The files are not something that the average user would come across on a daily basis, he added. “MDB files are blocked by default in most installations of Internet Explorer and Outlook Express ...

Security experts say that the exploit won't be widespread because numerous companies block the use of .mdb files.

No matter what kind of patch it produces or when it pushes a fix to users, Microsoft can’t change the .mdb file format to make it less dangerous, according to Reavey.