Users of social networks appear to want and need to share information online without necessarily thinking about the security consequences. Hackers and attackers have understood the potential vulnerabilities in social networks. This paper describes an architecture for adaptive information security systems, which could be applied to provide security services in social networks. The problem with most security architectures is that they do not provide adaptive security measures to environments and to culture of users. In addition, most security architectures provide technical security measures but fail to provide socio-technical measures. The enemies of ICT use both technical and social measures to attack ICT systems. This paper presents a security architecture that provides adaptive security measures and socio-technical measures in social networks.