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- **************************************************************************
- Security Bulletin 9207 DISA Defense Communications System
- February 26, 1992 Published by: DDN Security Coordination Center
- (SCC@NIC.DDN.MIL) 1-(800) 365-3642
-
- DEFENSE DATA NETWORK
- SECURITY BULLETIN
-
- The DDN SECURITY BULLETIN is distributed by the DDN SCC (Security
- Coordination Center) under DISA contract as a means of communicating
- information on network and host security exposures, fixes, and concerns
- to security and management personnel at DDN facilities. Back issues may
- be obtained via FTP (or Kermit) from NIC.DDN.MIL [192.112.36.5] using
- login="anonymous" and password="guest". The bulletin pathname is
- scc/ddn-security-yynn (where "yy" is the year the bulletin is issued
- and "nn" is a bulletin number, e.g., scc/ddn-security-9207).
- **************************************************************************
-
- + - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - +
- ! !
- ! The following important advisory was issued by the Computer !
- ! Emergency Response Team (CERT) and is being relayed unedited !
- ! via the Defense Information Systems Agency's Security !
- ! Coordination Center distribution system as a means of providing !
- ! DDN subscribers with useful security information. !
- ! !
- + - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - +
-
- ===========================================================================
- CA-92:04 CERT Advisory
- February 25, 1992
- AT&T /usr/etc/rexecd Vulnerability
-
- ---------------------------------------------------------------------------
-
- The Computer Emergency Response Team/Coordination Center (CERT/CC) has
- received information concerning a vulnerability in AT&T TCP/IP Release
- 4.0 running on SVR4 systems for both the 386/486 and 3B2 RISC platforms.
-
- The existing error, in the remote execution server /usr/etc/rexecd, has
- been corrected, and a new executable for rexecd is available from AT&T
- by calling 800-543-9935. Patches may be obtained outside the U.S. by
- calling your local technical support. The numbers associated with the
- fix are 5127 (3.5" media) and 5128 (5.25" media).
-
- The problem does not exist in TCP/IP release 3.2 for SVR3, or any earlier
- versions of the TCP/IP product running on either the 3B2 or 386 platforms.
-
- The version of TCP/IP distributed with SVR4 by UNIX(r) System Laboratories,
- Inc. (a subsidiary of AT&T) does not contain this vulnerability.
-
- UNIX(r) is a registered trademark of UNIX System Laboratories, Inc.
-
- ---------------------------------------------------------------------------
-
- I. Description
-
- A vulnerability has been identified where root privileges may be
- accessed through the use of /usr/etc/rexecd.
-
- II. Impact
-
- A user on a remote machine may be able to run commands as root on
- the target host (the host running the affected /usr/etc/rexecd).
-
- III. Solution
-
- 1. Administrators of affected systems should execute, as root, the
- following command to immediately turn off access to rexecd until
- the new binary can be obtained.
-
- # chmod 400 /usr/etc/rexecd
-
- 2. Obtain and install the new patch. The fix will be supplied as
- one diskette, and it comes with one page of instructions documenting
- the procedure to replace the existing /usr/etc/rexecd binary.
-
- ---------------------------------------------------------------------------
- The CERT/CC wishes to thank Bradley E. Smith, Network & Technical Services,
- Bradley University, for bringing this vulnerability to our attention and for
- providing a corresponding solution. We would also like to thank AT&T for
- their very quick response to this problem.
- ---------------------------------------------------------------------------
-
- 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.sei.cmu.edu
- 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.sei.cmu.edu (192.88.209.5).
-
-
- ****************************************************************************
-
- The point of contact for MILNET security-related incidents is the
- Security Coordination Center (SCC).
-
- E-mail address: SCC@NIC.DDN.MIL
-
- Telephone: 1-(800)-365-3642
- NIC Help Desk personnel are available from 7:00 a.m.-7:00 p.m. EST,
- Monday through Friday except on federal holidays.
-
- ****************************************************************************
-