CVE-2019-1796 in Wireless LAN Controller
Summary
by MITRE
A vulnerability in the handling of Inter-Access Point Protocol (IAPP) messages by Cisco Wireless LAN Controller (WLC) Software could allow an unauthenticated, adjacent attacker to cause a denial of service (DoS) condition. The vulnerability exist because the software improperly validates input on fields within IAPP messages. An attacker could exploit the vulnerability by sending malicious IAPP messages to an affected device. A successful exploit could allow the attacker to cause the Cisco WLC Software to reload, resulting in a DoS condition. Software versions prior to 8.2.170.0, 8.5.150.0, and 8.8.100.0 are affected.
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Analysis
by VulDB Data Team • 09/04/2023
The vulnerability identified as CVE-2019-1796 represents a critical denial of service weakness within Cisco Wireless LAN Controller software that specifically targets the Inter-Access Point Protocol message processing mechanisms. This flaw exists in the fundamental handling of network communication protocols that enable wireless access points to coordinate with each other and with the central wireless controller. The vulnerability stems from insufficient input validation procedures that fail to properly sanitize or verify the integrity of data fields contained within IAPP messages, creating an exploitable entry point for malicious actors positioned within the same network segment. The security implications are particularly concerning given that the attack requires only adjacent network access and does not demand authentication credentials, making it accessible to attackers who have physical or network proximity to the targeted wireless infrastructure.
The technical exploitation of this vulnerability occurs through the deliberate crafting and transmission of malformed IAPP messages that specifically target the input validation gaps within the Cisco WLC software stack. When the affected software receives these maliciously constructed messages, the improper validation of fields within the protocol payload causes the system to enter an unstable state that ultimately results in an automatic system reload or reboot cycle. This behavior constitutes a classic denial of service attack pattern where the legitimate operation of the wireless network infrastructure is disrupted through the intentional destabilization of the control plane components. The vulnerability affects multiple software version streams including those prior to 8.2.170.0, 8.5.150.0, and 8.8.100.0, indicating that this represents a long-standing issue within the Cisco wireless controller software lineage that required multiple version-specific patches to address properly.
From an operational perspective, the impact of CVE-2019-1796 extends beyond simple service disruption to potentially compromise the entire wireless network infrastructure that relies on the affected Cisco WLC devices. The automatic reload mechanism triggered by the exploit can cause temporary loss of wireless connectivity for all connected devices, leading to business disruption and potential security implications when network services become unavailable. The vulnerability's adjacency requirement means that attackers do not need sophisticated network reconnaissance or advanced exploitation capabilities, as they simply need to position themselves within the same broadcast domain to execute the attack. This characteristic significantly increases the attack surface and makes the vulnerability particularly dangerous in environments where physical security controls may be insufficient or where unauthorized network access is possible.
The vulnerability aligns with CWE-20, which describes "Improper Input Validation" as a fundamental weakness that occurs when software does not properly validate input data, leading to various security consequences including denial of service conditions. From an adversarial methodology perspective, this vulnerability maps to ATT&CK technique T1499.002, which involves network disruption through service denial attacks that target network infrastructure components. The exploitability characteristics make this vulnerability particularly attractive to threat actors who seek to disrupt business operations or create opportunities for additional attacks through network instability. Organizations should consider implementing network segmentation strategies to limit adjacent network access points and reduce the attack surface for such proximity-based exploits. The recommended mitigation approach involves immediate deployment of Cisco software patches and updates for affected versions, along with network monitoring to detect anomalous IAPP message traffic patterns that might indicate attempted exploitation of this vulnerability.
The broader implications of CVE-2019-1796 highlight the critical importance of input validation in network protocol implementations and demonstrate how seemingly minor validation gaps can result in significant operational disruptions. This vulnerability serves as a reminder that wireless network infrastructure components, which often operate as critical business systems, require rigorous security testing and validation of all message handling procedures. The attack vector's simplicity and the potential for widespread impact across multiple software versions indicate that this vulnerability likely represents a common pattern in network protocol implementation where defensive programming practices were insufficiently applied to protect against malformed data inputs. Organizations maintaining Cisco WLC deployments should conduct thorough vulnerability assessments and implement appropriate network controls to prevent unauthorized access to wireless infrastructure components that could enable exploitation of similar input validation weaknesses.