[28141] in bugtraq
Security Update: [CSSA-2002-SCO.43] UnixWare 7.1.1 Open UNIX 8.0.0 : closed file descriptor race vulnerability
daemon@ATHENA.MIT.EDU (security@caldera.com)
Mon Dec 9 17:46:04 2002
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Date: Mon, 9 Dec 2002 13:41:12 -0800
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To: bugtraq@securityfocus.com announce@lists.caldera.com scoannmod@xenitec.=
on.ca full-disclosure@lists.netsys.com
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SCO Security Advisory
Subject: UnixWare 7.1.1 Open UNIX 8.0.0 : closed file descriptor race vuln=
erability
Advisory number: CSSA-2002-SCO.43
Issue date: 2002 December 09
Cross reference:
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1. Problem Description
On current OpenBSD systems, any local user (being or not in
the wheel group) can fill the kernel file descriptors table,
leading to a denial of service. Because of a flaw in the way
the kernel checks closed file descriptors 0-2 when running a
setuid program, it is possible to combine these bugs and earn
root access by winning a race condition.
Since UnixWare does not have a global kernel file descriptors
table (it has per-process dynamic file descriptors table), it
is not prone to the denial of service attack and the race
condition resulting in root exploit.
The second problem, however, does exist - closing file
descriptors 0, 1 and/or 2 before exec'ing a setuid program
can make this program open files under these fds, which have
special meanings for libc (stdin/out/err). Reading or writing
to root-owned files can be made possible, since
stdXX=3D=3Dopened_file.
The fix done for BSD is to check (in the kernel) before
exec'ing a set[ug]id program if fd 0, 1 and 2 are closed, and
if so redirect them to /dev/null. We have done the same fix
for UnixWare.
This fix will only kick in when an unprivileged process
execs a set[ug]id program.
=20
2. Vulnerable Supported Versions
System Binaries
----------------------------------------------------------------------
UnixWare 7.1.1 /etc/conf/pack.d/proc/Driver_atup.o
/etc/conf/pack.d/proc/Driver_mp.o
Open UNIX 8.0.0 /etc/conf/pack.d/proc/Driver_atup.o
/etc/conf/pack.d/proc/Driver_mp.o
3. Solution
The proper solution is to install the latest packages.
4. UnixWare 7.1.1
4.1 Location of Fixed Binaries
ftp://ftp.sco.com/pub/updates/OpenUNIX/CSSA-2002-SCO.43
4.2 Verification
MD5 (erg712059.711.pkg.Z) =3D 1545beb0d12890de701e129de54bf7b6
md5 is available for download from
ftp://ftp.sco.com/pub/security/tools
4.3 Installing Fixed Binaries
*** NOTE: THE UW711M2 SUPPLEMENT MUST BE INSTALLED PRIOR TO
APPLYING THIS UPDATE.
Upgrade the affected binaries with the following sequence:
Download erg712059.711.pkg.Z to the /var/spool/pkg directory
# uncompress /var/spool/pkg/erg712059.711.pkg.Z
# pkgadd -d /var/spool/pkg/erg712059.711.pkg
5. Open UNIX 8.0.0
5.1 Location of Fixed Binaries
ftp://ftp.sco.com/pub/updates/OpenUNIX/CSSA-2002-SCO.43
5.2 Verification
MD5 (erg712059.ou8.pkg.Z) =3D 9291ab96576e48b55e981190480855ca
md5 is available for download from
ftp://ftp.sco.com/pub/security/tools
5.3 Installing Fixed Binaries
*** NOTE: THE OU800PK4 SUPPLEMENT MUST BE INSTALLED PRIOR TO
APPLYING THIS UPDATE.
Upgrade the affected binaries with the following sequence:
Download erg712059.ou8.pkg.Z to the /var/spool/pkg directory
# uncompress /var/spool/pkg/erg712059.ou8.pkg.Z
# pkgadd -d /var/spool/pkg/erg712059.ou8.pkg
6. References
Specific references for this advisory:
http://cve.mitre.org/cgi-bin/cvename.cgi?name=3DCAN-2002-0766
SCO security resources:
http://www.sco.com/support/security/index.html
This security fix closes SCO incidents sr865063, fz526562,
erg712059.
7. 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.
8. Acknowledgements
FozZy <fozzy@dmpfrance.com>, et al. discovered and researched
this vulnerability.
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