (assertion failure and daemon exit) via trailing zero values in the Link State Advertisement (LSA) header list of an IPv6 Database Description message.
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Analysis
by VulDB Data Team • 12/23/2024
The vulnerability identified as CVE-2011-3324 represents a critical flaw in the OSPFv3 routing protocol implementation within the Quagga routing daemon software. This issue specifically affects the ospf6_lsa_is_changed function located in the ospf6_lsa.c file, which is responsible for processing Link State Advertisement (LSA) headers within OSPFv3 messages. The vulnerability manifests when the OSPFv3 daemon receives IPv6 Database Description messages containing trailing zero values in the LSA header list, leading to an assertion failure that ultimately causes the daemon to terminate unexpectedly. This type of vulnerability falls under the category of software defects that can be exploited to disrupt network services through denial of service attacks.
The technical flaw stems from inadequate input validation within the OSPFv3 implementation's LSA processing logic. When the ospf6_lsa_is_changed function encounters trailing zero values in the LSA header list of an IPv6 Database Description message, it fails to properly handle these malformed inputs, resulting in an assertion failure. This assertion failure occurs because the function does not adequately validate the structure and content of incoming LSA headers, particularly when they contain unexpected trailing zero bytes. The vulnerability is classified as a buffer over-read or improper input validation issue that can be leveraged by remote attackers to trigger the daemon's termination. This flaw directly relates to CWE-129, which addresses improper validation of length of inputs, and CWE-691, which covers insufficient control of a resource through a public interface.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise network stability and availability. When the ospf6d daemon crashes due to this assertion failure, it creates a significant disruption in IPv6 routing operations within networks that rely on Quagga's OSPFv3 implementation. Network administrators may experience routing instability, as the daemon's termination can cause routing table inconsistencies and potential black holes in IPv6 network traffic. The remote nature of the attack means that any system with access to the OSPFv3 network can exploit this vulnerability without requiring local privileges, making it particularly dangerous in network environments where OSPFv3 is actively used. This vulnerability also aligns with ATT&CK technique T1499.004, which covers network disruption through denial of service attacks targeting network infrastructure components.
Mitigation strategies for this vulnerability require immediate patching of Quagga installations to version 0.99.19 or later, which contains the necessary fixes for the LSA header processing logic. Network administrators should also implement monitoring solutions to detect unusual OSPFv3 traffic patterns that might indicate exploitation attempts. Additional protective measures include configuring access controls to limit OSPFv3 message exchanges to trusted network segments only, implementing network segmentation to isolate critical routing components, and maintaining robust backup routing configurations that can be quickly activated in case of daemon failures. Organizations should also consider implementing intrusion detection systems that can identify malformed OSPFv3 messages containing trailing zero values in LSA headers. The fix implemented in Quagga 0.99.19 specifically addresses the assertion failure by adding proper input validation checks for LSA header structures, ensuring that trailing zero values are handled gracefully rather than causing daemon termination.