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- **************************************************************************
- Security Bulletin 9214 DISA Defense Communications System
- May 27, 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-9214).
- **************************************************************************
- + - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - +
- ! !
- ! 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-92:10 CERT Advisory
- May 26, 1992
- AIX crontab Vulnerability
-
- ---------------------------------------------------------------------------
-
- The Computer Emergency Response Team/Coordination Center (CERT/CC) has
- received information concerning a vulnerability in crontab(1) in version 3.2
- of IBM's AIX operating system.
-
- IBM is aware of this problem, and a fix is available as apar number "ix26997"
- for AIX version 3.2. The version information for the patched /usr/bin/crontab
- is shown in the following what(1) output:
-
- % what /usr/bin/crontab
- 04 1.23 com/cmd/cntl/cron/crontab.c, cmdcntl, bos320, 9218320f 4/8/92 11:50:42
- 07 1.8 com/cmd/cntl/cron/permit.c, bos, bos320 4/25/91 17:16:59
- 11 1.15 com/cmd/cntl/cron/cronsub.c, bos, bos320 8/18/91 20:42:32
- 06 1.9 com/cmd/cntl/cron/funcs.c, bos, bos320 6/8/91 21:22:40
-
- If your crontab contains modules older than the above output indicates, we
- suggest that you install the fix.
-
- ---------------------------------------------------------------------------
-
- I. Description
-
- The distributed version of /usr/bin/crontab contains a security
- vulnerability.
-
-
- II. Impact
-
- Local users can gain unauthorized root access to the system.
-
-
- III. Solution
-
- The CERT/CC suggests that sites install the fix that IBM has made
- available. As an interim step, we suggests that sites prevent all
- non-root users from running /usr/bin/crontab by removing (or renaming)
- the /var/adm/cron/cron.allow and /var/adm/cron/cron.deny files.
-
- - Obtain the fix from IBM Support.
-
- 1. To order from IBM call 1-800-237-5511 and ask
- that the fix be shipped. Outside the U.S., patches
- may be obtainedby contacting your local IBM
- representative.
-
- 2. If you are on the Internet, use anonymous ftp to obtain
- the fix from software.watson.ibm.com (129.34.139.5).
-
- Patch Filename Checksum
- AIX 3.2 pub/aix3/cronta.tar.Z 02324 154
-
- You must use binary mode to retrieve the patch.
-
- - Install the fix following the instructions in the README file.
-
- ---------------------------------------------------------------------------
- The CERT/CC would like to thank Fuat Baran of Advanced Network & Services,
- Inc., for bringing this security vulnerability to our attention and IBM for
- their 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.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 (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. *
- * *
- ****************************************************************************
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