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CERT Advisory CA-2000-17

Hash: SHA1

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

   Original release date: August 18, 2000
   Source: CERT/CC
   A complete revision history is at the end of this file.
Systems Affected

     * Systems running the rpc.statd service

   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
><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>^
<88>F'<88>F*<83> <88>F<89>F+,
/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
   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
   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
   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
   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

   At the time of writing this document, Compaq is currently
   investigating the potential impact to Compaq's rpc.statd service.
   Initial tests indicate it is not a potential vulnerability for Compaq
   supplied software.
   As further information becomes available Compaq will provide notice
   the completion/availability of any necessary patches through AES
   services (DIA, DSNlink FLASH and posted to the Services WEB page) and
   be available from your normal Compaq Services Support channel.

   FreeBSD is not vulnerable to this problem.

   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
   for the format argument.

   *Linux* systems running the rpc.statd service!
   This affects noone else!
Silicon Graphics, Inc.

   IRIX rpc.statd is not vulnerable to this security issue.
   Authors: John Shaffer, Brian King
   This document is available from:
CERT/CC Contact Information

   Email: cert at
          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
   CERT personnel answer the hotline 08:00-20:00 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
Getting security information

   CERT publications and other security information are available from
   our web site
   To be added to our mailing list for advisories and bulletins, send
   email to cert-advisory-request at and include SUBSCRIBE
   your-email-address in the subject of your message.
   * "CERT" and "CERT Coordination Center" are registered in the U.S.
   Patent and Trademark Office.
   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
   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
   August 18, 2000:  Initial release

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