DOS-Attack against Gauntlet Firewall
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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:
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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:
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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:
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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