Abstract: OpenVPN, as a typical application for channel encryption, faces severe threats from large-scale surveillance and subversion attacks on its security. By studying the communication characteristics of the four stages of the protocol and conducting a detailed analysis of the attack surfaces and conditions at each stage, researchers construct a security game model and attack framework for subversion attacks targeting the data encryption and decryption stages of the OpenVPN protocol. To address the challenge of traditional models struggling to accurately assess attack effectiveness in complex real-world communication environments, a definition of attack advantage is proposed, with data decryption probability serv- ing as the primary evaluation criterion. This aids in a more precise quantitative assessment of attack effectiveness under the influence of different factors. Based on this, an IV (Initialization Vector) replacement attack method is designed and instantiated, with the fundamental properties of the attack method proven. Systematic analysis and comparison of attack advantages against different encryption algorithms of the OpenVPN protocol are conducted, and specific mitigation measures are proposed.

Key words: mass surveillance, subversion attack, OpenVPN protocol