The problem here is that your security software is at risk. If your vendor codes an error, the virus author can and will detect it. For example, if your vendor should exclude a file from scanning, it’s possible the virus author will figure out which file (or type of file) that is and bury his code there. If the vendor excludes files from scanning or heuristics, it’s possible that virus author will figure out a way to corrupt that file.

That being said, there are other risks. As we have said, once software is on the desktop it affords virus authors an opportunity to reverse-engineer security software. The knowledge that reverse-engineering provides is invaluable to a virus author when building his next software attack. Third, virus authors can learn where the anti-virus vendors put there software and put the links to their software (directory folders, registry entries, etc.). This too is invaluable information. In fact, in some ways it teaches people intent on writing malicious software clues as to how to infiltrate the computers’ operating system, where registry entries need to be made to force software to be loaded every time a computer is started, etc.