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CERT Security Advisory (Keystroke logging)
NOTICE: TO ALL CONCERNED Certain text files and messages contained on this site deal with activities and devices which would be in violation of various Federal, State, and local laws if actually carried out or constructed. The webmasters of this site do not advocate the breaking of any law. Our text files and message bases are for informational purposes only. We recommend that you contact your local law enforcement officials before undertaking any project based upon any information obtained from this or any other web site. We do not guarantee that any of the information contained on this system is correct, workable, or factual. We are not responsible for, nor do we assume any liability for, damages resulting from the use of any information on this site.
CA-92:19 CERT Advisory
December 7, 1992
Keystroke Logging Banner
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The CERT Coordination Center has received information from the United States
Department of Justice, General Litigation and Legal Advice Section, Criminal
Division, regarding keystroke monitoring by computer systems administrators,
as a method of protecting computer systems from unauthorized access.
The information that follows is based on the Justice Department's advice
to all federal agencies. CERT strongly suggests adding a notice banner
such as the one included below to all systems. Sites not covered by U.S.
law should consult their legal counsel.
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The legality of such monitoring is governed by 18 U.S.C. section 2510
et seq. That statute was last amended in 1986, years before the words
"virus" and "worm" became part of our everyday vocabulary. Therefore,
not surprisingly, the statute does not directly address the propriety
of keystroke monitoring by system administrators.
Attorneys for the Department have engaged in a review of the statute
and its legislative history. We believe that such keystroke monitoring
of intruders may be defensible under the statute. However, the statute
does not expressly authorize such monitoring. Moreover, no court has
yet had an opportunity to rule on this issue. If the courts were to
decide that such monitoring is improper, it would potentially give rise
to both criminal and civil liability for system administrators.
Therefore, absent clear guidance from the courts, we believe it is
advisable for system administrators who will be engaged in such
monitoring to give notice to those who would be subject to monitoring
that, by using the system, they are expressly consenting to such
monitoring. Since it is important that unauthorized intruders be given
notice, some form of banner notice at the time of signing on to the
system is required. Simply providing written notice in advance to only
authorized users will not be sufficient to place outside hackers on
notice.
An agency's banner should give clear and unequivocal notice to
intruders that by signing onto the system they are expressly consenting
to such monitoring. The banner should also indicate to authorized
users that they may be monitored during the effort to monitor the
intruder (e.g., if a hacker is downloading a user's file, keystroke
monitoring will intercept both the hacker's download command and the
authorized user's file). We also understand that system administrators
may in some cases monitor authorized users in the course of routine
system maintenance. If this is the case, the banner should indicate
this fact. An example of an appropriate banner might be as follows:
This system is for the use of authorized users only.
Individuals using this computer system without authority, or in
excess of their authority, are subject to having all of their
activities on this system monitored and recorded by system
personnel.
In the course of monitoring individuals improperly using this
system, or in the course of system maintenance, the activities
of authorized users may also be monitored.
Anyone using this system expressly consents to such monitoring
and is advised that if such monitoring reveals possible
evidence of criminal activity, system personnel may provide the
evidence of such monitoring to law enforcement officials.
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Each site using this suggested banner should tailor it to their precise
needs. Any questions should be directed to your organization's legal
counsel.
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The CERT Coordination Center wishes to thank Robert S. Mueller, III,
Scott Charney and Marty Stansell-Gamm from the United States Department
of Justice for their help in preparing this Advisory.
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If you believe that your system has been compromised, contact the CERT
Coordination Center or your representative in FIRST (Forum of Incident
Response and Security Teams).
Internet E-mail: [email protected]
Telephone: 412-268-7090 (24-hour hotline)
CERT personnel answer 7:30 a.m.-6:00 p.m. EST(GMT-5)/EDT(GMT-4),
on call for emergencies during other hours.
CERT Coordination Center
Software Engineering Institute
Carnegie Mellon University
Pittsburgh, PA 15213-3890
Past advisories, information about FIRST representatives, and other
information related to computer security are available for anonymous FTP
from cert.org (192.88.209.5).
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