This paper describes the results of the research conducted by SEC Consult Vulnerability Lab on the security of McAfee Application Control. This product is an example of an application whitelisting solution which can be used to further harden critical systems such as server systems in SCADA environments or client systems with high security requirements like administrative workstations. Application whitelisting is a concept which works by whitelisting all installed software on a system and after that prevent the execution of not whitelisted software. This should prevent the execution of malware and therefore protect against advanced persistent threat (APT) attacks. McAfee Application Control is an example of such a software. It can be installed on any system, however, the main field of application is the protection of highly critical infrastructures. While the core feature of the product is application whitelisting, it also supports additional security features including write and read protection as well as different memory corruption protections.