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The crontab program is running setuser-id root and invokes the editor specified in the EDITOR environment variable, usually vi. If crontab discovers that the format of the edited file is incorrect, it executes the editor again but fails to drop its root privileges before. Therefore it is possible to execute arbitrary commands as root. Sebastian Krahmer has found the bug. It has been fixed by properly dropping the privileges before executing the editor.
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-----BEGIN PGP SIGNED MESSAGE-----
______________________________________________________________________________
SuSE Security Announcement
Package: cron-3.0.1-296
Announcement-ID: SuSE-SA:2001:17
Date: Tuesday, May 15th, 2001 14:30:00 CEST
Affected SuSE versions: 7.1
Vulnerability Type: local privilege escalation
Severity (1-10): 7
SuSE default package: yes
Other affected systems: All UN*X systems using this package
Content of this advisory:
1) security vulnerability resolved: crontab
problem description, discussion, solution and upgrade information
2) pending vulnerabilities, solutions, workarounds
3) standard appendix (further information)
______________________________________________________________________________
1) problem description, brief discussion, solution, upgrade information
The crontab program is running setuser-id root and invokes the editor
specified in the EDITOR environment variable, usually vi.
If crontab discovers that the format of the edited file is incorrect, it
executes the editor again but fails to drop its root privileges before.
Therefore it is possible to execute arbitrary commands as root.
Sebastian Krahmer has found the bug. It has been fixed by properly dropping
the privileges before executing the editor.
A possible temporary workaround is to remove the suid bit of the
/usr/bin/crontab program: chmod -s /usr/bin/crontab.
If you change the mode, you should also do so in the files
/etc/permissions*. A permanent solution for the problem is to update the
cron package from our ftp server.
Download the update package from locations desribed below and install
the package with the command `rpm -Uhv file.rpm'. The md5sum for each
file is in the line below. You can verify the integrity of the rpm
files using the command
`rpm --checksig --nogpg file.rpm',
independently from the md5 signatures below.
i386 Intel Platform:
SuSE-7.1
ftp://ftp.suse.com/pub/suse/i386/update/7.1/a1/cron-3.0.1-297.i386.rpm
b51f3331fff5dac8474a51a1e7d22454
source rpm:
ftp://ftp.suse.com/pub/suse/i386/update/7.1/zq1/cron-3.0.1-297.src.rpm
495f7f5df30d28a0c6b078a9773fc799
Sparc Platform:
SuSE-7.1
ftp://ftp.suse.com/pub/suse/sparc/update/7.1/a1/cron-3.0.1-316.sparc.rpm
4db292d0276badc0ae58fd6aeaab64c0
source rpm:
ftp://ftp.suse.com/pub/suse/sparc/update/7.1/zq1/cron-3.0.1-316.src.rpm
16facdbbce03d43fa05d540b810d8636
AXP Alpha Platform:
The SuSE-7.1 AXP-Alpha Edition does not suffer from this problem.
PPC Power PC Platform:
SuSE-7.1
ftp://ftp.suse.com/pub/suse/ppc/update/7.1/a1/cron-3.0.1-295.ppc.rpm
589e8575bbbee29a07319f5c5ada9bcc
source rpm:
ftp://ftp.suse.com/pub/suse/ppc/update/7.1/zq1/cron-3.0.1-295.src.rpm
ff747e2aee85a53e3a30827b33383a7d
______________________________________________________________________________
2) Pending vulnerabilities in SuSE Distributions and Workarounds:
- The man program running setuser-id 'man' suffers from format string and
bufferoverflow bugs. Updates are currently being built.
______________________________________________________________________________
3) standard appendix:
SuSE runs two security mailing lists to which any interested party may
subscribe:
suse-security@suse.com
- general/linux/SuSE security discussion.
All SuSE security announcements are sent to this list.
To subscribe, send an email to
<suse-security-subscribe@suse.com>.
suse-security-announce@suse.com
- SuSE's announce-only mailing list.
Only SuSE's security annoucements are sent to this list.
To subscribe, send an email to
<suse-security-announce-subscribe@suse.com>.
For general information or the frequently asked questions (faq)
send mail to:
<suse-security-info@suse.com> or
<suse-security-faq@suse.com> respectively.
===============================================
SuSE's security contact is <security@suse.com>.
===============================================
Regards,
Sebastian Krahmer
______________________________________________________________________________
The information in this advisory may be distributed or reproduced,
provided that the advisory is not modified in any way.
SuSE GmbH makes no warranties of any kind whatsoever with respect
to the information contained in this security advisory.
Type Bits/KeyID Date User ID
pub 2048/3D25D3D9 1999/03/06 SuSE Security Team <security@suse.de>
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This archive was generated by hypermail 2.1.0
: Mon Jun 04 2001 - 18:25:16 PDT
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