CVE-2007-4826 in Quagga
Summary
by MITRE
bgpd in Quagga before 0.99.9 allows explicitly configured BGP peers to cause a denial of service (crash) via a malformed (1) OPEN message or (2) a COMMUNITY attribute, which triggers a NULL pointer dereference. NOTE: vector 2 only exists when debugging is enabled.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 07/27/2019
The vulnerability identified as CVE-2007-4826 affects the bgpd component of Quagga routing software versions prior to 0.99.9, representing a critical denial of service weakness that can be exploited by maliciously configured BGP peers. This flaw exists within the Border Gateway Protocol daemon implementation and specifically targets the handling of malformed network messages that are part of the BGP protocol communication process. The vulnerability stems from insufficient input validation and error handling mechanisms within the bgpd service, creating a scenario where legitimate network traffic can be manipulated to trigger system instability.
The technical exploitation of this vulnerability occurs through two distinct attack vectors that both lead to the same underlying issue of NULL pointer dereference. The first vector involves sending a malformed OPEN message to the affected bgpd service, while the second vector targets a COMMUNITY attribute within BGP messages. The COMMUNITY attribute vector is particularly noteworthy because it only manifests when the debugging functionality is enabled within the Quagga software, indicating that the vulnerability exists in the code path that handles extended BGP attributes but is only triggered under specific operational conditions. Both attack vectors result in the same fundamental problem where the software attempts to access a NULL memory pointer, causing the bgpd process to crash and terminate unexpectedly.
The operational impact of this vulnerability extends beyond simple service disruption, as it can be leveraged by attackers to create persistent denial of service conditions within network infrastructure. When the bgpd daemon crashes, it affects the routing capabilities of the entire network segment that relies on that particular routing daemon for BGP communication, potentially causing widespread network disruption and connectivity issues. The vulnerability is particularly concerning because it can be triggered by remote peers without requiring authentication or elevated privileges, making it a significant threat to network availability. The crash occurs at the application level within the routing software, meaning that even if the underlying operating system remains functional, the BGP routing services become unavailable, affecting network convergence and traffic routing decisions.
Mitigation strategies for this vulnerability should focus on immediate software updates to Quagga versions 0.99.9 or later, where the NULL pointer dereference issues have been addressed through improved input validation and error handling. Network administrators should also consider implementing BGP message filtering and validation mechanisms at network boundaries to prevent malformed messages from reaching vulnerable bgpd instances. The vulnerability aligns with CWE-476 which describes NULL pointer dereference conditions, and it can be categorized under ATT&CK technique T1499.004 for network denial of service attacks. Additional defensive measures include disabling debugging features when not required, as this removes one of the attack vectors, and implementing monitoring systems to detect and alert on bgpd process crashes or restarts that may indicate exploitation attempts. Organizations should also conduct regular vulnerability assessments to identify other potentially affected network devices running older versions of Quagga or similar routing software components.