CVE-2015-6351 in ASR 5000
Summary
by MITRE
Cisco ASR 5500 System Architecture Evolution (SAE) Gateway devices with software 19.1.0.61559 and 19.2.0 allow remote attackers to cause a denial of service (BGP process restart) via a crafted header in a BGP packet, aka Bug ID CSCuw65781.
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Analysis
by VulDB Data Team • 06/25/2022
The vulnerability identified as CVE-2015-6351 affects Cisco ASR 5500 System Architecture Evolution gateway devices operating with specific software versions 19.1.0.61559 and 19.2.0. This represents a critical denial of service flaw that can be exploited remotely through manipulation of Border Gateway Protocol packets. The affected devices are part of Cisco's core routing infrastructure, specifically designed for high-performance network services including mobile backhaul and enterprise connectivity. These systems serve as critical components in large-scale telecommunications networks where uninterrupted operation is essential for maintaining service availability.
The technical flaw resides in the BGP packet processing implementation within the affected Cisco software versions. Attackers can craft malicious BGP packets containing specially formatted headers that trigger unexpected behavior in the BGP process handling mechanism. When the vulnerable device receives these crafted packets, the BGP process undergoes an automatic restart, effectively disrupting routing operations and causing temporary network outages. This vulnerability falls under the CWE-121 category of stack-based buffer overflow, though the specific manifestation involves process restart rather than traditional memory corruption. The flaw exploits the lack of proper input validation during BGP packet header parsing, allowing malformed data to propagate through the system's routing protocols.
The operational impact of this vulnerability extends beyond simple service disruption, as it affects critical network infrastructure components that may be part of core telecommunications networks. When the BGP process restarts, routing tables become temporarily unavailable, causing network traffic to be rerouted or dropped entirely. This can result in significant service degradation for end users, particularly in mobile backhaul networks where the ASR 5500 devices are commonly deployed. The remote exploit capability means that attackers can trigger the denial of service from outside the network perimeter without requiring physical access or authentication credentials. Network administrators may experience extended downtime while troubleshooting and implementing remediation measures, potentially affecting multiple services simultaneously across interconnected network segments.
Mitigation strategies for this vulnerability include immediate software patching to address the BGP packet processing flaw in affected Cisco devices. Organizations should prioritize updating their ASR 5500 systems to versions that contain the security fix for Bug ID CSCuw65781, which typically involves enhanced input validation for BGP packet headers. Network segmentation and access control measures can provide additional defense-in-depth by limiting exposure of vulnerable devices to untrusted network segments. Implementing BGP monitoring and anomaly detection systems can help identify suspicious packet patterns that may indicate exploitation attempts. The ATT&CK framework categorizes this vulnerability under the T1499.004 technique for network denial of service, emphasizing the importance of proper input validation and process resilience in network infrastructure components. Organizations should also consider implementing rate limiting for BGP updates and configuring logging mechanisms to detect potential exploitation attempts, ensuring comprehensive protection against similar vulnerabilities in network routing protocols.