928 F.2d 504 (2nd Cir. 1991), 774, United States v. Morris

Docket Nº:774, Docket 90-1336.
Citation:928 F.2d 504
Party Name:UNITED STATES of America, Appellee, v. Robert Tappan MORRIS, Defendant-Appellant.
Case Date:March 07, 1991
Court:United States Courts of Appeals, Court of Appeals for the Second Circuit

Page 504

928 F.2d 504 (2nd Cir. 1991)

UNITED STATES of America, Appellee,


Robert Tappan MORRIS, Defendant-Appellant.

No. 774, Docket 90-1336.

United States Court of Appeals, Second Circuit

March 7, 1991

Argued Dec. 4, 1990.

Thomas A. Guidoboni, Washington, D.C., for defendant-appellant.

Ellen R. Meltzer, U.S. Dept. of Justice, Washington, D.C. (Frederick J. Scullin, Jr., U.S. Atty., Syracuse, N.Y., Mark D. Rasch, U.S. Dept. of Justice, Washington, D.C., on the brief), for appellee.

Page 505

Before NEWMAN and WINTER, Circuit Judges, and DALY, District Judge. [*]

JON O. NEWMAN, Circuit Judge:

This appeal presents two narrow issues of statutory construction concerning a provision Congress recently adopted to strengthen protection against computer crimes. Section 2(d) of the Computer Fraud and Abuse Act of 1986, 18 U.S.C. Sec. 1030(a)(5)(A) (1988), punishes anyone who intentionally accesses without authorization a category of computers known as "[f]ederal interest computers" and damages or prevents authorized use of information in such computers, causing loss of $1,000 or more. The issues raised are (1) whether the Government must prove not only that the defendant intended to access a federal interest computer, but also that the defendant intended to prevent authorized use of the computer's information and thereby cause loss; and (2) what satisfies the statutory requirement of "access without authorization."

These questions are raised on an appeal by Robert Tappan Morris from the May 16, 1990, judgment of the District Court for the Northern District of New York (Howard G. Munson, Judge) convicting him, after a jury trial, of violating 18 U.S.C. Sec. 1030(a)(5)(A). Morris released into INTERNET, a national computer network, a computer program known as a "worm" 1 that spread and multiplied, eventually causing computers at various educational institutions and military sites to "crash" or cease functioning.

We conclude that section 1030(a)(5)(A) does not require the Government to demonstrate that the defendant intentionally prevented authorized use and thereby caused loss. We also find that there was sufficient evidence for the jury to conclude that Morris acted "without authorization" within the meaning of section 1030(a)(5)(A). We therefore affirm.


In the fall of 1988, Morris was a first-year graduate student in Cornell University's computer science Ph.D. program. Through undergraduate work at Harvard and in various jobs he had acquired significant computer experience and expertise. When Morris entered Cornell, he was given an account on the computer at the Computer Science Division. This account gave him explicit authorization to use computers at Cornell. Morris engaged in various discussions with fellow graduate students about the security of computer networks and his ability to penetrate it.

In October 1988, Morris began work on a computer program, later known as the INTERNET "worm" or "virus." The goal of this program was to demonstrate the inadequacies of current security measures on computer networks by exploiting the security defects that Morris had discovered. The tactic he selected was release of a worm into network computers. Morris designed the program to spread across a national network of computers after being inserted at one computer location connected to the network. Morris released the worm into INTERNET, which is a group of national networks that connect university, governmental, and military computers around the country. The network permits communication and transfer of information between computers on the network.

Morris sought to program the INTERNET worm to spread widely without drawing attention to itself. The worm was supposed to occupy little computer operation time, and thus not interfere with normal use of the computers. Morris programmed the worm to make it difficult to detect and read, so that other programmers would not be able to "kill" the worm easily.

Page 506

Morris also wanted to ensure that the worm did not copy itself onto a computer that already had a copy. Multiple copies of the worm on a computer would make the worm easier to detect and would bog down the system and ultimately cause the computer to crash. Therefore, Morris designed the worm to "ask" each computer whether it already had a copy of the worm. If it responded "no," then the worm would copy onto the computer; if it responded "yes," the worm would not duplicate. However, Morris was concerned that other programmers could kill the worm by programming their own computers to falsely respond "yes" to the question. To circumvent this protection, Morris programmed the worm to duplicate itself every seventh time it received a "yes" response. As it turned out, Morris underestimated the number of times a computer would be asked the question, and his one-out-of-seven ratio resulted in far more copying than he had anticipated. The worm was also designed so that it would be killed when a computer was shut down, an event that typically occurs once every week or two. This would have prevented the worm from accumulating on one computer, had Morris correctly estimated the likely rate of reinfection.

Morris identified four ways in which the worm could break into computers on the network:

(1) through a "hole" or "bug" (an error) in SEND MAIL, a computer program that transfers and receives electronic mail on a computer;

(2) through a bug in the "finger demon" program, a program that permits a person to obtain limited information about the users of another computer;

(3) through the "trusted hosts" feature, which permits a user with certain privileges on one computer to have equivalent privileges on another computer without using a password; and

(4) through a program of password guessing, whereby various combinations of letters are tried out in rapid sequence in the hope that one will be an authorized user's password, which is entered to permit whatever level of activity that user is authorized to perform.

On November 2, 1988, Morris released the worm from a computer at the Massachusetts Institute of Technology. MIT was selected to disguise the fact that the worm came from Morris at Cornell. Morris soon discovered that the worm was replicating and reinfecting machines at a much faster rate than he had anticipated. Ultimately, many machines at locations around the country either crashed or became "catatonic." When Morris realized what was happening, he contacted a friend at Harvard to discuss a solution. Eventually, they sent an anonymous message from Harvard over the network, instructing programmers how to kill the worm and prevent reinfection. However, because the network route was clogged, this message...

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