CVE-2015-0657 in IOS XR
Summary
by MITRE
Cisco IOS XR allows remote attackers to cause a denial of service (RSVP process reload) via a malformed RSVP packet, aka Bug ID CSCur69192.
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Analysis
by VulDB Data Team • 06/22/2017
The vulnerability identified as CVE-2015-0657 affects Cisco IOS XR networking software, specifically targeting the Resource Reservation Protocol (RSVP) implementation within the routing and switching infrastructure. This flaw represents a critical denial of service weakness that can be exploited by remote attackers without authentication, making it particularly dangerous in production network environments where continuous availability is paramount. The vulnerability manifests when the RSVP process within IOS XR encounters malformed packets that it cannot properly handle, leading to unexpected process reloads that disrupt network operations.
The technical root cause of this vulnerability lies in insufficient input validation within the RSVP packet processing module of Cisco IOS XR. When malformed RSVP packets are received, the system fails to properly sanitize or reject these invalid inputs, causing the RSVP process to crash and subsequently reload. This process reload effectively disrupts the network's ability to maintain proper resource reservations and traffic engineering capabilities, which are fundamental to quality of service management in carrier-grade networks. The flaw demonstrates poor error handling practices and inadequate defensive programming measures that are commonly associated with buffer overflow vulnerabilities and input validation failures.
From an operational perspective, the impact of CVE-2015-0657 extends beyond simple service disruption to potentially compromise network stability and reliability. In large-scale deployments, such as those found in telecommunications carriers or enterprise backbone networks, the automatic reload of the RSVP process can cause cascading failures affecting multiple network segments. The vulnerability affects Cisco IOS XR software versions prior to 5.2.4, 5.3.4, and 5.4.1, making it particularly concerning for organizations maintaining legacy network infrastructure. Network administrators may experience unexpected outages in traffic engineering services, leading to degraded performance for applications that depend on RSVP-based QoS mechanisms.
The vulnerability aligns with CWE-20, which describes improper input validation as a fundamental weakness in software security design. This weakness allows attackers to manipulate system behavior through crafted inputs, leading to various security consequences including denial of service. From an ATT&CK framework perspective, this vulnerability maps to the T1499.004 technique for network denial of service, where adversaries exploit weaknesses in network protocols to disrupt service availability. The remote exploitability without authentication makes it particularly attractive to threat actors seeking to cause disruption or gain access to network resources through service degradation.
Mitigation strategies for CVE-2015-0657 primarily involve applying the official Cisco security patches and updates that address the input validation issues within the RSVP processing module. Organizations should prioritize upgrading their IOS XR software to versions 5.2.4, 5.3.4, or 5.4.1, depending on their current deployment. Network administrators should also implement network segmentation and access controls to limit exposure, while monitoring for suspicious RSVP traffic patterns that might indicate exploitation attempts. Additional defensive measures include implementing rate limiting for RSVP packets and configuring automatic failover mechanisms to minimize service disruption during potential exploitation events. The vulnerability serves as a reminder of the critical importance of maintaining up-to-date network infrastructure and implementing robust input validation controls in network protocol implementations.