CVE-2011-2040 in AnyConnect Secure Mobility Client
Summary
by MITRE
The helper application in Cisco AnyConnect Secure Mobility Client (formerly AnyConnect VPN Client) before 2.5.3041, and 3.0.x before 3.0.629, on Linux and Mac OS X downloads a client executable file (vpndownloader.exe) without verifying its authenticity, which allows remote attackers to execute arbitrary code via the url property to a Java applet, aka Bug ID CSCsy05934.
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Analysis
by VulDB Data Team • 12/02/2024
The vulnerability described in CVE-2011-2040 represents a critical security flaw in Cisco AnyConnect Secure Mobility Client versions prior to 2.5.3041 and 3.0.629 on Linux and Mac OS X platforms. This issue stems from the helper application's improper handling of executable file downloads, specifically the vpndownloader.exe file that is fetched from remote servers. The vulnerability allows remote attackers to execute arbitrary code by manipulating the url property within a Java applet, creating a dangerous attack vector that exploits trust relationships between the client and remote servers.
The technical flaw manifests in the absence of cryptographic verification or integrity checking mechanisms when downloading the vpndownloader.exe executable file. This design weakness enables attackers to substitute the legitimate executable with a malicious payload, which is then executed with the privileges of the AnyConnect client process. The vulnerability specifically affects the Java applet functionality where the url property can be manipulated to redirect the download to a malicious server hosting the compromised executable file. This type of attack falls under the category of Man-in-the-Middle (MITM) and supply chain compromise attacks, where attackers exploit the trust relationship between the client application and the download source.
The operational impact of this vulnerability is severe as it allows remote code execution without requiring user interaction or authentication. An attacker who can intercept network traffic or compromise a DNS server can deliver malicious payloads that execute with the privileges of the AnyConnect client, potentially leading to full system compromise. The vulnerability affects enterprise environments where AnyConnect is widely deployed for remote access, making it particularly dangerous for organizations that rely on VPN connectivity for secure remote access. This weakness enables attackers to establish persistent access, escalate privileges, and potentially move laterally within network environments.
Mitigation strategies for this vulnerability include immediate deployment of Cisco's security patches and updates to versions 2.5.3041 and 3.0.629 or later. Organizations should also implement network monitoring to detect suspicious download patterns and ensure that all network traffic is properly inspected for malicious content. The implementation of certificate pinning mechanisms and digital signature verification for all downloaded executables provides additional protection against similar supply chain attacks. This vulnerability aligns with CWE-502, which addresses deserialization of untrusted data, and maps to ATT&CK technique T1190 for exploit public-facing application, highlighting the need for comprehensive network security controls and application hardening measures to prevent unauthorized code execution in enterprise environments.