UnixWare 7.1.4 UnixWare 7.1.3 UnixWare 7.1.1 : chroot A known exploit can break a chroot prison.
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SCO Security Advisory
Subject: UnixWare 7.1.4 UnixWare 7.1.3 UnixWare 7.1.1 : chroot A
known exploit can break a chroot prison.
Advisory number: SCOSA-2005.2
Issue date: 2005 January 14
Cross reference: sr887824 fz528555 erg712509 CAN-2004-1124
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1. Problem Description
chroot() is a system call that is often used to provide an
additional layer of security when untrusted programs are
run. The call to chroot() is normally used to ensure that
code run after it can only access files at or below a given
directory.
Originally, chroot() was used to test systems software in
a safe environment. It is now generally used to lock users
into an area of the file system so that they can not look
at or affect the important parts of the system they are on.
Several programs use chroot jails to ensure that even if
you break into the process's address space, you can't do
anything harmful to the whole system. If chroot() can be
broken then this precaution is broken.
A known exploit can break a chroot prison.
The Common Vulnerabilities and Exposures project
(cve.mitre.org) has assigned the name CAN-2004-1124 to t
his issue.
A new file system tunable, CHROOT_SECURITY is provided to
protect against the known exploit for escaping from a chroot
prison. The new tunable is described in /etc/conf/dtune.d/fs
and defined in /etc/conf/mtune.d/fs. Protection is provided
by the default value of 1 but traditional behavior may be
obtained by resetting CHROOT_SECURITY to 0.
chroot() is a good way to increase the security of the
software provided that secure programming guidelines are
utilized and chroot() system call limitations are taken
into account. Chrooting will prevent an attacker from
reading files outside the chroot jail and will prevent
many local UNIX attacks (such as SUID abuse and /tmp
race conditions).
The number of ways that root user can break out of chroot
is huge. If there is no root user defined within the
chroot environment, no SUID binaries, no devices, and
the daemon itself dropped root privileges right after
calling chroot() call breaking out of chroot appears to
be impossible.
2. Vulnerable Supported Versions
System Binaries
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UnixWare 7.1.4 /etc/conf/pack.d/namefs/Driver_atup.o
/etc/conf/pack.d/namefs/Driver_mp.o
/usr/include/sys/vfs.h
UnixWare 7.1.3 See Maintainance pack 4
UnixWare 7.1.1 See Maintainance pack 5
3. Solution
The proper solution is to install the latest packages.
4. UnixWare 7.1.4
4.1 Location of Fixed Binaries
ftp://ftp.sco.com/pub/updates/UnixWare/SCOSA-2005.2
4.2 Verification
MD5 (erg712629c.pkg.Z) = 480ecc98f9c918a3b35082c1bef2aa44
md5 is available for download from
ftp://ftp.sco.com/pub/security/tools
4.3 Installing Fixed Binaries
Upgrade the affected binaries with the following sequence:
Download erg712629c.pkg.Z to the /var/spool/pkg directory
# uncompress /var/spool/pkg/erg712629c.pkg.Z
# pkgadd -d /var/spool/pkg/erg712629c.pkg
5. UnixWare 7.1.3
5.1 Location of Fixed Binaries
The fixes are available in SCO UnixWare Release 7.1.3
Maintenance Pack 4 or later. See
ftp://ftp.sco.com/pub/unixware7/713/mp/mp4/uw713mp4.txt
or
ftp://ftp.sco.com/pub/unixware7/713/mp/mp4/uw713mp4.html
5.2 Verification
MD5 (uw713mp4.image) = 7eb9e20ed6a6d9ed1ab7335323bf25d1
md5 is available for download from
ftp://ftp.sco.com/pub/security/tools
5.3 Installing Fixed Binaries
Upgrade the affected binaries with the following sequence:
Download uw713mp4.image to the /var/spool/pkg directory
# pkgadd -d /var/spool/pkg/uw713mp4.image
6. UnixWare 7.1.1
6.1 Location of Fixed Binaries
The fixes are available in SCO UnixWare Release 7.1.1
Maintenance Pack 5 or later. See
ftp://ftp.sco.com/pub/unixware7/uw711pk/uw711mp5.txt
and
ftp://ftp.sco.com/pub/unixware7/uw711pk/uw711mp5_errata.txt
6.2 Verification
MD5 (uw711mp5.cpio.Z) = 50bd66b7d57b2025da9dca4010d0ab1a
md5 is available for download from
ftp://ftp.sco.com/pub/security/tools
6.3 Installing Fixed Binaries
See uw711mp5.txt and uw711mp5_errata.txt for install instructions.
7. References
Specific references for this advisory:
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2004-1124
http://www.packetfactory.net/projects/libexploit/
http://www.bpfh.net/simes/computing/chroot-break.html
http://www.linuxsecurity.com/content/view/117632/49/
SCO security resources:
http://www.sco.com/support/security/index.html
SCO security advisories via email
http://www.sco.com/support/forums/security.html
This security fix closes SCO incidents sr887824 fz528555
erg712509.
8. Disclaimer
SCO is not responsible for the misuse of any of the information
we provide on this website and/or through our security
advisories. Our advisories are a service to our customers
intended to promote secure installation and use of SCO
products.
9. Acknowledgments
SCO would like to thank Simon Roses Femerling
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