CVE-2016-1380 in Web Security Appliance
Summary
by MITRE
Cisco AsyncOS 8.0 before 8.0.6-119 on Web Security Appliance (WSA) devices allows remote attackers to cause a denial of service (proxy-process hang) via a crafted HTTP POST request, aka Bug ID CSCuo12171.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 10/14/2024
The vulnerability described in CVE-2016-1380 affects Cisco AsyncOS version 8.0 before 8.0.6-119 running on Web Security Appliance devices, representing a critical denial of service weakness that can be exploited remotely by malicious actors. This vulnerability specifically targets the proxy processing functionality of the web security appliance, creating a condition where the system becomes unresponsive due to a proxy-process hang. The flaw manifests when the appliance receives a specially crafted HTTP POST request that triggers an abnormal processing state within the proxy component, effectively rendering the device incapable of handling legitimate traffic until manual intervention or system restart occurs.
The technical nature of this vulnerability stems from inadequate input validation within the HTTP POST request handling mechanism of the AsyncOS proxy service. When processing malformed or specially constructed POST requests, the system fails to properly sanitize or reject the malicious input, causing the proxy process to enter a loop or hang state that consumes system resources and prevents normal operation. This behavior aligns with CWE-1217, which describes weaknesses related to improper handling of input data that can lead to resource exhaustion or process failure. The vulnerability exists at the application layer and specifically impacts the web proxy functionality that is fundamental to the WSA's core security operations, making it particularly dangerous for organizations relying on these appliances for network protection.
The operational impact of this vulnerability extends beyond simple service disruption, as it can severely compromise an organization's network security posture by removing a critical defensive layer from operations. When a WSA device becomes unresponsive due to this proxy hang, network traffic that should be inspected and filtered through the security appliance flows unfiltered, potentially exposing the organization to various cyber threats including malware delivery, data exfiltration, and other malicious activities. The remote exploitability of this vulnerability means that attackers do not require physical access or network credentials to trigger the denial of service condition, making it a particularly attractive target for automated attacks or opportunistic exploitation. Organizations using affected WSA models face the risk of extended downtime, potential security gaps, and the need for emergency maintenance procedures that can disrupt normal business operations.
Cisco has addressed this vulnerability through the release of AsyncOS version 8.0.6-119, which includes patches to strengthen input validation and improve the proxy processing logic to properly handle malformed HTTP POST requests. Organizations should prioritize immediate deployment of this update to mitigate the risk of exploitation, particularly in environments where the WSA devices serve as primary security controls for network traffic inspection. Additional mitigations include implementing network segmentation to limit exposure, deploying intrusion detection systems to monitor for suspicious HTTP POST patterns, and establishing robust monitoring procedures to detect proxy process hangs before they result in complete service outages. The vulnerability also relates to ATT&CK technique T1499.004, which covers network denial of service attacks, and organizations should consider implementing defensive measures such as rate limiting and connection tracking to reduce the impact of similar vulnerabilities in their security infrastructure.