CVE-2014-2146 in IOS
Summary
by MITRE
The Zone-Based Firewall (ZBFW) functionality in Cisco IOS, possibly 15.4 and earlier, and IOS XE, possibly 3.13 and earlier, mishandles zone checking for existing sessions, which allows remote attackers to bypass intended resource-access restrictions via spoofed traffic that matches one of these sessions, aka Bug IDs CSCun94946 and CSCun96847.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 04/23/2019
The vulnerability identified as CVE-2014-2146 represents a critical flaw in Cisco's Zone-Based Firewall implementation within IOS and IOS XE operating systems. This security weakness specifically targets the zone checking mechanism that governs network traffic flow between different security zones. The vulnerability affects versions 15.4 and earlier for IOS, as well as IOS XE versions 3.13 and earlier, making it a widespread issue across multiple Cisco networking platforms. The flaw stems from improper handling of existing sessions within the zone-based firewall framework, creating a pathway for malicious actors to circumvent established security policies.
The technical exploitation of this vulnerability occurs through a sophisticated spoofing attack that leverages existing network sessions. When a legitimate session exists between network zones, the ZBFW should enforce strict zone-based access controls to prevent unauthorized traffic from traversing between zones. However, the flaw allows attackers to craft spoofed packets that match existing session entries in the firewall's session table. This enables the attacker to bypass the intended zone restrictions by piggybacking on legitimate session state information, effectively creating a tunnel through the firewall's security controls. The vulnerability specifically exploits the session matching logic that occurs during packet inspection, where the firewall incorrectly validates incoming traffic against existing session state rather than enforcing proper zone-based access controls.
The operational impact of CVE-2014-2146 extends far beyond simple network access bypasses, as it fundamentally compromises the security model of Cisco network devices. Attackers can leverage this vulnerability to move laterally within a network, accessing resources that should be restricted to specific security zones. This could enable unauthorized access to sensitive internal systems, potentially leading to data exfiltration, system compromise, or further network infiltration. The vulnerability affects network infrastructure devices that rely on zone-based firewalls for traffic control, making it particularly dangerous in enterprise environments where network segmentation is critical for security. Organizations using affected Cisco IOS and IOS XE versions face significant risk of unauthorized network access, with potential impacts ranging from information disclosure to complete network compromise, depending on the network architecture and security controls in place.
Mitigation strategies for CVE-2014-2146 require immediate attention from network administrators and security teams responsible for Cisco network infrastructure. The primary recommended approach involves applying the relevant security patches and updates provided by Cisco, specifically addressing the zone-based firewall session handling logic. Network administrators should also consider implementing additional monitoring and logging of firewall session activity to detect potential exploitation attempts. The vulnerability aligns with CWE-284, which describes improper access control in software systems, and can be mapped to ATT&CK technique T1071.004 for application layer protocol usage, particularly in the context of network traffic manipulation. Organizations should also review their existing firewall policies and zone configurations to ensure that any potential exploitation attempts are detected through anomaly-based monitoring. Network segmentation strategies should be reinforced, and additional access controls should be implemented to reduce the attack surface. The vulnerability demonstrates the importance of proper session state management in network security devices and highlights the critical need for thorough testing of security control implementations in complex network environments.