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Marcel-Jan
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TNS Poisoning
« on: May 29th, 2012, 2:50pm »
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You might have heared about the latest Oracle security bug, the TNS Poisoning bug. It's a bug that exists since Oracle 8i.
 
What's the problem?
With this bug it is possible to register a listener on a remote location on an Oracle instance. The problem with that is that you can listen in on Oracle network traffic.
 
Oracle made it possible to add remote listeners to an instance for Oracle Real Application Clusters (RAC). Nowadays it is best practice in RAC systems to define (remote) so called SCAN listeners.
 
How big is the problem?
I don't know the CVSS score (the score that measures how severe a security bug is). Probably it's a pretty high CVSS score.
 
I've got questions of several people that never install Critical Patch Updates. Do that first, before you worry about this bug.
 
Why isn't the patch for this bug part of a Critical Patch Update?
The next Critical Patch Update will be available only in July. Very likely this bug will be solved in that CPU.
 
What is the solution at this moment?
There are three possible solutions: two for single instance databases (the usual setup) and one for RAC databases. See Oracle support note 1453883.1 for single instance and note 1340831.1 for RAC databases.
 
The short description: one of the solutions for single instance databases is a patch for bug 12880299. You can search patches on bugs in support.oracle.com. You’ll find it that way. The other single instance solution is changing the protocol with what de listener communicates with the database from TCP to IPC.
 
(I believe you also can turn of dynamic listener registration with a parameter. From then on you have to register a listener to the database manually.)
 
The RAC solution has to work around the fact that you actually want remote listeners to connect to a database. Remote SCAN listeners have become a best practice in high availability solutions. So Oracle had to think up a solution for that as well. And the solution is to protect listener-database communication with SSL. This solution is actually part of the Advanced Security option, but Oracle has allowed customers to use this particular Advanced Security functionality without having to pay for the license (if you don't have that license). If you implement any other functionality of the Oracle Advanced Security Option, you will have to pay for the license.
 
So if I choose the IPC solution, I don't need the patch?
It seems that way. I haven't tried it myself.
 
Why isn't there a patch for bug 12880299 on Windows?
Actually, there is: there is a patch for 11.1.0.7 and 11.2.0.3 on Windows (32 and 64 bit). It was issued later than the patches for Linux.
 
What's the impact of these solutions?
As far as I know: you have to restart one or more listeners.
« Last Edit: May 29th, 2012, 2:52pm by Marcel-Jan » IP Logged
laurentschneider
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Re: TNS Poisoning
« Reply #1 on: Jun 5th, 2012, 12:38pm »
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Hi,  
 
Quote:
I don't know the CVSS score (the score that measures how severe a security bug is). Probably it's a pretty high CVSS score.

7.5 according to https://blogs.oracle.com/security/entry/security_alert_for_cve_2012
 
Quote:
Very likely this bug will be solved in that CPU.

More likely will be fixed in next release
 
Quote:
(I believe you also can turn of dynamic listener registration with a parameter. From then on you have to register a listener to the database manually.)

Indeed, DYNAMIC_REGISTRATION_LISTENER=off sounds wise. You will then be back to the good old SID_LIST_LISTENER days... Probably the best protection  
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Marcel-Jan
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Re: TNS Poisoning
« Reply #2 on: Jun 6th, 2012, 2:21pm »
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I've been reading a lot of Oracle CPU assessments by TeamSHATTER and I've learned that Oracle's CVSS scores can be lower due to their Partial+ scoring system. If not Oracle, the CVSS score would often be 9 or 10.
 
Quote:
Indeed, DYNAMIC_REGISTRATION_LISTENER=off sounds wise. You will then be back to the good old SID_LIST_LISTENER days... Probably the best protection

If this is the way things are going (less userfriendly is more secure) we'll be dealing with maxextent in no time.  Grin
« Last Edit: Jun 6th, 2012, 2:50pm by Marcel-Jan » IP Logged
Pete Finnigan
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Re: TNS Poisoning
« Reply #3 on: Sep 3rd, 2012, 4:15pm »
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Thanks Marcel-Jan for this post; sorry for the delayed reply. This has scoring being lowered has always been the case. I think it was Steve Kost who wrote about the scores and the calculations some years ago.
 
cheers
 
Pete
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Re: TNS Poisoning
« Reply #4 on: Sep 3rd, 2012, 5:07pm »
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Bouncing on your answer, I must said that disabling dynamic registration proved difficult, whenever you use standby, apex, xml and family, you need workarounds and lose on flexibility
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Re: TNS Poisoning
« Reply #5 on: Sep 3rd, 2012, 7:48pm »
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Thanks Laurent, for your feedback on this specifically for APEX, standby, XML etc; what workarounds did yout use and what was the trade off?
 
Kind regards
 
Pete
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Re: TNS Poisoning
« Reply #6 on: Sep 3rd, 2012, 8:11pm »
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actually for standby it is all benefit, you just need to edit your  StaticConnectIdentifier with dgmgrl to use sid instead of service_name, which also permits smoother switchover from command line
 
for apex it is not a requirment to use the apex listener, you could use an apache  
 
for xmldb my workaround was to not use xmldb  Tongue Maybe other workaround exists
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Re: TNS Poisoning
« Reply #7 on: Sep 4th, 2012, 8:27am »
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Hi Laurent,
 
Thanks for the update, i hope it is useful for those who have not worked to solve this issue yet.
 
Thanks
 
Pete
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