CVE-2009-1572 in Quagga
Summary
by MITRE
The BGP daemon (bgpd) in Quagga 0.99.11 and earlier allows remote attackers to cause a denial of service (crash) via an AS path containing ASN elements whose string representation is longer than expected, which triggers an assert error.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 01/05/2025
The vulnerability identified as CVE-2009-1572 affects the Border Gateway Protocol daemon within Quagga routing software version 0.99.11 and earlier releases. This issue represents a classic buffer overflow condition that manifests through improper input validation during BGP route processing. The flaw occurs when the bgpd process encounters an Autonomous System Path attribute containing ASN elements with unexpectedly long string representations, leading to a critical assertion failure that terminates the daemon process. This vulnerability directly impacts network infrastructure stability as BGP daemons serve as critical components in internet routing operations, making them prime targets for denial of service attacks that can disrupt internet connectivity for affected networks.
The technical implementation of this vulnerability stems from insufficient validation of AS path attributes during BGP message parsing. When processing incoming BGP updates, the bgpd daemon performs assertions to verify the integrity of ASN elements within the AS path. However, the code does not properly handle cases where ASN string representations exceed predetermined length limits, causing the assertion checks to fail and resulting in immediate process termination. This behavior aligns with CWE-129, which describes improper validation of input lengths, and CWE-682, which covers incorrect arithmetic operations that can lead to assertion failures. The vulnerability operates at the network protocol level within the BGP implementation, specifically targeting the path attribute validation logic that ensures routing information integrity.
The operational impact of CVE-2009-1572 extends beyond simple service disruption to potentially compromise entire routing domains. Network operators relying on affected Quagga versions face significant risks as a single malicious BGP update containing crafted AS path attributes can cause immediate daemon crashes, leading to routing table inconsistencies and potential blackholing of traffic. This vulnerability can be exploited remotely without authentication requirements, making it particularly dangerous in production environments where BGP peering relationships are established with external partners. The attack vector aligns with ATT&CK technique T1498.001, which covers network denial of service attacks, and represents a significant threat to network resilience and availability. Organizations may experience cascading failures as routing disruptions propagate through interconnected networks, potentially affecting multiple autonomous systems simultaneously.
Mitigation strategies for this vulnerability require immediate patching of affected Quagga installations to version 0.99.12 or later, which contains the necessary fixes for proper AS path validation. Network administrators should implement BGP route filtering and validation mechanisms to prevent malformed updates from reaching vulnerable daemons, utilizing techniques such as prefix lists and AS path access control lists. Additionally, implementing monitoring solutions that can detect abnormal BGP update patterns and daemon restarts provides early warning capabilities for potential exploitation attempts. The fix addresses the core validation issue by implementing proper bounds checking on ASN string representations and ensuring that assertion failures do not result in process termination. Organizations should also consider implementing redundant routing daemons and failover mechanisms to maintain network availability during patch deployment and to minimize the impact of potential exploitation attempts.