In this paper we present an application of the MATINE method for investigating dependencies in antivirus (AV) software and some vulnerabilities arising from these dependencies. Previously, this method has been effectively used to find vulnerabilities in network protocols. Because AV software is as vulnerable as any other software and has a great security impact, we decided to use this method to find vulnerabilities in AV software. These findings may have implications to critical infrastructure, for the use of AV is often considered obligatory. The results were obtained by gathering semantic data on AV vulnerabilities, analyisis of the data and content analysis of media follow-up. The results indicate, that different aspects of AV software should be observed in the context of critical infrastructure planning and management.