In Sophos Tester Tool 3.2.0.7 Beta, the driver loads (in the context of the application used to test an exploit or ransomware) the DLL using a payload that runs from NTDLL.DLL (so, it's run in userland), but the driver doesn't perform any validation of this DLL (not its signature, not its hash, etc.). A person can change this DLL in a local way, or with a remote connection, to a malicious DLL with the same name -- and when the product is used, this malicious DLL will be loaded, aka a DLL Hijacking attack.