logic bomb
n. A computer virus set for a timed release, and when the virus detonates, it deliberately disrupts, modifies, or erases data.
Omega Engineering learned firsthand the dangers of the disgruntled employee after a timed virus, known as a logic bomb, wiped out all of its research, development, and production programs in one fell swoop. (The tape backup also was destroyed.) In January, charges were filed against 31-year-old Timothy Lloyd, an Omega programmer, for placing the bomb on the network, which detonated 10 days after his termination.
—Deborah Radcliff, “The danger within; Internal employees — not outside hackers — can be a time bomb waiting to blow,” InfoWorld, April 20, 1998
The weapons of information warfare are mostly computer software, like destructive logic bombs and eavesdropping sniffers, or advanced electronic hardware, like a high-energy radio frequency device, known as a HERF gun.
—Steve Lohr, “Get Ready. Aim. Zap; National Security Experts Plan for Wars Whose Targets and Weapons Are All Digital,” The New York Times, September 30, 1996
1979 (earliest)
Mr. MacNeil: What are some of the typical crimes?

Mr. Parker: Well, it takes a whole spectrum of problems, all the way from what I refer to as data diddling where you're merely changing the date before it goes into the computer, and after it comes out of the computer, all the way to the other extreme of very sophisticated crimes, using Trojan horses, logic bombs, salamis, data leakage.
—“Computer Crime,” The MacNeil-Lehrer Report, April 11, 1979
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