Date: Tue, 18 Jan 2005 13:03:18 -0800
From: please_reply_to_security@....com
To: security-announce@...t.sco.com, bugtraq@...urityfocus.com,
        full-disclosure@...ts.netsys.com
Subject: 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
______________________________________________________________________________


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
	----------------------------------------------------------------------
	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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