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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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