CVE-2010-3903 in OpenConnect
Summary
by MITRE
Unspecified vulnerability in OpenConnect before 2.23 allows remote AnyConnect SSL VPN servers to cause a denial of service (application crash) via a 404 HTTP status code.
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Analysis
by VulDB Data Team • 02/07/2019
The vulnerability identified as CVE-2010-3903 represents a significant security flaw within the OpenConnect SSL VPN client software ecosystem. This issue affects versions prior to 2.23 and specifically targets the client's handling of HTTP responses from remote AnyConnect SSL VPN servers. The vulnerability manifests when the client encounters a 404 HTTP status code, which triggers an unexpected application behavior leading to a complete system crash. This type of vulnerability falls under the category of denial of service attacks, where legitimate users are denied access to the VPN service due to the application's inability to properly process error responses from the server infrastructure.
The technical root cause of this vulnerability lies in the insufficient input validation and error handling mechanisms within the OpenConnect client implementation. When the client receives a 404 HTTP status code from a remote server, the application fails to properly sanitize or handle this specific error response, resulting in a memory corruption or stack overflow condition that ultimately leads to the application termination. This flaw demonstrates poor defensive programming practices and highlights the critical importance of robust error handling in network security applications. The vulnerability is particularly concerning because it can be exploited remotely without requiring authentication or special privileges, making it an attractive target for malicious actors seeking to disrupt VPN services.
From an operational perspective, this vulnerability creates substantial risk for organizations relying on OpenConnect for secure remote access. The denial of service condition can result in extended downtime for remote workers and IT personnel who depend on VPN connectivity for business operations. The impact extends beyond simple service disruption as it can affect critical business processes, emergency response systems, and remote work capabilities that organizations have increasingly come to depend upon. The vulnerability's remote exploitability means that attackers can potentially trigger service outages from anywhere on the internet, making it particularly dangerous for organizations with distributed workforces or those operating in regulated environments where continuous availability is mandated.
Organizations should immediately implement mitigations including upgrading to OpenConnect version 2.23 or later, which contains the necessary patches to address this vulnerability. Network administrators should also consider implementing additional monitoring and alerting mechanisms to detect unusual HTTP status code patterns that might indicate exploitation attempts. The vulnerability aligns with CWE-248, which addresses "Uncaught Exception," and represents a classic example of how improper error handling can lead to application instability. From an ATT&CK framework perspective, this vulnerability maps to the T1499.004 technique related to "Unauthorized Remote Access" and demonstrates how seemingly benign HTTP responses can be weaponized to achieve denial of service objectives. Organizations should also review their incident response procedures to ensure they can quickly identify and remediate similar vulnerabilities in other network security tools and applications.