CVE-2020-1613 in Junos
Summary
by MITRE
A vulnerability in the BGP FlowSpec implementation may cause a Juniper Networks Junos OS device to terminate an established BGP session upon receiving a specific BGP FlowSpec advertisement. The BGP NOTIFICATION message that terminates an established BGP session is sent toward the peer device that originally sent the specific BGP FlowSpec advertisement. This specific BGP FlowSpec advertisement received from a BGP peer might get propagated from a Junos OS device running the fixed release to another device that is vulnerable causing BGP session termination downstream. This issue affects IPv4 and IPv6 BGP FlowSpec deployment. This issue affects Juniper Networks Junos OS: 12.3; 12.3X48 on SRX Series; 14.1X53 on EX and QFX Series; 15.1 versions prior to 15.1R7-S5; 15.1F versions prior to 15.1F6-S13; 15.1X49 versions prior to 15.1X49-D180 on SRX Series; 15.1X53 versions prior to 15.1X53-D238 on QFX5200/QFX5110; 15.1X53 versions prior to 15.1X53-D497 on NFX Series; 15.1X53 versions prior to 15.1X53-D592 on EX2300/EX3400; 16.1 versions prior to 16.1R7-S7; 17.1 versions prior to 17.1R2-S12, 17.1R3; 17.2 versions prior to 17.2R2-S7, 17.2R3; 17.2X75 versions prior to 17.2X75-D102, 17.2X75-D110, 17.2X75-D44; 17.3 versions prior to 17.3R2-S5, 17.3R3-S5; 17.4 versions prior to 17.4R1-S8, 17.4R2; 18.1 versions prior to 18.1R2-S4, 18.1R3; 18.2X75 versions prior to 18.2X75-D20.
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Analysis
by VulDB Data Team • 05/17/2024
This vulnerability represents a critical flaw in the Border Gateway Protocol Flow Specification implementation within Juniper Networks Junos OS devices, classified under CWE-248 as an Unhandled Exception in the BGP subsystem. The vulnerability manifests when a Junos OS device receives a specifically crafted BGP FlowSpec advertisement that triggers an unexpected termination of established BGP sessions. This behavior constitutes a denial-of-service condition that can cascade through network infrastructure, affecting not only the immediate device but potentially downstream systems that receive propagated BGP advertisements. The flaw exists in the protocol handling logic where the system fails to properly validate incoming FlowSpec messages, leading to an abrupt session termination that follows the standard BGP NOTIFICATION message format.
The technical exploitation of this vulnerability occurs through the manipulation of BGP FlowSpec advertisements that contain malformed or unexpected data structures within the FlowSpec NLRI (Network Layer Reachability Information) field. When processed by vulnerable Junos OS versions, these advertisements cause the routing daemon to crash or enter an unstable state, resulting in the immediate termination of the BGP session with the peer that transmitted the malicious advertisement. This behavior follows the BGP protocol specification where NOTIFICATION messages are sent to indicate session termination due to errors, but the vulnerability lies in the fact that the system terminates sessions in response to valid FlowSpec advertisements that should be processed gracefully rather than causing system instability. The issue affects both IPv4 and IPv6 implementations, making it particularly dangerous in modern network environments that utilize dual-stack configurations.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise network stability and availability across entire routing domains. Network operators may experience cascading failures where a single malicious or compromised peer can cause widespread BGP session termination throughout the network infrastructure. The propagation aspect of this vulnerability means that even devices not directly targeted by the malicious advertisement can be affected when the vulnerable Junos OS device forwards the problematic advertisement to other peers. This creates a significant risk for large-scale deployments where BGP sessions are critical for maintaining network connectivity and routing stability, particularly in service provider environments where network availability directly impacts customer service quality and business operations.
Mitigation strategies for this vulnerability should focus on immediate patch deployment across all affected Junos OS versions, with particular attention to the specific release versions mentioned in the advisory. Network administrators should implement BGP session monitoring and alerting systems to detect unusual session termination patterns that may indicate exploitation attempts. The implementation of BGP FlowSpec filtering and validation mechanisms at network boundaries can provide additional protection layers, though these should be considered supplementary rather than primary defenses. Organizations should also establish robust network segmentation strategies to limit the propagation impact of such vulnerabilities. From an ATT&CK perspective, this vulnerability aligns with techniques involving network denial of service and protocol manipulation, and should be addressed through proper network hygiene practices including regular security updates, network monitoring, and incident response procedures. The vulnerability underscores the importance of maintaining current security patches and implementing proper BGP security measures such as BGPsec or route filtering to prevent unauthorized manipulation of routing information.