This book constitutes the refereed proceedings of the 5th International Conference on Mathematical Methods, Models, and Architectures for Computer Network Security, MMM-ACNS 2010, held in St. Petersburg, Russia in September 2010. The 16 revised full papers and 6 revised short papers presented together with 5 invited papers were carefully reviewed and selected from a total of 54 submissions. The papers are organized in topical sections on security modeling and covert channels, security policies and formal analysis of security properties, authentication, authorization, access control and public key cryptography, intrusion and malware detection, security of multi-agent systems and software protection, as well as. adaptive security, security analysis and virtualization.