THE ART OF COMPUTER VIRUS RESEARCH AND DEFENSE [Electronic resources]

3.9. Date and Time Dependency

Tyrell: What seems to be the problem?

Roy: Death!

Tyrell: Death. Well, I am afraid that's a little out of my jurisdiction.

Roy: I want more life...

Blade Runner, 1982

Several viruses replicate only within a certain time frame of the day. Others refuse to replicate before or after a certain date. For instance, the W32/Welchia worm only attempted to invade systems until January 2004.Chapter 10.