CERT Advisory CA-2001-05 Exploitation of snmpXdmid

Original release date: March 30, 2001
Source: CERT/CC

A complete revision history can be found at the end of this file.

Systems Affected

Any machine running Solaris 2.6, 7, or 8 with snmpXdmid installed and enabled. snmpXdmid is installed and enabled by default on these systems.

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

CERT/CC Vulnerability Note VU#648304 - Sun Solaris DMI to SNMP mapper daemon snmpXdmid contains buffer overflow

Affected sites have reported discovering the following things on compromised systems:

Evidence of extensive scanning for RPC services (port 111/{udp,tcp}) with explicit requests for the snmpXdmid service port prior to the exploit attempt
A core file from snmpXdmid on the / partition
An additional copy of inetd running (possibly using /tmp/bob as a configuration file)
A root-privileged telnet backdoor installed and listening on port 2766 (although any port could be used)
An SSH backdoor installed and listening on port 47018 (although any port could be used)
An IRC proxy installed as /var/lp/lpacct/lpacct and listening on port 6668
A sniffer installed as /usr/lib/lpset
Logs altered to hide evidence of the compromise
System binaries replaced by a rootkit installed in /dev/pts/01/ and /dev/pts/01/bin
(the versions of 'ls' and 'find' installed by the rootkit do not show these directories)
The contents of /dev/pts/01 may include

bin
crypt
idsol
patcher
su-backup
utime
bnclp
idrun
l3
pg
urklogin

The contents of /dev/pts/01/bin may include

du
find
ls
netstat
passwd
ping
psr
sparcv7
su

Note: Since 'ps' and 'netstat' are both replaced by the rootkit, they will not show these processes or open ports. However, you may find that '/usr/ucb/ps' is still intact, and will show the additional processes.

II. Impact

A local or remote user that is able to send packets to the snmpXdmi daemon on a system may gain root privileges.

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):

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

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.

Revision History

March 30, 2001: Initial release

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