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TUCoPS :: Unix :: General :: n-059.txt
Integer overflow in Sun RPC XDR library routines (CIAC N-059)

__________________________________________________________

The U.S. Department of Energy
Computer Incident Advisory Capability
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INFORMATION BULLETIN

Integer overflow in Sun RPC XDR library routines
[CERTŽ Advisory CA-2003-10]

March 19, 2003 21:00 GMT Number N-059
[REVISED 11 APR 2003]
[REVISED 16 Oct 2003]
______________________________________________________________________________
PROBLEM: There is an integer overflow in the xdrmem_getbytes() function
distributed as part of the Sun Microsystems XDR library. This
overflow can cause remotely exploitable buffer overflows in
multiple applications, leading to the execution of arbitrary
code.
AFFECTED Sun Microsystems network services library (libnsl)
SOFTWARE: BSD-derived libraries with XDR/RPC routines (libc)
GNU C library with sunrpc (glibc)
Hewlett Packard libc.1
DAMAGE: Exploiting this vulnerability could lead to denial of service,
possibly gaining root privileges, execution of arbitrary code,
or the disclosure of sensitive information.
SOLUTION: Check with your vendor for platform-specific patches or other
solutions.
______________________________________________________________________________
VULNERABILITY The risk is HIGH. Specific impacts reported include the ability
ASSESSMENT: to crash the rpcbind service and possibly execute arbitrary
code with root privileges. In addition, intruders may be able
to crash the MIT KRB5 kadmind or cause it to leak sensitive
information, such as secret keys.
______________________________________________________________________________
LINKS:
CIAC BULLETIN: http://www.ciac.org/ciac/bulletins/n-059.shtml
ORIGINAL BULLETIN: http://www.cert.org/advisories/CA-2003-10.html
Monitor the CERT Advisory for vendor updates.
ADDITIONAL LINKS: Red Hat updated glibc packages (not included in CERT's
Advisory).
https://rhn.redhat.com/errata/RHSA-2003-089.html
Visit Hewlett Packard Subscription Section for:
HPSBUX0303-252 SSRT2439 (rev. 7)
______________________________________________________________________________
REVISION HISTORY:
10/16/03 - added Hewlett Packards link for HPSBUX0303-252 SSRT2439 (rev. 7)

[***** Start CERTŽ Advisory CA-2003-10 *****]

CERTŽ Advisory CA-2003-10 Integer overflow in
Sun RPC XDR library routines

Original release date: March 19, 2003
Last revised: --
Source: CERT/CC

A complete revision history can be found at the end of this file.

Systems Affected

Applications using vulnerable implementations of SunRPC-derived XDR libraries,
which include

Sun Microsystems network services library (libnsl)
BSD-derived libraries with XDR/RPC routines (libc)
GNU C library with sunrpc (glibc)

Overview

There is an integer overflow in the xdrmem_getbytes() function distributed
as part of the Sun Microsystems XDR library. This overflow can cause
remotely exploitable buffer overflows in multiple applications, leading to
the execution of arbitrary code. Although the library was originally
distributed by Sun Microsystems, multiple vendors have included the vulnerable
code in their own implementations.

I. Description

XDR (external data representation) libraries are used to provide
platform-independent methods for sending data from one system process to another,
typically over a network connection. Such routines are commonly used in remote
procedure call (RPC) implementations to provide transparency to application
programmers who need to use common interfaces to interact with many different
types of systems. The xdrmem_getbytes() function in the XDR library provided by
Sun Microsystems contains an integer overflow that can lead to improperly sized
dynamic memory allocation. Depending on how and where the vulnerable
xdrmem_getbytes() function is used, subsequent problems like buffer overflows
may result.

Researchers at eEye Digital Security discovered this vulnerability and have
also published an advisory. This issue is currently being tracked as VU#516825
by the CERT/CC and as CAN-2003-0028 in the Common Vulnerabilities and Exposures
(CVE) dictionary. Note that this vulnerability is similar to, but distinct
from, VU#192995.

II. Impact

Because SunRPC-derived XDR libraries are used by a variety of vendors in a
variety of applications, this defect may lead to a number of security problems.
Exploiting this vulnerability will lead to denial of service, execution of
arbitrary code, or the disclosure of sensitive information.

Specific impacts reported include the ability to crash the rpcbind service and
possibly execute arbitrary code with root privileges. In addition, intruders may
be able to crash the MIT KRB5 kadmind or cause it to leak sensitive information,
such as secret keys.

III. Solution

Apply a patch from your vendor

Apply the appropriate patch or upgrade as specified by your vendor. See
Appendix A below and the Systems Affected section of VU#516825 for
further information.

Note that XDR libraries can be used by multiple applications on most systems.
It may be necessary to upgrade or apply multiple patches and then recompile
statically linked applications.

Applications that are statically linked must be recompiled using patched
libraries. Applications that are dynamically linked do not need to be recompiled;
however, running services need to be restarted in order to use the patched
libraries.

System administrators should consider the following process when addressing
this issue:

1.Patch or obtain updated XDR/RPC libraries.
2.Restart any dynamically linked services that make use of the XDR/RPC libraries.
3.Recompile any statically linked applications using the patched or updated XDR/RPC libraries.

Disable access to vulnerable services or applications

Until patches are available and can be applied, you may wish to disable
access to services or applications compiled with the vulnerable
xdrmem_getbytes() function.

As a best practice, the CERT/CC recommends disabling all services that are
not explicitly required.

Appendix A. - Vendor Information

This appendix contains information provided by vendors for this advisory.
As vendors report new information to the CERT/CC, we will update this section
and note the changes in our revision history. If a particular vendor is not
listed below, we have not received their comments.

Apple Computer, Inc.

Mac OS X and Mac OS X Server do not contain the vulnerabilities described
in this report.

Cray, Inc.

Cray Inc. may be vulnerable and has opened spr's 724153 and 724154 to
investigate.

Fujitsu

We are currently investigating how the vulnerability reported under VU#516825
affects the Fujitsu UXP/V O.S. We will update this statement as soon as new
information becomes available.

GNU glibc

Version 2.3.1 of the GNU C Library is vulnerable. Earlier versions are also
vulnerable. The following patches have been installed into the CVS sources,
and should appear in the next version of the GNU C Library. These patches are
also available from the following URLs:

http://sources.redhat.com/cgi-bin/cvsweb.cgi/libc/sunrpc/rpc/xdr.h.diff?r1=
1.26&r2=1.27&cvsroot=glibc

http://sources.redhat.com/cgi-bin/cvsweb.cgi/libc/sunrpc/xdr_mem.c.diff?r1=
1.13&r2=1.15&cvsroot=glibc

http://sources.redhat.com/cgi-bin/cvsweb.cgi/libc/sunrpc/xdr_rec.c.diff?r1=
1.26&r2=1.27&cvsroot=glibc

http://sources.redhat.com/cgi-bin/cvsweb.cgi/libc/sunrpc/xdr_sizeof.c.diff?r1=
1.5&r2=1.6&cvsroot=glibc

http://sources.redhat.com/cgi-bin/cvsweb.cgi/libc/sunrpc/xdr_stdio.c.diff?r1=
1.15&r2=1.16&cvsroot=glibc

2002-12-16 Roland McGrath

* sunrpc/xdr_mem.c (xdrmem_inline): Fix argument type.
* sunrpc/xdr_rec.c (xdrrec_inline): Likewise.
* sunrpc/xdr_stdio.c (xdrstdio_inline): Likewise.

2002-12-13 Paul Eggert

* sunrpc/rpc/xdr.h (struct XDR.xdr_ops.x_inline): 2nd arg
is now u_int, not int.
(struct XDR.x_handy): Now u_int, not int.
* sunrpc/xdr_mem.c: Include .
(xdrmem_getlong, xdrmem_putlong, xdrmem_getbytes, xdrmem_putbytes,
xdrmem_inline, xdrmem_getint32, xdrmem_putint32):
x_handy is now unsigned, not signed.
Do not decrement x_handy if no change is made.
(xdrmem_setpos): Check for int overflow.
* sunrpc/xdr_sizeof.c (x_inline): 2nd arg is now unsigned.
(xdr_sizeof): Remove cast that is now unnecessary, now that
x_handy is unsigned.

[ text of diffs available in the links included above --CERT/CC ]

Hewlett-Packard Company

RE: HP Case ID SSRT2439

At the time of writing this document, Hewlett Packard is currently
investigating the potential impact to HP's released Operating
System software products.

As further information becomes available HP will provide notice of the
availability of any necessary patches through standard security bulletin
announcements and be available from your normal HP Services support channel.

Hitachi

Hitachi's GR2000 gibabit router series - is NOT vulnerable.

IBM Corporation

The AIX operating system is vulnerable to the issues discussed in CERT
vulnerability note VU#516825 in releases 4.3.3, 5.1.0 and 5.2.0.

IBM provides the following official fixes:

APAR number for AIX 4.3.3: IY38524
APAR number for AIX 5.1.0: IY38434
APAR number for AIX 5.2.0: IY39231

Please contact your local IBM AIX support center for any assistance.

Ingrian Networks

Ingrian Networks products are not succeptable to the vulnerabilities in
VU#516825.

MIT Kerberos Development Team

It may be possible for a remote attacker to exploit an integer overflow in
xdrmem_getbytes() to crash the kadmind server process by a read segmentation
fault. For this to succeed, the kadmind process must be able to allocate
more than MAX_INT bytes of memory. This is believed to be unlikely, as most
installations are not likely to permit that the allocation of that much memory.

It may also be possible for a remote attacker to exploit this integer overflow
to obtain sensitive information, such as secret keys, from the kadmind process.
This is believed to be extremely unlikely, as there are unlikely to be ways for
the information, once improperly copied, of being returned to the attacker.
In addition, the above condition of the kadmind being able to allocate huge
amounts of memory must be satisfied.

Please see http://web.mit.edu/kerberos/www/advisories/MITKRB5-SA-2003-003-xdr.txt

This patch may also be found at:
http://web.mit.edu/kerberos/www/advisories/2003-003-xdr_patch.txt

The associated detached PGP signature is at:

http://web.mit.edu/kerberos/www/advisories/2003-003-xdr_patch.txt.asc

NEC Corporation

[Server Products] * EWS/UP 48 Series operating system - is NOT vulnerable.

NetBSD

The length types of the various xdr*_getbytes functions were made consistent
somewhere back in 1997 (all u_int), so we're not vulnerable in that area.

Network Appliance

NetApp products are not vulnerable to this issue.

Nokia

This issue has no relationship to the product we ship.

SGI

SGI acknowledges receiving CERT VU#516825 and is currently investigating.
This is being tracked as SGI Bug# 880925. No further information is available
at this time.

For the protection of all our customers, SGI does not disclose, discuss or
confirm vulnerabilities until a full investigation has occurred and any
necessary patch(es) or release streams are available for all vulnerable and
supported SGI operating systems. Until SGI has more definitive information to
provide, customers are encouraged to assume all security vulnerabilities as
exploitable and take appropriate steps according to local site security policies
and requirements. As further information becomes available, additional advisories
will be issued via the normal SGI security information distribution methods
including the wiretap mailing list on http://www.sgi.com/support/security/

Sun Microsystems

Solaris 2.6, 7, 8 and 9 are vulnerable to VU#516825.

Sun will be publishing a Sun Alert for the issue at the following
location shortly:
http://sunsolve.Sun.COM/pub-cgi/retrieve.pl?doc=fsalert/51884

The Sun Alert will be updated with the patch information as soon as the
patches are available.

At that time, the patches listed in the Sun Alert will be available from:
http://sunsolve.sun.com/securitypatch

Appendix B. - References

1.AD20030318.html - http://www.eeye.com/html/Research/Advisories/AD20030318.html
2.VU#192995 - http://www.kb.cert.org/vuls/id/192995
3.VU#516825 - http://www.kb.cert.org/vuls/id/516825
4.RFC1831 - http://www.ietf.org/rfc/rfc1831.txt
5.RFC1832 - http://www.ietf.org/rfc/rfc1832.txt

Thanks to Riley Hassell of eEye Digital Security for discovering and reporting
this vulnerability. Thanks also to Sun Microsystems for additional technical
details.

Authors: Chad Dougherty and Jeffrey Havrilla

This document is available from: http://www.cert.org/advisories/CA-2003-10.html

CERT/CC Contact Information

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Fax: +1 412-268-6989
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Conditions for use, disclaimers, and sponsorship information

Revision History

Mar 19, 2003: Initial release

[***** End CERTŽ Advisory CA-2003-10 *****]
_______________________________________________________________________________

CIAC wishes to acknowledge the contributions of CERT Coordination Center for the
information contained in this bulletin.
_______________________________________________________________________________

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