CVE-2012-1820 in Quagga
Summary
by MITRE
The bgp_capability_orf function in bgpd in Quagga 0.99.20.1 and earlier allows remote attackers to cause a denial of service (assertion failure and daemon exit) by leveraging a BGP peering relationship and sending a malformed Outbound Route Filtering (ORF) capability TLV in an OPEN message.
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Analysis
by VulDB Data Team • 08/09/2024
The vulnerability identified as CVE-2012-1820 resides within the bgp_capability_orf function of Quagga's bgpd daemon version 0.99.20.1 and earlier. This flaw represents a critical denial of service vulnerability that can be exploited by remote attackers who have established a BGP peering relationship with the targeted system. The vulnerability specifically manifests when the daemon receives a malformed Outbound Route Filtering ORF capability TLV within a BGP OPEN message, leading to an assertion failure that ultimately causes the daemon to terminate unexpectedly. The issue stems from insufficient input validation and error handling within the BGP capability processing logic, creating a scenario where malformed data can trigger a catastrophic failure in the routing daemon.
This vulnerability operates at the network protocol level within the Border Gateway Protocol implementation, making it particularly dangerous in production environments where BGP daemons are critical for network connectivity and routing operations. The attack vector requires only a pre-existing BGP peering relationship, which means that an attacker who has already established communication with the target router can exploit this weakness without requiring additional network access privileges. The malformed ORF capability TLV represents a specific type of BGP capability advertisement that should be properly validated according to RFC 5234 and related BGP specifications. When the bgpd daemon encounters this malformed TLV, the assertion failure occurs because the code does not adequately handle unexpected or malformed capability data structures during the OPEN message processing phase of BGP session establishment.
The operational impact of this vulnerability extends beyond simple service disruption as it can lead to complete routing daemon failure, potentially causing network partitions and routing instability across the affected infrastructure. When the bgpd daemon exits due to the assertion failure, all BGP sessions managed by that daemon are terminated, which can result in significant network outages as routing information becomes unavailable. Network administrators may experience cascading failures as other routing protocols attempt to adapt to the sudden loss of BGP connectivity, potentially triggering broader network instability. The vulnerability's classification aligns with CWE-691, which addresses Insufficient Control Flow Management, as the daemon fails to properly control the execution flow when encountering malformed input. Additionally, this vulnerability maps to ATT&CK technique T1499.004, which involves network disruption through manipulation of network protocols, specifically targeting the availability aspect of the network infrastructure.
Mitigation strategies for CVE-2012-1820 should focus on immediate patching of affected Quagga installations to version 0.99.20.2 or later, which contains the necessary fixes for proper input validation of BGP capability TLVs. Network administrators should also implement additional monitoring and alerting mechanisms to detect unusual BGP OPEN message patterns that might indicate exploitation attempts. Configuration changes such as disabling ORF capability processing or implementing stricter BGP session validation can serve as temporary workarounds while patches are deployed. The fix implemented by Quagga developers involved strengthening the input validation logic within the bgp_capability_orf function to properly handle malformed capability TLVs and prevent assertion failures. Organizations should also conduct comprehensive vulnerability assessments of their BGP infrastructure to identify any other potential weaknesses in their routing protocol implementations that could be exploited in similar manners.