CVE-2010-3901 in OpenConnect
Summary
by MITRE
OpenConnect before 2.25 does not properly validate X.509 certificates, which allows man-in-the-middle attackers to spoof arbitrary AnyConnect SSL VPN servers via a crafted server certificate that (1) does not correspond to the server hostname or (2) is presented in circumstances involving a missing --cafile configuration option.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 01/20/2025
The vulnerability described in CVE-2010-3901 affects OpenConnect versions prior to 2.25 and represents a critical weakness in the SSL/TLS certificate validation process. This flaw enables man-in-the-middle attackers to successfully impersonate legitimate AnyConnect SSL VPN servers by presenting maliciously crafted certificates that bypass essential security checks. The vulnerability specifically targets the X.509 certificate validation mechanism, which is fundamental to establishing secure communications between clients and servers in SSL VPN environments.
The technical implementation of this vulnerability stems from insufficient certificate validation logic within OpenConnect's SSL handling code. When a client connects to a VPN server, the software should verify that the presented certificate matches the expected hostname and that the certificate chain is properly validated against trusted Certificate Authorities. However, OpenConnect versions before 2.25 failed to perform these critical checks, allowing attackers to present certificates that either do not correspond to the actual server hostname or are presented without proper certificate authority validation. This weakness creates a scenario where an attacker can establish a false sense of security by presenting a certificate that appears legitimate to the client but is actually controlled by the attacker.
The operational impact of this vulnerability extends beyond simple certificate validation failures and represents a significant threat to enterprise security infrastructure. Organizations relying on AnyConnect SSL VPN services for remote access are particularly vulnerable, as attackers can intercept and manipulate communications without detection. The vulnerability becomes more pronounced when the --cafile configuration option is missing or improperly configured, as this removes an additional layer of certificate validation that would otherwise help prevent such attacks. This weakness can lead to complete compromise of VPN sessions, allowing attackers to intercept sensitive data, perform unauthorized actions, and potentially gain access to internal network resources that should be protected by the VPN infrastructure.
The implications of this vulnerability align with several CWE categories including CWE-295 for improper certificate validation and CWE-310 for cryptographic weaknesses. From an ATT&CK framework perspective, this vulnerability maps to techniques involving credential access through man-in-the-middle attacks and privilege escalation via network infiltration. Organizations should implement immediate mitigations including updating to OpenConnect version 2.25 or later, ensuring proper --cafile configuration is always used, and implementing additional network monitoring to detect anomalous certificate behavior. Security teams should also consider implementing certificate pinning mechanisms and regular certificate validation audits to prevent exploitation of similar weaknesses in other network security tools. The vulnerability demonstrates the critical importance of robust certificate validation in SSL/TLS implementations and serves as a reminder of the potential consequences when cryptographic security controls are insufficiently implemented in network security solutions.