Morris Worm

The Morris worm or Internet worm of November 2, 1988 was one of the first computer worms distributed via the Internet. It was the first to gain significant mainstream media attention. It also resulted in the first felony conviction in the US under the 1986 Computer Fraud and Abuse Act. It was written by a graduate student at Cornell University, Robert Tappan Morris, and launched on November 2, 1988 from the computer systems of the Massachusetts Institute of Technology.

According to its creator, Robert Tappan Morris, the Morris worm was not written to cause damage, but to gauge the size of the Internet. The worm was released from MIT in the hope of suggesting that its creator studied there, which Morris did not (though Morris later became a tenured professor at MIT in 2006). It worked by exploiting known vulnerabilities in Unix sendmail, , and rsh/rexec, as well as weak passwords. Due to reliance on rsh (normally disabled on untrusted networks), fixes to sendmail, finger, the widespread use of network filtering, and improved awareness of the dangers of weak passwords, it should not succeed on a recent, properly configured system.

A supposedly unintended consequence of the code, however, caused it to be more damaging: a computer could be infected multiple times and each additional process would slow the machine down, eventually to the point of being unusable. This would have the same effect as a fork bomb and crash the computer several times. The main body of the worm could only infect DEC VAX machines running 4BSD, and Sun-3 systems. A portable C "grappling hook" component of the worm was used to pull over (download) the main body, and the grappling hook could run on other systems, loading them down and making them peripheral victims.

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