CVE-2014-3409 in IOS
Summary
by MITRE
The Ethernet Connectivity Fault Management (CFM) handling feature in Cisco IOS 12.2(33)SRE9a and earlier and IOS XE 3.13S and earlier allows remote attackers to cause a denial of service (device reload) via malformed CFM packets, aka Bug ID CSCuq93406.
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Analysis
by VulDB Data Team • 02/23/2022
The vulnerability described in CVE-2014-3409 represents a critical denial of service flaw within Cisco IOS and IOS XE operating systems that affects the Ethernet Connectivity Fault Management protocol implementation. This vulnerability specifically targets the CFM handling functionality that is used to monitor and maintain connectivity in Ethernet networks, particularly in service provider and enterprise environments where network reliability is paramount. The flaw exists in versions of Cisco IOS 12.2(33)SRE9a and earlier, as well as IOS XE 3.13S and earlier releases, making it a widespread issue across multiple Cisco network device families including routers and switches that implement CFM for network monitoring purposes. The vulnerability was documented under Bug ID CSCuq93406 and represents a significant security concern for organizations relying on Cisco networking equipment for critical infrastructure operations.
The technical implementation flaw occurs when the affected Cisco IOS and IOS XE systems process malformed CFM packets that contain specially crafted data structures or invalid packet formats. These malformed packets exploit a buffer handling or parsing vulnerability within the CFM protocol stack, causing the device to crash and subsequently reload its operating system. The vulnerability stems from insufficient input validation and error handling within the CFM processing code, which fails to properly sanitize incoming packets before attempting to parse their contents. When an attacker sends carefully constructed CFM packets to a vulnerable device, the system's failure handling mechanism triggers an unexpected system restart, resulting in complete service interruption for the affected network infrastructure. This type of vulnerability falls under the CWE-129 weakness category, which deals with insufficient validation of the length or size of input data, and is classified as a remote code execution vulnerability that can be exploited without authentication.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise network stability and availability for organizations relying on Cisco networking equipment. Network administrators may experience unexpected device reloads that can occur at any time without warning, leading to service interruptions that can affect business operations, customer connectivity, and overall network reliability. The remote nature of the attack means that adversaries can exploit this vulnerability from outside the network perimeter, making it particularly dangerous for service providers and organizations with exposed network devices. The vulnerability can be exploited by attackers who have network access to send malformed packets to target devices, potentially causing cascading failures if multiple devices in a network are affected simultaneously. According to ATT&CK framework, this vulnerability aligns with the T1499.004 technique for network denial of service, where adversaries leverage network protocols to disrupt services and cause system failures.
Organizations affected by this vulnerability should immediately implement mitigations including applying the latest security patches and updates provided by Cisco, which address the underlying buffer handling issues in the CFM implementation. Network segmentation and access control measures should be implemented to limit exposure of vulnerable devices to untrusted networks, while monitoring systems should be configured to detect unusual device reload patterns that might indicate exploitation attempts. Device administrators should also consider disabling CFM functionality on devices where it is not required, as a temporary workaround while permanent patches are deployed. Network traffic filtering rules can be implemented to drop malformed CFM packets at network boundaries, preventing exploitation attempts from reaching vulnerable devices. The vulnerability demonstrates the importance of proper input validation and error handling in network protocol implementations, as highlighted by industry standards that emphasize the need for robust security measures in network infrastructure software to prevent similar issues from occurring in future deployments.