CERT® Advisory CA-1992-10 AIX crontab VulnerabilityOriginal issue date: May 26, 1992
Last revised: September 19, 1997
Attached copyright statement
A complete revision history is at the end of this file.
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 21:22:40If your crontab contains older modules than the above output indicates, we suggest that you install the fix.
I. DescriptionThe distributed version of /usr/bin/crontab contains a security vulnerability.
II. ImpactLocal users can gain unauthorized root access to the system.
III. SolutionThe 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.
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.
This document is available from: http://www.cert.org/advisories/CA-1992-10.html
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Copyright 1992 Carnegie Mellon University.
September 19,1997 Attached copyright statement