Denial of Service against Gauntlet-Firewall / SQL-Gateway

[Oliver Heinz <heinz@xxxxxxxx>]

DOS-Attack against Gauntlet Firewall
-------------------------------------
We found out a security-issue with the Oracle-Proxy (SQL-Gateway) of Gauntlet 
Firewall, Version 6 (manufactured by Secure Computing/NAI, serversrunning 
Solaris 8, newest Patches installed). 

Abstract:
---------
Sending subsequent requests with invalid data to the firewalls SQL-gateway 
results in an immediate crash. The firewall won't accept any further 
connections on any SQL-gw that is defined in the rule base.
Secure Computing as vendor of Gauntlet could reproduce the DOS, patches or bug 
fixes are not yet available.

Description:
-------------
We tried to monitor the firewall's sql-gw with our own monitoring-system to 
make sure that we notice if it does not run. Some seconds later, the sql-gw 
crashed and we were no longer able to connect the port.

Further investigation of the problem showed that the sql-gw-process can easily 
be crashed on any Gauntlet-Firewall by simply connecting to it:

Try the following (_very_ basic)script, use your firewall's IP instead of 
aaa.bbb.ccc.ddd, running sql-gw at the standard port 1521: 

        for a in 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
        do
                telnet aaa.bbb.ccc.ddd 1521
        done 

You will see that the last try to connect (#17) results in "Connection refused" 
and the process of "sql-gw" is no longer running on the firewall. ==> A DOS 
against Gauntlet is very easy.

This is especially unpleasant, as Gauntlet is one of the few major 
firewall-products that provide true application level security _and_ do have a 
dedicated application-proxy for SQL (sql-net 1 + 2). 
In fact, many companies use Gauntlet especially to protect database-servers.

Solution/ Patches:
------------------
Secure Computing (www.securecomputing.com), the manufacturer of 
Gauntlet-Firewall, has been informed by arago about the issue in August 2003 
and has been able to reproduce the problem. 
Unfortunately, they have not yet managed to bring out a security-patch :-(
The only current solution they give is to use "plug-gws" instead of the 
"sql-gws", which obviously weakens security _and_ performance a lot, as you 
lose application-level security!   

Regards, Oliver Heinz


 
  ---------------------------------------------------------------------
 | arago,                   | Oliver Heinz                             |
 | Institut fuer komplexes  | Bereichsleiter Systembetrieb & Security  |
 | Datenmanagement AG       | eMail: heinz@xxxxxxxx                    |
 | Am Niddatal 3            |                                          |
 | 60488 Frankfurt am Main  | http://www.arago.de/                     |
 |                          | PGP-Fingerprint: a5de d4b4 46b3 4d8b 2646|
 |                          |                  d4d0 e5fd d842 cc4e 7315|
  ---------------------------------------------------------------------