"Zip-of-death" describes a subterfuge designed to bring down a network by overwhelming the antivirus software and/or network traffic checking security applications.
Using special techniques, a hacker can compress a file down to as little as 500KB, that, when decompressed, may reach 15GB or more in size. Another version of the exploit involves compressing such a large number of files, that, when decompressed, it can crash the system.
IWSS allows you to set limits on the size, as well as the number of files it will extract from a compressed archive. Whenever the limit is reached, IWSS will stop decompressing, delete all extracted files, and take the action specified for "uncleanable" files.