The installation of Trend Micro PC-Cillin Internet Security 2005 12.00 build 1244, and probably previous versions, uses insecure default ACLs, which allows local users to cause a denial of service (disabled service) and gain system privileges by modifying or moving critical program files.

Multiple interpretation error in Trend Micro (1) PC-Cillin 2005 12.0.1244 with the 7.510.1002 engine and (2) OfficeScan 7.0 with the 7.510.1002 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."