CVE-2018-0381 in Aironet
Summary
by MITRE
A vulnerability in the Cisco Aironet Series Access Points (APs) software could allow an authenticated, adjacent attacker to cause an affected device to reload unexpectedly, resulting in a denial of service (DoS) condition. The vulnerability is due to a deadlock condition that may occur when an affected AP attempts to dequeue aggregated traffic that is destined to an attacker-controlled wireless client. An attacker who can successfully transition between multiple Service Set Identifiers (SSIDs) hosted on the same AP while replicating the required traffic patterns could trigger the deadlock condition. A watchdog timer that detects the condition will trigger a reload of the device, resulting in a DoS condition while the device restarts.
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Analysis
by VulDB Data Team • 05/30/2023
The vulnerability identified as CVE-2018-0381 affects Cisco Aironet Series Access Points and represents a significant denial of service risk that can be exploited by authenticated adjacent attackers. This flaw resides within the software implementation of wireless access point functionality and specifically targets the traffic handling mechanisms used for managing aggregated wireless client communications. The vulnerability demonstrates the critical importance of proper resource management and synchronization in network infrastructure devices where concurrent operations can lead to system instability.
The technical root cause of this vulnerability stems from a deadlock condition that occurs during traffic dequeuing operations within the access point's wireless processing subsystem. When an affected AP attempts to process aggregated traffic destined for a wireless client controlled by an attacker, the system enters a state where multiple threads or processes become blocked waiting for resources that will never be released. This classic deadlock scenario is particularly dangerous in network infrastructure devices because it can be triggered through legitimate administrative operations while maintaining the appearance of normal network traffic patterns. The vulnerability specifically manifests when an attacker can transition between multiple SSIDs on the same access point, creating the precise traffic conditions necessary to invoke the problematic code path. This requirement for SSID transitions suggests the flaw exists within the shared resource management between different wireless network segments.
The operational impact of this vulnerability extends beyond simple service disruption as it provides attackers with a method to repeatedly cause device reloads through carefully crafted traffic patterns. The watchdog timer mechanism that detects the deadlock condition represents a safety feature that was designed to prevent indefinite system hangs, but in this case it inadvertently provides an attack vector that can be exploited to maintain persistent DoS conditions. During the device reload process, network connectivity is completely disrupted for all wireless clients associated with the affected access point, potentially affecting critical business operations or emergency communications systems that depend on wireless infrastructure. The vulnerability's requirement for adjacent network access means that attackers must be physically present within the wireless coverage area, but this limitation does not diminish the severity of the impact.
Mitigation strategies for CVE-2018-0381 should focus on both immediate defensive measures and long-term architectural improvements. Network administrators should ensure that access point firmware is updated to versions that contain the relevant security patches provided by Cisco, as these updates typically address the underlying race conditions and resource management issues. Network segmentation and proper access controls can help limit the attack surface by restricting unauthorized access to wireless network management interfaces. The implementation of monitoring systems that can detect unusual traffic patterns or frequent device reloads can provide early warning of potential exploitation attempts. From a compliance perspective, this vulnerability aligns with CWE-362 which addresses concurrent execution issues and represents a specific instance of the broader category of deadlock conditions that can be exploited in network infrastructure. Organizations should also consider implementing network access control measures and regular security assessments to identify and remediate similar vulnerabilities that may exist in other network components.
This vulnerability demonstrates the complex nature of wireless network security where legitimate operational requirements can create attack vectors that are difficult to detect and prevent. The fact that the attack requires both authentication and physical proximity limits its scope but does not eliminate the risk, particularly in environments where unauthorized physical access is possible. Security professionals should view this vulnerability as representative of the broader challenge of securing wireless infrastructure, where the need for high availability and performance can create conditions where resource management flaws can be exploited to create denial of service conditions. The attack pattern required to trigger this vulnerability also suggests that similar issues may exist in other wireless network equipment and highlights the importance of comprehensive vulnerability assessment programs that include both automated scanning and manual analysis of network infrastructure components.