CVE-2018-17539 in ZebOS
Summary
by MITRE
The BGP daemon (bgpd) in all IP Infusion ZebOS versions to 7.10.6 and all OcNOS versions to 1.3.3.145 allow remote attackers to cause a denial of service attack via an autonomous system (AS) path containing 8 or more autonomous system number (ASN) elements.
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Analysis
by VulDB Data Team • 06/22/2023
The vulnerability identified as CVE-2018-17539 affects the Border Gateway Protocol daemon within IP Infusion ZebOS and OcNOS networking operating systems, representing a critical denial of service weakness that impacts network infrastructure reliability. This flaw specifically manifests in the bgpd component responsible for managing BGP routing decisions between autonomous systems, making it a significant concern for network operators who depend on stable routing protocols for their infrastructure. The vulnerability exists in all versions of ZebOS up to 7.10.6 and OcNOS up to 1.3.3.145, indicating a widespread exposure across multiple networking platforms from the same vendor.
The technical mechanism underlying this vulnerability involves the improper handling of autonomous system path attributes within BGP update messages. When a remote attacker crafts a BGP update containing an AS path with eight or more autonomous system numbers, the bgpd daemon fails to process this malformed input correctly, leading to a crash or restart of the routing daemon. This behavior stems from insufficient validation and bounds checking within the BGP path processing logic, where the system does not adequately verify the length of AS path sequences before attempting to parse or store the information. The flaw essentially creates a buffer overflow condition or memory corruption scenario when processing extended path information, causing the daemon to terminate unexpectedly and disrupt routing operations.
The operational impact of this vulnerability extends far beyond simple service disruption, as it can compromise the stability and availability of entire network domains. When the bgpd daemon crashes due to this vulnerability, it results in immediate loss of routing information between autonomous systems, potentially causing routing black holes where traffic cannot be properly directed through the network. Network operators may experience cascading failures as routing tables become inconsistent across different network segments, leading to widespread connectivity issues that can affect multiple services and customers. The remote nature of the attack means that adversaries can exploit this weakness from outside the network perimeter without requiring local access or authentication credentials, making it particularly dangerous for internet-facing network infrastructure.
Network security professionals should consider this vulnerability in the context of the MITRE ATT&CK framework, where it aligns with techniques involving service disruption and denial of service attacks. The vulnerability also maps to CWE-129, which describes improper validation of the length of input data, and CWE-125, which covers out-of-bounds read conditions that can lead to system instability. Organizations should implement immediate mitigations including network segmentation to isolate vulnerable devices, implementing BGP path validation mechanisms, and deploying rate limiting or filtering to prevent malformed BGP updates from reaching affected systems. The most effective long-term solution involves applying vendor-provided security patches and updates to bring systems to versions that properly validate AS path lengths and implement robust input sanitization techniques to prevent similar buffer overflow conditions in future. Additionally, monitoring systems should be configured to detect unusual BGP update patterns and alert administrators to potential exploitation attempts.
The broader implications of this vulnerability highlight the critical importance of input validation in network protocol implementations, particularly for routing daemons that handle critical infrastructure data. This flaw demonstrates how seemingly simple protocol attributes like AS path lengths can become attack vectors when proper bounds checking is not implemented, emphasizing the need for comprehensive security testing of network infrastructure software. The vulnerability also underscores the necessity of maintaining up-to-date security patches and implementing defense-in-depth strategies that include network monitoring, access controls, and regular security assessments to protect against similar weaknesses in other network components.