ExploreZip (also known as I-Worm.ZippedFiles) is a destructive computer worm that attacks machines running Microsoft Windows. It was first discovered in Israel on June 6, 1999. The worm contains a malicious payload, and utilizes Microsoft Outlook, Outlook Express, or Exchange to mail itself out by replying to unread messages in the user's inbox. The worm also searches mapped drives and networked computers for Windows installations. If found, it copies itself to the Windows folder of the remote computer and then modifies the Win.ini file of the infected computer. On January 8, 2003, Symantec discovered a packed variant of this threat which exhibits the same characteristics.