An inexperienced and unskilled "hacker" who attempts to infiltrate or disrupt computer systems by running pre-fabricated scripts designed to crack those systems.
Which is why he has little patience for the ineffective (and, even more distressing to a true hacker, inelegant) attempts against his system he regularly observes with amusement.
He estimates 99% are launched by what security experts call "script kiddies." With no technical knowledge, these would-be 'crackers' (the Net term for malicious hackers) don't write their own code. They just drop in at one of the many illicit Web sites offering cracking programs, or scripts.
Elizabeth Weise, "Cracking the hacker myth," USA Today, May 6, 1998
Scripts are pre-packaged ways to find weaknesses in computer
systems. They've been around for years, but the growth of the
Internet has led to higher demand for such tools, especially among a
younger crowd dazzled by recent films such as The Net and Hackers.
They are known as "script kiddies," people who want to call
themselves hackers but who don't necessarily want to spend a lot of
time glued to a computer.
Leslie Gornstein, "Novice hackers netting bad rep," The Forth-Worth Star-Telegram, August 17, 1997
This phrase is one of the most damning that you could toss at a hacker wanna-be. In the meritocratic netherworld of cracking culture, status is based entirely on one's programming skills. So implying that someone merely piggybacks on the hard work of other people by using their scripts is a grievous insult, indeed. An equally wounding jab is the synonym script bunny.
The earliest citation below is actually the earliest mainstream media citation; I've seen this phrase on Usenet since about mid-1996.