Social EngineeringOriginal issue date: April 18, 1991
Last revised: September 18, 1997
Attached copyright statement
A complete revision history is at the end of this file.
I. DescriptionThe Computer Emergency Response Team/Coordination Center (CERT/CC) has received several incident reports concerning users receiving requests to take an action that results in the capturing of their password. The request could come in the form of an e-mail message, a broadcast, or a telephone call. The latest ploy instructs the user to run a "test" program, previously installed by the intruder, which will prompt the user for his or her password. When the user executes the program, the user's name and password are e-mailed to a remote site. We are including an example message at the end of this advisory.
These messages can appear to be from a site administrator or root. In reality, they may have been sent by an individual at a remote site, who is trying to gain access or additional access to the local machine via the user's account.
While this advisory may seem very trivial to some experienced users, the fact remains that MANY users have fallen for these tricks (refer to CERT Advisory CA-91.03).
II. ImpactAn intruder can gain access to a system through the unauthorized use of the (possibly privileged) accounts whose passwords have been compromised. This problem could affect all systems, not just UNIX systems or systems on the Internet.
III. SolutionThe CERT/CC recommends the following actions:
- Any users receiving such a request should verify its authenticity with their system administrator before acting on the instructions within the message. If a user has received this type of request and actually entered a password, he/she should immediately change his/her password to a new one and alert the system administrator.
System administrators should check with their user communities to ensure that no user has followed the instructions in such a message. Further, the system should be carefully examined for damage or changes that the intruder may have caused. We also ask that you contact the CERT/CC.
The CERT/CC urges system administrators to educate their users so that they will not fall prey to such tricks.
SAMPLE MESSAGE as received by the CERT (including spelling errors, etc.)
OmniCore is experimenting in online - high resolution graphics display on the UNIX BSD 4.3 system and it's derivitaves. But, we need you're help in testing our new product - TurboTetris. So, if you are not to busy, please try out the ttetris game in your machine's /tmp directory. just type:
/tmp/ttetrisBecause of the graphics handling and screen-reinitialazation, you will be prompted to log on again. Please do so, and use your real password. Thanks you for your support. You'll be hearing from us soon!
END OF SAMPLE MESSAGE
This document is available from: http://www.preview.cert.org/advisories/CA-1991-04.html
CERT/CC Contact Information
CERT Coordination Center
Software Engineering Institute
Carnegie Mellon University
Pittsburgh PA 15213-3890
Phone: +1 412-268-7090 (24-hour hotline)
Fax: +1 412-268-6989
CERT/CC personnel answer the hotline 08:00-17:00 EST(GMT-5) / EDT(GMT-4) Monday through Friday; they are on call for emergencies during other hours, on U.S. holidays, and on weekends.
We strongly urge you to encrypt sensitive information sent by email. Our public PGP key is available from
If you prefer to use DES, please call the CERT hotline for more information.
Getting security information
CERT publications and other security information are available from our web site
* "CERT" and "CERT Coordination Center" are registered in the U.S. Patent and Trademark Office.
Any material furnished by Carnegie Mellon University and the Software Engineering Institute is furnished on an "as is" basis. Carnegie Mellon University makes no warranties of any kind, either expressed or implied as to any matter including, but not limited to, warranty of fitness for a particular purpose or merchantability, exclusivity or results obtained from use of the material. Carnegie Mellon University does not make any warranty of any kind with respect to freedom from patent, trademark, or copyright infringement.
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Copyright 1991 Carnegie Mellon University.
September 18,1997 Attached Copyright Statement