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Home : Advisories : Internet Intruder Activity

Title: Internet Intruder Activity
Released by: CERT
Date: 17th February 1992
Printable version: Click here

Hash: SHA1



Last Revised:  September 19,1997

                Attached copyright statement

                               CERT Advisory

                              February 17, 1992

                          Internet Intruder Activity

- ---------------------------------------------------------------------------

The Computer Emergency Response Team/Coordination Center (CERT/CC) has

received information regarding a significant intrusion incident on the

Internet.  Systems administrators should be aware that many systems on

the Internet have been compromised due to this activity.  To identify

whether your systems have been affected by the activity we recommend

that all system administrators check for the signs of intrusion

detailed in this advisory.

This advisory describes the activities that have been identified as

part of this particular incident.  This does not address the

possibility that systems may have been compromised due to other,

unrelated intrusion activity.

- ---------------------------------------------------------------------------

I.   Description

     The intruders gained initial access to a host by discovering a

     password for a user account on the system.  They then attempted

     to become root on the compromised system.

II.  Impact


     Having gained root access on a system, the intruders installed

     trojan binaries that captured account information for both

     local and remote systems.  They also installed set-uid root

     shells to be used for easy root access.

III. Solution 

     A. Check your systems for signs of intrusion due to this incident.

        1. Check the su, ftpd, and ftp binaries (for example, "/bin/su",

           "/usr/ucb/ftp" and "/usr/etc/in.ftpd" on Sun systems)

           against copies from distribution media.

        2. Check for the presence of any of the following files:

           "/usr/etc/..." (dot dot dot), "/var/crash/..." (dot dot dot), 

           "/usr/etc/.getwd", "/var/crash/.getwd", or 

           "/usr/kvm/..." (dot dot dot).

        3. Check for the presence of "+" in the "/etc/hosts.equiv" file.

        4. Check the home directory for each entry in the "/etc/passwd"

           file for the presence of a ".rhosts" file containing

           "+ +" (plus space plus).

        5. Search the system for the presence of the following set-uid

           root files: "wtrunc" and ".a".

        6. Check for the presence of the set-uid root file "/usr/lib/lpx".

     B. Take the following steps to secure your systems.

        1. Save copies of the identified files to removable media.

        2. Replace any modified binaries with copies from

           distribution media.

        3. Remove the "+" entry from the "/etc/hosts.equiv" file and 

           the "+ +" (plus space plus) entry from any ".rhosts" files.

        4. Remove any of the set-uid root files that you find, which are

           mentioned in A5 or A6 above.


        5. Change every password on the system.

        6. Inspect the files mentioned in A2 above for references

           to other hosts.

- ---------------------------------------------------------------------------

If you believe that your system has been compromised, contact CERT/CC or

your representative in FIRST (Forum of Incident Response and Security Teams).

Internet E-mail: cert@cert.org

Telephone: 412-268-7090 (24-hour hotline)

           CERT/CC personnel answer 7:30 a.m.-6:00 p.m. EST(GMT-5)/EDT(GMT-4),

           on call for emergencies during other hours.

Computer Emergency Response Team/Coordination Center (CERT/CC)

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 (

- -----------------------------------------------------------------------------

Copyright 1992 Carnegie Mellon University. Conditions for use, disclaimers,

and sponsorship information can be found in

http://www.cert.org/legal_stuff.html and http://ftp.cert.org/pub/legal_stuff .

If you do not have FTP or web access, send mail to cert@cert.org with

"copyright" in the subject line.

CERT is registered in the U.S. Patent and Trademark Office.


Revision History:

September 19,1997  Attached Copyright Statement


Version: PGP for Personal Privacy 5.0

Charset: noconv





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