Multiple interpretation error in (1) McAfee Internet Security Suite 7.1.5 version 9.1.08 with the 4.4.00 engine and (2) McAfee Corporate 8.0.0 patch 10 with the 4400 engine allows remote attackers to bypass virus scanning via a file such as BAT, HTML, and EML with an "MZ" magic byte sequence which is normally associated with EXE, which causes the file to be treated as a safe type that could still be executed as a dangerous file type by applications on the end system, as demonstrated by a "triple headed" program that contains EXE, EML, and HTML content, aka the "magic byte bug."