BC.Exploit is a Windows-only exploit that can be used to run arbitrary code on Windows XP, Vista, and 7 running Microsoft Publisher 2003 and Microsoft Publisher 2007. There is a memory issue in Publisher that allows an attacker to create a booby-trapped Publisher file which will infect a computer with malware if it opens the file in Publisher.
This vulnerability only affects Windows computers and only if they are running Microsoft Publisher. The vulnerability can only be found in .pub files; if you see it in other file types (such as Excel files), it's a false positive.
