CVE-2014-3291 in Wireless LAN Controller
Summary
by MITRE
Cisco Wireless LAN Controller (WLC) devices allow remote attackers to cause a denial of service (NULL pointer dereference and device restart) via a zero value in Cisco Discovery Protocol packet data that is not properly handled during SNMP polling, aka Bug ID CSCuo12321.
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Analysis
by VulDB Data Team • 06/20/2021
The vulnerability identified as CVE-2014-3291 affects Cisco Wireless LAN Controller devices, specifically targeting their handling of Cisco Discovery Protocol (CDP) packets during SNMP polling operations. This flaw represents a critical security weakness that can be exploited by remote attackers to disrupt network operations through deliberate denial of service attacks. The vulnerability manifests when the WLC device encounters a zero value within CDP packet data that is not properly validated or handled during the SNMP polling process, leading to a NULL pointer dereference condition that ultimately causes the device to restart automatically.
From a technical perspective, this vulnerability stems from inadequate input validation within the WLC's SNMP polling mechanism. The Cisco Discovery Protocol is a proprietary protocol used by Cisco devices to share information about themselves with neighboring devices, and when malformed CDP packets containing zero values are received, the device fails to properly process these packets. This failure results in a NULL pointer dereference error, which is a common software vulnerability pattern that occurs when a program attempts to access memory through a pointer that has not been properly initialized or has been set to NULL. The improper handling of this specific data condition triggers a system crash that forces the device to reboot, creating a persistent denial of service scenario.
The operational impact of this vulnerability extends beyond simple service disruption as it can severely compromise network availability and reliability for organizations relying on Cisco WLC infrastructure. Network administrators may experience unexpected device restarts that can interrupt wireless connectivity for numerous users, potentially affecting business operations and productivity. The remote exploitability of this vulnerability means that attackers do not need physical access or network credentials to cause disruption, making it particularly dangerous in environments where wireless access is critical. The automatic device restart behavior creates a cascading effect that can be difficult to detect and mitigate, as the system may appear to recover automatically while simultaneously being vulnerable to repeated attacks.
Organizations should implement immediate mitigation strategies including applying Cisco's official security patches and updates that address the specific NULL pointer dereference condition in the SNMP polling handler. Network segmentation and access control measures can help limit the attack surface by restricting which devices can communicate with WLC systems. Monitoring and logging configurations should be enhanced to detect unusual CDP packet patterns or frequent device restarts that may indicate exploitation attempts. According to CWE classification, this vulnerability maps to CWE-476 which describes NULL pointer dereference conditions, while the ATT&CK framework would categorize this under T1499.002 for network denial of service attacks. Additionally, implementing network intrusion detection systems that can identify malformed CDP packets and SNMP polling anomalies provides an additional layer of protection against exploitation attempts. Regular security assessments and vulnerability scanning should be conducted to ensure that all WLC devices remain patched and properly configured to prevent unauthorized exploitation of this and similar vulnerabilities.