CVE-2016-1436 in ASR 5000
Summary
by MITRE
The General Packet Radio Switching Tunneling Protocol 1 (aka GTPv1) implementation on Cisco ASR 5000 Packet Data Network Gateway devices before 19.4 allows remote attackers to cause a denial of service (Session Manager process restart) via a crafted GTPv1 packet, aka Bug ID CSCuz46198.
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Analysis
by VulDB Data Team • 08/24/2022
The vulnerability CVE-2016-1436 represents a critical denial of service flaw within the GTPv1 implementation of Cisco ASR 5000 Packet Data Network Gateway devices. This issue affects versions prior to 19.4 and specifically targets the Session Manager process responsible for handling GTPv1 tunneling operations. The vulnerability manifests when the system receives a malformed or crafted GTPv1 packet that triggers an unexpected behavior in the processing logic, ultimately leading to a complete restart of the Session Manager process. This type of vulnerability falls under the category of software defects that can be exploited remotely without requiring authentication, making it particularly dangerous in production environments where network availability is paramount.
The technical flaw stems from inadequate input validation within the GTPv1 packet processing module of the Cisco ASR 5000 platform. When a specially crafted GTPv1 packet is received, the system fails to properly handle the malformed packet structure, causing the Session Manager process to crash and restart automatically. This process restart disrupts ongoing GTPv1 tunneling operations and can result in temporary loss of service for mobile network subscribers connected through the affected gateway. The vulnerability is classified as CWE-129, representing an input validation issue where insufficient checks are performed on received data before processing, and aligns with ATT&CK technique T1499.1 for network denial of service attacks. The GTPv1 protocol is fundamental to 3G and 4G mobile networks, used for creating and managing tunnels between network elements, making this vulnerability particularly impactful for mobile operators.
The operational impact of CVE-2016-1436 extends beyond simple service disruption to potentially affecting network reliability and subscriber experience. When the Session Manager process restarts, it can cause temporary disconnections for mobile users, leading to dropped calls, interrupted data sessions, and degraded network performance. Mobile network operators relying on Cisco ASR 5000 devices for their core network infrastructure face significant risk of service degradation, especially during peak usage periods when the system is under heavy load. The vulnerability's remote exploitability means that attackers can trigger the denial of service condition from external network positions without requiring physical access or network credentials, making it an attractive target for malicious actors seeking to disrupt mobile services. This type of attack can be particularly damaging for operators providing critical communication services and can result in financial losses due to service interruptions and potential customer complaints.
Mitigation strategies for CVE-2016-1436 primarily involve applying the vendor-supplied software updates and patches that address the input validation flaw in the GTPv1 processing module. Cisco released version 19.4 and subsequent releases that contain fixes for this vulnerability, including enhanced packet validation routines and improved error handling mechanisms. Network administrators should also implement network monitoring solutions to detect anomalous GTPv1 traffic patterns that may indicate exploitation attempts, and establish network segmentation strategies to limit the potential impact of such attacks. Additional defensive measures include configuring access control lists to filter suspicious GTPv1 packets at network boundaries and implementing rate limiting mechanisms to prevent flooding attacks. The vulnerability demonstrates the importance of maintaining up-to-date network infrastructure and highlights the need for robust input validation in network protocol implementations. Organizations should also consider implementing intrusion detection systems specifically tuned to detect GTPv1-related attack patterns and establish incident response procedures for handling such denial of service events.