The Intuity Audix voicemail system by default is maintained over port 23 (telnet) in a restricted command interface. If an attacker has a known account/password, they can circumvent this interface and get an unrestricted shell using rexec.
4fcde277b065ccb6ef5420098a7767fb530e514f5b5d5d99c34c266efcaab54a
This vulnerability is dedicated to my mother, who passed
away on April 7, 2003. Mom, may God be with you.
Avaya, a manufacturer of telecommunications products,
makes a voicemail system called Intuity Audix. This
system is based on a Novell licensed version of
Unixware v2.1.3 by SCO. The one used here comes with
remote management capabilities over IP.
This is not truly a 100% remote shell vulnerability,
due to the fact that the user must either know the "sa"
user password, or must be able to sniff the network
that the Intuity Audix machine is on. This will also
work with the "vm" user, or any other user who wishes
to authenticate over the network via telnet.
Initially, one might scan for open ports, or use an SNMP
browser, such as that commercially offered by Solarwinds,
and discover many open ports on the machine. Using SNMP,
the default community name of "public" is used. The services
of interest are snmp, http, exec, and telnet. Since telnet
is running, and the Avaya ASA GUI-based admin piece uses
port 23 as a default for the voicemail, we now know that
authentication is done in the clear. Using a network
analyzer that filters text (the one used here was the
Win32 port of dsniff), and being able to sniff the network
that the box is on, one would hopefully obtain a username
and password quickly.
Now using rexec (for purposes here, since the Win32 port of
dsniff was used, we will use command line rexec on Windows
2000 Professional) we type as follows:
rexec <ip address> -l(username) move /mtce/login/(username)/.profile
/mtce/login/(username)/.profile2
for example:
rexec 192.168.0.1 -lsa move /mtce/login/sa/.profile
/mtce/login/sa/.profile2
This will get us out of the restricted menu when telnetting into the box.
If the user is root or admin, the game is over. If the user is sa, vm, or
the ever guarded craft account (which oddly, does not have root
privileges),
then a vulnerable build of Apache server is on the machine. If your
version
is patched, or does not appear to be vulnerable, then there are many more
services running on this machine. root is just an exploit away.
Fixes:
Simple.... do not use SNMP v1, block access to SNMP, or just don't use it
at all. Do not use exec, telnet, or shell. Have the user authenticate over
SSH2. Patch the web server portion, even if it's just a DoS to the machine.
Since this is a proprietary system, Avaya will have to come up with a fix.
Make sure the shell is restricted, and there is no way to
exit the menu.
Greets,
Cushman
This is a shortened version of the original posting. The
full post can be seen at:
https://www.securitynerds.org/html/resources/research/audix.html