CVE-2017-12222 in IOS XE
Summary
by MITRE
A vulnerability in the wireless controller manager of Cisco IOS XE could allow an unauthenticated, adjacent attacker to cause a restart of the switch and result in a denial of service (DoS) condition. The vulnerability is due to insufficient input validation. An attacker could exploit this vulnerability by submitting a crafted association request. An exploit could allow the attacker to cause the switch to restart. This vulnerability affects Cisco Catalyst 3650 and 3850 switches running IOS XE Software versions 16.1 through 16.3.3, and acting as wireless LAN controllers (WLC). Cisco Bug IDs: CSCvd45069.
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Analysis
by VulDB Data Team • 01/14/2021
The vulnerability identified as CVE-2017-12222 represents a critical denial of service weakness within Cisco IOS XE software that specifically impacts wireless controller functionality on certain Catalyst switch models. This flaw exists within the wireless controller manager component of the operating system, creating a pathway for unauthenticated attackers who are physically adjacent to the affected network equipment to disrupt service availability. The vulnerability stems from inadequate input validation mechanisms that fail to properly sanitize or verify association requests submitted to the wireless controller. Attackers can exploit this weakness by crafting and transmitting specially formatted association requests that trigger an abnormal system state leading to complete device restart. The affected hardware includes Cisco Catalyst 3650 and 3850 series switches when configured to function as wireless LAN controllers, specifically within IOS XE software versions ranging from 16.1 through 16.3.3. This represents a significant operational risk as the vulnerability allows for remote service disruption without requiring authentication credentials or network access beyond physical proximity to the target device.
The technical exploitation of this vulnerability aligns with common software security principles and demonstrates a classic input validation failure pattern that can be categorized under CWE-20, which addresses improper input validation. The flaw operates at the network protocol level where wireless association requests are processed, making it particularly dangerous as it targets the fundamental communication mechanisms used by wireless clients to connect to access points. The attacker's ability to cause a complete device restart through a single crafted association request indicates a severe lack of defensive programming practices within the wireless controller manager module. This type of vulnerability is particularly concerning because it can be exploited by attackers with minimal technical expertise and requires only physical proximity to the target equipment, making it accessible to both malicious insiders and external threat actors who can gain access to the physical network environment. The impact extends beyond simple service interruption as the restart process can result in temporary loss of wireless network connectivity for all connected clients, potentially affecting business operations and network availability.
From an operational perspective, this vulnerability creates substantial risk for organizations relying on Cisco Catalyst switches configured as wireless LAN controllers, particularly in environments where physical security controls may be inadequate or where unauthorized physical access to network equipment cannot be guaranteed. The DoS condition caused by the vulnerability can persist until manual intervention occurs or until the device automatically recovers from the restart state, which may not occur immediately. Network administrators face the challenge of maintaining service availability while addressing this vulnerability, as the workaround typically involves either disabling wireless functionality or implementing physical access controls that may not be feasible in all environments. The vulnerability affects multiple software versions within the 16.1 to 16.3.3 range, indicating a prolonged period during which the flaw existed without adequate protection mechanisms. Organizations must also consider the potential for this vulnerability to be leveraged as part of broader attack campaigns, where attackers might use the DoS capability to create distractions while conducting other malicious activities.
Mitigation strategies for CVE-2017-12222 should prioritize immediate software updates to the affected IOS XE versions, with Cisco releasing patches specifically addressing the input validation issues within the wireless controller manager. Network administrators should implement physical security measures to prevent unauthorized access to network equipment, including secure network closets and restricted access controls. The implementation of network access control lists and wireless management protocols that can filter or validate association requests may provide additional layers of protection. Organizations should also consider monitoring wireless network traffic for unusual association request patterns that could indicate exploitation attempts. The vulnerability's classification under ATT&CK technique T1499.004 for network denial of service indicates that this weakness fits within broader adversary tactics for service disruption. Additionally, the remediation process should include comprehensive testing of updated firmware to ensure that the patch does not introduce compatibility issues with existing network configurations. Regular vulnerability assessments and network segmentation strategies can help reduce the attack surface and limit the potential impact of similar vulnerabilities in the future. The incident underscores the importance of maintaining current software versions and implementing robust network security practices that address both logical and physical security considerations.