CVE-2016-1367 in ASA
Summary
by MITRE
The DHCPv6 relay implementation in Cisco Adaptive Security Appliance (ASA) Software 9.4.1 allows remote attackers to cause a denial of service (device reload) via crafted DHCPv6 packets, aka Bug ID CSCus23248.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 10/15/2024
The vulnerability described in CVE-2016-1367 represents a critical denial of service flaw within Cisco Adaptive Security Appliance software version 9.4.1. This issue specifically affects the DHCPv6 relay functionality, which serves as a crucial network infrastructure component for managing IPv6 address allocation and network configuration. The DHCPv6 relay process acts as an intermediary between IPv6 clients and servers, forwarding DHCPv6 messages across network segments. When improperly handling crafted packets, the ASA software fails to maintain stable operation, leading to complete device reloads that disrupt network services.
The technical root cause of this vulnerability lies in inadequate input validation within the DHCPv6 relay implementation. Attackers can exploit this weakness by sending maliciously constructed DHCPv6 packets that trigger buffer overflows or memory corruption within the ASA software's processing routines. The flaw specifically manifests when the device receives malformed DHCPv6 relay messages that exceed expected parameter boundaries or contain unexpected field values. This vulnerability maps to CWE-121, which describes stack-based buffer overflow conditions, and CWE-122, which covers heap-based buffer overflow scenarios. The improper handling of these packets causes the ASA to enter an unstable state where memory management routines fail, ultimately resulting in system crashes and automatic device reloads.
The operational impact of this vulnerability extends beyond simple service disruption to encompass broader network reliability concerns. Network administrators face the risk of unexpected outages that can affect critical infrastructure services, particularly in environments where ASA appliances serve as primary network gateways or security boundaries. The remote nature of the attack means that adversaries can exploit this vulnerability from outside the network perimeter, making it particularly dangerous for organizations with exposed ASA appliances. This vulnerability also aligns with ATT&CK technique T1499.004, which covers network disruption through resource exhaustion, and represents a significant threat to availability in the CIA triad. Organizations relying on ASA appliances for network security may experience cascading failures as the device reloads, potentially affecting multiple network services simultaneously.
Mitigation strategies for CVE-2016-1367 involve multiple layers of defensive measures. Cisco released software patches and updates addressing the specific buffer handling issues within the DHCPv6 relay implementation, which should be deployed immediately across affected ASA installations. Network administrators should implement access control lists to restrict DHCPv6 traffic to trusted sources only, limiting the attack surface available to potential adversaries. Additionally, monitoring systems should be configured to detect unusual patterns of DHCPv6 traffic that may indicate exploitation attempts. The implementation of network segmentation can help contain the impact of successful attacks, preventing lateral movement within the network. Organizations should also consider disabling DHCPv6 relay functionality entirely if the service is not required, following the principle of least privilege. Regular security assessments and vulnerability scanning should be conducted to identify any remaining instances of the vulnerable software version, ensuring comprehensive protection against this and similar threats.