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MS Security Patch Blocks Net Access For ZoneAlarm Users
An anonymous reader writes "Users of Check Point ZoneAlarm security products, including the extremely popular, free-of-charge software firewall, have discovered that a Microsoft security update released on Tuesday has blocked their internet access. The firewall manufacturer is 'investigating the issue,' and so far the workaround seems to be to uninstall the recent DNS spoofing vulnerability fix MS08-037 (KB951748), and not reinstall it until Microsoft or Check Point have come up with updated versions of their products."
Kevin Smith on Prince
Set Zonealarm's security level to "medium".
If you're reading this article from a machine in question, you're not broken.
Now please don't call me asking if it's something you should worry about.
"It is a miracle that curiosity survives formal education." -Albert Einstein
This patch was not designed to patch a Microsoft flaw, but instead a vulnerability in nearly all implementations of DNS. So far over 100 vendors have patched their products and coordinated the release of this workaround. If zone alarm is broken because of this change they need to adjust their product to work with this change, not the other way around.
I've taken this snippet from: http://isc.sans.org/diary.html?storyid=4687 which explains things in a little more detail. Full details won't be disclosed until Blackhat in vegas this August.
The root cause is a fundamental, well known, weakness in the DNS protocol. DNS uses UDP, a stateless protocol. A DNS server will send a request in a single UDP packet, then wait for a response to come back. In order to match request and response, a number of parameters are checked:
who sent the response? Was it the DNS server we sent the request to?
for this particular response, do we have an outstanding request?
each request uses a unique and random query ID. The response has to use the same query ID.
The response has to be sent to the same port from which the request was sent.
Only if all this matches, the response is accepted. The first valid response wins. If an attacker is able to guess the query id and the source port, the attacker is able to send a fake response, which will be cached by the DNS server.
Remember that you are unique, just like everybody else.
Why not take this time to try out something new?
Why are we assuming that this is a defect in the Microsoft patch, rather than a defect in the security software? I think it's much more likely that the software firewall application (which tend to be pretty skeevy in general, see Norton Internet Security) is inappropriately blocking access than that Microsoft screwed up the patch. From my (admittedly vague) understanding of the issue, I'm guessing that the firewall software whitelists outgoing UDP requests from port 53, and the new randomized ports are being blocked, preventing DNS queries from succeeding. I know blaming Microsoft is fun, but blaming even crappier software vendors is more fun :)
We have a Cisco ASA at work for a large enterprise and about 2 hours after I applied the patch to our DNS servers running BIND, they the ASA device blackholed the DNS servers. Wasn't a fun day really.
Ahh the great security blanket called the software firewall. I like to use the following analogy in regards to them. Having a software firewall on your computer is like having a security guard in your bathroom. If something gets to the guard it's too late, your network is already compromised.
I work for an ISP in Tacoma WA, and Software firewalls cause many more problems then they solve. I don't care which company makes it.
If you are really concerned about security then you will have a dedicated hardware firewall. These are inexpensive and common, even built into most SOHO routers.
So I know there will probably be flames, but if you write software firewalls, remember that the overwhelming majority of people who use them don't usually know they have one, and just ignore those little messages and click allow on everything until they actually read something and say "msimn.exe, what's that? I'm gonna block it!" And then they call me because their e-mail doesn't work.
I'm a happy pessimist. I expect and prepare for the worst, when it doesn't happen I am pleasantly surprised.
...or instead of complaining to Microsoft, you can disable ZoneAlarm and enjoy having your connection work again. Cheap firewalls failing to perform exactly how you'd like them to is an old, old story.
Given the ridiculous profusion of budget 'security' software swarming around, it hardly seems fair to lay the blame on M$ when ZoneAlarm is the only program that this patch appears to conflict with.
Of course, if ZoneAlarm wasn't proprietary, we could go see where they screwed up. Maybe you should go harass them for being closed-source instead?
"We have to go forth and crush every world view that doesn't believe in tolerance and free speech." - David Brin
And what do Slashdot readers have to say? In about equal numbers:
OK geniuses. What, realistically, is the industry supposed to do in order to stop doing this sort of thing?
I don't know what the answer is. If I did, I'd be lining up staffing, capital, etc. But I'm 100% sure that it is not:
You can't see ANYTHING from a car, You've got to get out of the goddamned contraption and walk...Edward Abbey
Don't worry. Removing the patch was easy once I knew that was what needed to be done. Just go to Add/Remove Programs, check the box for "Show updates", scroll down to KB951748, click the Remove button, and reboot (again).
The may be a big headache for somebody at an ISP who needs to help out users, but as somebody who uses ZoneAlarm, I find it to be very useful.
I've got an actual firewall in my router, but that only protects me from what comes in. And I run Linux, so that counters most other random garbage. But, on occasion, I use Windows and ZoneAlarm is very handy because it alerts me when any program is trying to send data out.
*This* is where software firewalls in Windows shine. So many programs in Windows phone home or access the Internet for completely unknown reasons. So, I block it. If it breaks and I really need that particular program, I can unblock it. It's hard to measure how much this really helps, and, of course, I'm sure there are ways to transmit in Windows without the firewall knowing about it. Still, it's nice to be able to say apps X and Y, you get to access the Net. Everybody else has to ask first.
Elrond, Duke of URL
"This is the most fun I've had without being drenched in the blood of my enemies!"-Sam&Max