-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Hi 3APA3A,

That's a good question, and here is my answer from the draft version of
an upcoming paper I'm working on:

"
Gaining SNMP write access to a device is already a compromise on its own
and usually considered a potential high risk security issue. Therefore,
one could argue that there is no point in launching a SNMP injection
attack when we can already change system settings via the SNMP write
community string. You might be wondering: why bother injecting a
HTML/JavaScript payload on the web console through SNMP when I can
change system parameters via SNMP alone?

In reality however, when a valid SNMP write community is identified, we
find that many OIDs cannot be changed due to read-only settings enforced
on that particular object. Instead, we are restricted to only being able
to change a limited number of OIDs.

What OIDs can be modified with a SNMP write community string depends on
two factors:

- - Specific vendor implementation of SNMP write permissions
- - SNMP RFCs

By being able to change a limited number of OIDs via a SNMP write
community string, the attacker might be able to DoS the device by
crippling its configuration settings or even deface some banners.
However, a serious attacker is ultimately interested in gaining full
access (admin/root) to the target device. Since identifying a valid SNMP
write community string might not be enough to accomplish such goal, it
makes sense to resort to SNMP injection.
"

Hope that helps.

Regards,
ap.

Vladimir '3APA3A' Dubrovin wrote:
> Dear ProCheckUp Research,
>
> What can you achieve with script injection you can not achieve with
> SNMP write access?
>
> --Thursday, October 9, 2008, 5:02:44 PM, you wrote to bugtraq (at) securityfocus (dot) com [email concealed]:
>
> PR> $ snmpset -v1 -c public 192.168.1.100 sysName.0 s
> '">><script>alert(1)</script>'
>
>

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.6 (GNU/Linux)
Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org

iD8DBQFI7xPVoR/Hvsj3i8sRAlIUAJ9ZWNliZ18Akibq0R7XuHSDMiPCsQCdGZi8
Hrr0hjnddyfu+8pUqKeJcXk=
=UIm8
-----END PGP SIGNATURE-----

[ reply ]