CVE-2015-6340 in ASR 5000
Summary
by MITRE
The Proxy Mobile IPv6 (PMIPv6) component in the CDMA implementation on Cisco ASR 5000 devices with software 19.0.M0.60737 allows remote attackers to cause a denial of service (hamgr process restart) via a crafted header in a PMIPv6 packet, aka Bug ID CSCuv63280.
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Analysis
by VulDB Data Team • 06/25/2022
The vulnerability CVE-2015-6340 affects the Proxy Mobile IPv6 implementation within Cisco ASR 5000 series devices running specific software versions. This flaw exists in the CDMA implementation where the device fails to properly validate incoming PMIPv6 packets, creating an exploitable condition that can be leveraged by remote attackers to disrupt service availability. The affected system component specifically targets the hamgr process which is responsible for handling mobility management functions within the mobile network infrastructure. This issue represents a critical weakness in the device's packet processing logic that directly impacts the operational integrity of mobile network services.
The technical flaw manifests through improper input validation of PMIPv6 packet headers, where the system does not adequately sanitize or verify the structure of incoming mobility management messages. When a specially crafted header is transmitted to the device, it triggers an unexpected behavior in the hamgr process that results in automatic restart of this critical system component. This process restart effectively interrupts the mobile network functionality and causes a denial of service condition that affects legitimate mobile users. The vulnerability stems from insufficient bounds checking and header validation mechanisms within the PMIPv6 processing module, allowing malformed data to propagate through the system's validation layers.
The operational impact of this vulnerability extends beyond simple service disruption as it affects the core mobility management functions of mobile networks. When the hamgr process restarts, it creates temporary gaps in mobile connectivity for users within the affected network coverage area, potentially leading to dropped calls, failed data sessions, and overall degradation of service quality. Network operators relying on ASR 5000 devices for CDMA network infrastructure face significant operational challenges when this vulnerability is exploited, as the restart process can take several minutes to complete and may require manual intervention to restore full service functionality. The remote nature of the attack means that adversaries can exploit this vulnerability from outside the network perimeter without requiring physical access or elevated privileges within the device.
Mitigation strategies for CVE-2015-6340 should focus on implementing immediate software updates from Cisco that address the header validation flaw in the PMIPv6 implementation. Network administrators should also consider deploying network access control measures to filter or block suspicious PMIPv6 traffic patterns that could indicate exploitation attempts. The vulnerability aligns with CWE-129 which addresses improper validation of input boundaries, and represents a potential entry point for adversaries following ATT&CK technique T1499.002 for network denial of service attacks. Organizations should also implement monitoring solutions to detect anomalous PMIPv6 packet headers and establish incident response procedures to quickly address any exploitation attempts. Regular security assessments of mobile network infrastructure components are essential to identify similar validation weaknesses that could be exploited in similar network management systems.