CERT^® Advisory CA-2001-05 Exploitation of snmpXdmid

The CERT/CC has received numerous reports indicating that a vulnerability in snmpXdmid is being actively exploited. Exploitation of this vulnerability allows an intruder to gain privileged (root) access to the system.

I. Description

The SNMP to DMI mapper daemon (snmpXdmid) translates Simple Network Management Protocol (SNMP) events to Desktop Management Interface (DMI) indications and vice-versa. Both protocols serve a similar purpose, and the translation daemon allows users to manage devices using either protocol. The snmpXdmi daemon registers itself with the snmpdx and dmid daemons, translating and forwarding requests from one daemon to the other.

snmpXdmid contains a buffer overflow in the code for translating DMI indications to SNMP events. This buffer overflow is exploitable by local or remote intruders to gain root privileges.

More information about this vulnerability can be found in

III. Solution

• Apply a patch from Sun when it is available

Sun has been notified of this issue and is actively working on patches to address the problem. This advisory will be updated when patches are available.

• Disable snmpXdmi

Until patches are available, sites that do not use both SNMP and DMI are stongly encouraged to disable snmpXdmid.

One way to accomplish this is to issue the following commands (as root):

1. Prevent the daemon from starting up upon reboot
   
   mv /etc/rc3.d/SXXdmi /etc/rc3.d/KXXdmi

   Killing the currently running daemon
   

   /etc/init.d/init.dmi stop

   Verify that the daemon is no longer active
   

   ps -ef | grep dmi

   As an additional measure, you may wish to make the daemon non-executable
   

   chmod 000 /usr/lib/dmi/snmpXdmid
• Restrict access to snmpXdmi and other RPC services

For sites that require the functionality of snmpXdmi or other RPC services, local IP filtering rules that prevent hosts other than localhost from connecting to the daemon may mitigate the risks associated with running the daemon. Sun RPC services are advertised on port 111/{tcp,udp}. The snmpXdmid RPC service id is 100249; use 'rpcinfo -p' to list local site port bindings:

# rpcinfo -p | grep 100249
  100249 1 udp 32785
  100249 1 tcp 32786

Note that site-specific port binding will vary.

Appendix A. - Vendor Information

Sun Microsystems

We can confirm that this affects all versions of Solaris that ship the SNMP to DMI mapper daemon, that is, Solaris 2.6, 7 and 8. To the best of my understanding from discussion with the engineering group working on this, for sites which do use DMI (dmispd) and the mapper (snmpXdmid), there are no workarounds.

The CERT/CC thanks Job de Haas (job@itsx.com) of ITSX BV Amsterdam, The Netherlands (http://www.itsx.com) for reporting this vulnerability to the CERT/CC.

This document was written by Brian B. King with significant contributions by Jeff Havrilla, and Cory F. Cohen.