CVE-2015-4275 in ASR 5000
Summary
by MITRE
The Packet Data Network Gateway (aka PGW) component on Cisco ASR 5000 devices with software 18.0.0.59167 and 18.0.0.59211 allows remote attackers to cause a denial of service via a malformed header in a GTPv2 packet, aka Bug ID CSCut11534.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 06/03/2022
The Cisco ASR 5000 series devices operate as critical components in mobile network infrastructures serving as Packet Data Network Gateways that handle signaling and data traffic between mobile networks and external packet data networks. These devices process GTPv2 (GPRS Tunneling Protocol version 2) packets which are essential for managing packet forwarding and session establishment in 4G LTE networks. The vulnerability exists within the processing logic of the PGW component that handles incoming GTPv2 packets, specifically when these packets contain malformed headers that the device cannot properly parse or validate.
The technical flaw manifests in the insufficient input validation mechanisms within the GTPv2 packet processing module of the ASR 5000 software versions 18.0.0.59167 and 18.0.0.59211. When a specially crafted GTPv2 packet with malformed headers reaches the device, the parsing routine fails to properly handle the unexpected data structure, leading to a crash or restart of the affected service. This vulnerability is classified as a buffer over-read or improper input validation issue that falls under CWE-129, which addresses improper validation of array index values. The malformed header structure causes the device to attempt to process data beyond allocated memory boundaries or to interpret invalid data as valid packet components, triggering an unhandled exception that results in system instability.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise network availability and integrity for mobile network operators. A successful exploitation can result in complete denial of service for all users connected through the affected PGW, as the device becomes unavailable to process legitimate traffic. This creates cascading effects throughout the mobile network infrastructure, potentially disrupting emergency services, voice calls, and data connectivity for thousands of users simultaneously. The vulnerability is particularly concerning because it requires no authentication or privileged access, making it a high-severity threat that can be exploited by remote attackers from the internet. Network operators may experience extended downtime while investigating and implementing patches, potentially leading to significant revenue loss and customer dissatisfaction.
Mitigation strategies for this vulnerability require immediate software updates from Cisco to address the malformed header processing issue. Organizations should implement network segmentation to isolate affected devices and monitor for suspicious GTPv2 traffic patterns that might indicate attempted exploitation. The ATT&CK framework categorizes this vulnerability under T1498, which covers Network Denial of Service attacks, and T1071.004, which addresses application layer protocols including GTP. Security teams should also consider implementing intrusion detection systems that can identify malformed GTPv2 packets and automatically block them at network perimeters. Additionally, maintaining comprehensive network monitoring and logging capabilities ensures rapid detection of service disruptions and allows for forensic analysis of attack patterns. Organizations should also review their incident response procedures to ensure quick activation of remediation protocols when similar vulnerabilities are discovered in their network infrastructure.