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Secret Repairs Preceded TCP Flaw Release
efranco cuts and pastes: "Only the math had changed. But the emergence of a workable exploit for an old TCP security hole prompted a secret initiative to fix the Internet, giving network operators a week to secure vulnerable routers. The clandestine repair effort livened an already intense period for security pros already juggling a bevy of Windows security patches." We ran a story on a this a few days ago.
is here as posted from an article on the register.
I think we're gonna see a lot more of this. If you release information before you fix it these days you're just inviting people to test your shiny new vulnerability ;-)
we see things not as as they are, but as we are.
-- anais nin
When will I be able to download a fixed version?
The best kind!
"What are you doing?"
"Can't tell you."
"When will you be done?"
"Can't say."
"Is there anything you can tell me?"
"This will save your life."
"Really?"
"No."
Any user without the technical competence to inspect and repair TCP/IP packets on the fly should not be allowed to use the Internet. Such vulnerabilities only exist because people too lazy and ignorant to download the patches for their Cisco routers!
Ceci n'est pas une signature
Yesterday was 1998? Whew, I thought it was 2004 and 6 years of my life were wasted
This was reported three days ago by another reader.
Yawn.
bash: rtfm: command not found
"We ran a story on a this a few days ago." What's a "this" ?
while true ; do echo this is my sig; done
Does anyone know if this affects IPv6? I wonder if this situation could somehow be leveraged to promote it...
It's the one with the red "S" on its chest . . .
Ba dum bump.
I'm not tense. I'm just terribly, terribly, alert.
From the article:
"The actual threat to the Internet is really small right now," Watson said on Wednesday. "You could have isolated attacks against small networks, but they would most likely be able to recover quickly."
"Teleporting Rodents with D-Cell Battery Displacement" theory -- IgnoramusMaximus (692000)
It's effective when used as the external skin of a layered approach.
Some would say it should be disposed of entirely, in favor of the bugtraq, etc. totally-open approach.
That approach is IMO foolish. Why throw away a useful layer of security? In 1992 it was debatable; the interim years have shown without a doubt that the totally-open approach produces more script kiddies than it does patched systems.
Yes, I would prefer to know immediately if I was vulnerable. However, the vast majority of defense is against script kiddies who wait to have exploits handed to them so they can copy and paste some malicious code together to prove what "hackers" they are. Why should we tell them before there's a patch? I dunno. Hopefully someone smarter than me is working on it.
Yeah, I guess I'm funny like that.
Usually people take it upon themselves to notify vendors of bugs and give them time to work on patches or workarounds before releasing the information. For anyone that reads full disclosure lists such as bugtraq this is very commoon. Also, when the bug affects key internet infrastructure, the admins of big isps/colos/routers are informed and given time to patch. This is good for the internet and good for vulnerability researches instead of looking like malicious people who just want to destroy the internet.
:(){
It's an exploit that could affect the core routers of the internet. This one could technical reset 100% of webtraffic going through a particular router, in theory. Of course, this won't make a lick of difference to your average webserver, as they handle many connection resets a day. It would only affect those sites that traffic is so large that if all connections were reset it would cause a flood of re-connects thereby socking bandwidth. This is more directed at always up type connections, such as Telnet, SSH (as the article points out), credit card traffic, etc.. HTTP is constantly dropping and connecting anyways..
Mod +5 Drunk
Dilbert is in the Boss's office.
Dilbert: I discovered a hole in our internet security.
Boss: What?!!
Boss: Good grief, man! How could you put a hole in our internet?
Dilbert, angry: I didn't PUT it there, I FOUND it.. and it's not...
Boss: It's your job to fix that hole. I want you to work 24-7!
Dilbert: Actually, that's NOT my job. But I'll inform our network management group.
Boss, yelling: PASSING THE BUCK!!! YOU'RE A BUCK PASSER!!!
Dilbert: Forget it! There's no hole! It got better!
Boss: That's more like it.
Last panel, the boss is sitting alone smiling.
Boss thinks: I fixed the internet.
Is this just a case of paranoia reigning supreme? From what I understand of this problem (And it is very possible that I don't know all the details) it only poses a risk under a very specific set of circumstances and that this set of circumstances is very common. Are we becoming ParaNET?
The Erogenous Zone
Many networks used home-grown routers based on Linux, FreeBSC, user-space TCP/Firewall/VPN implementations, or even windows. However, the vendor list only includes commercial router manufacturers. This seems to me like a serious problem waiting to happen; the would-be exploiter now know what systems would remain unpatched for a long time.
The whole TCP window thing seems entirely obvious to me, i just hadn't realised that windows were sufficiently big to be guessed. As we start to see faster and faster transfers we'll need larger and larger windows and this will just get easier.
However I cant see why BGP needs to implement a large window - in fact in a device which needs to run as fast as possible it's surely disadvantageous.
I've seen TCP RST attacks in the mid nineties actually used on IRC - only the application of the exploit to bgp is new.
There are people who use Windows boxes as routers
... Now right click, select BGP... Click peer...
... That's correct sir... it's probably not a good idea to run IIS on your core router...
Now that's scary...
Imagine the techsupport on that mess...
Why worry? Each of us is wearing an unlicensed "nucular" accelerator on his back.
Sig changed for readability by G.W.
What dinkleberries modded this up to a 5???
Let's make a few things clear:
The attack in question is a method to reset a TCP connection. The TCP reset is launched against one of the two end nodes participating in the TCP connection. The router has NOTHING to do with this. In theory, if an intermediate system like a router goes down, IP will simply find a new path arround the outtage.
The reason that routers feature prominently in this discussion is that Border Gateway Protocol uses very long lives TCP connections. In turn, this means that routers are very vulnerable to this attack. However, the vulnerability effects routers in their roles as an end nodes (sending or recieving data) rather than their role as an intermediate system (forwarding traffic)
And now you blew it! Thanks a lot.
Now if you'll all step this way please...
Hey! He has an Italian typing accent, you insensitive clod!
Slashdot still doesnâ(TM)t support Unicode after it was added to the HTML standard in 1997.
This attack vector has been known for years, and the TCP windowing nonsense has too. Programs like tcpkill have used the RST trick in conjunction with TCP INS windows for a while and have seen quite a bit of use. What's new with this attack that wasn't already in the wild?
What a troll. Yes, because everyone who doesn't setup MD5 is obviously lazy or stupid, unlike you and your smart friends. Please. There is obviously overhead with doing MD5 and it is reasonable not to use it for performance reasons. Anyway, as someone already mentioned, the vulnerability is in TCP which means the MD5 solution works for BGP, which is the most vulnerable, but does nothing for anything else built on TCP (e.g. DNS).
I'm wondering why all the hooplah about this, especially after steps were taken to deal with it before publicizing it... unless at the same time, systems were put in place to ID attempts to exploit the vulnerability.
That would make a lot more sense. Protect against the exploit, publicize it, then watch what happens to determine which groups are most adept at quickly exploiting published vulnerabilities and raid their location. Neat idea for a large-scale honeypot.
Although, most of us know that the majority of exploits are now being deployed by spammers. They don't have any incentive to take major backbones down so this effort might just reveal a few more script kiddies that aren't really the problem.
No, everyone is not vulnerable to the recently published vulnerability in the TCP protocol that allows to shut down BGP routers. Because Cisco hardware is, stupid writers yell that the whole internet is vulnerable. Come on, Cisco is not the internet.
:
:
:)
As stated by Theo de Raadt and Henning Brauer, OpenBSD is not vulnerable because (quoting Henning)
Even without TCP MD5, bgpd on OpenBSD is not affected, because:
we use random emphereal ports
we do not use insanely hughe window sizes as Cisco does
we require the RST sequence number to be right on the edge of the window
(quoting Theo)
That is right. If you have a Cisco, you can tear down BGP sessions by spoofing:
64K of
SYN?s or RST?s sent to #.#.#.#:179 -> #.#.#.#:{1024,+512,+512,...}
The SYN and RST methods are different, but the end effect is that a tiny little burst of packets will cause a flap.
OpenBSD (and I am sure other systems too) have for some time contained partial countermeasures against these things.
OpenBSD has one other thing. The target port numbers have been random for quite some time. Instead of the Unix/Windows way of 1024,1025,1026,... adding 1 to the port number each time a new local socket is established? we have been doing random for quite some time. That means a random selection between 1024 and 49151. This makes both these attacks 48,000 times harder; unless you already know the remote port number in question, you must now send 48,000 more packets to effect a change.
We?ve made a few post-3.5 changes of our own, since we are uncomfortable with the ACK-storm potention of the solutions being proposed by the UK and Cisco people; in-the window SYN or RST?s cause ACK replies which are rate limited.
It will have the most impact on vendors who do BGP over poor TCP stacks. In particular, Cisco.
Cisco has not been teaching engineers to block SYN?s coming in; they have only been teaching them to block SYN-ACK?s from going out in return. And? well, you?ll see.
Ehm, actually OpenBSD is vulnerable. To quote Mike Frantzen : The exploit has a one in 206,703,891,006,465 chance of succeeding. An exhaustive search would require 11,162,010,114,349,110 bytes of traffic which would take 962 days at a saturated gigabit per second. Or two hundred years on a T1.
{{.sig}}
I have no idea about BGP, or the decisions made, but I can speak from the credit card standpoint. It used to be that credit card transactions (not a-sync, TCP only.), would connect, send transaction, wait 10-30 seconds, then disconnect. This has changed over the past 5 years or so for many vendors, who have now switched to an "always up" state. The reason before was bandwidth was an expensive commodity, but with the prices now, it's better to have a connection stay always online so that as soon as there is a connection issue it can be detected by the host server, the thinking there is you can correct many incidents before the customer/store is even aware there is an issue. Security is not a concern for either of the formats as the link must be encrypted, and private.
Mod +5 Drunk
Funny you should mention that scene. I've been to the Smithsonian's storage facilities in Silver Hill, MD on numerous occasions. The final scene of the Ark rolling down an aisle with unknown treasures stacked floor to ceiling on either side isn't too far from the truth. The individual football field-sized containers are called "pods". They're highly guarded and environmentally controlled.
My favorite resident of the pods was the stuffed black rhino that the Smithsonian didn't want to put on display because the animal is extinct and they didn't want any controversy over it.
The scary thing is that if you took the time to look at every individual item on display in the Smithsonian for a few seconds, it would take you several years. If they actually had their entire collection displayed (they have crap tucked everywhere, not just in the Silver Hill storage facility), it would probably take you several lifetimes. There's no telling what they have stashed away.
The Smithsonian's "Secret Repairs" are handled by the Smithsonian Center for Materials Research and Evaluation (http://www.si.edu/scmre/index.asp). SCMRE is, conveniently enough, primarily located at the Silver Hill storage facility.
-- Stu
/. ID under 2,000. I feel old now.
The MD5 auth hack unfortunately fixes only some of the issues here. There is a second way to disrupt streams involving shrinking the MTU to a stupid level, and the "aim for the window" tricks observed in the other attack apply here too.
Going back to 199x it was known that you could hit long lasting streams with ICMP must-fragment mtu = 80 and similar values and basically stall the stream. Some stacks correctly turn off MTU discovery faced with such a claim others ignore it (and break on low mtu links), and others believe it (and break spectacularly). The routters in the middle of the stream have no knowledge of the MD5 or other secrets so can only reply in untrusted form. It is possible to do some checking from the reply data but not full checks.
To make it more fun the proposed fix seems to open a new exploit path that may be worse. Fortunately there is a trivial fix for this case if the problem is confirmed real.
The ultimate problem though is ISPs not filtering packet source addresses. If the governments want to pass one sane bit of 'cybersecurity' law then filtering end users to stop source address spoofing would be it, and require they only used their legitimate assigned addresses (or other addresses properly owned by one way downlinks like satellite etc)
Alan
This isn't a TCP problem, it's just being billed that way because a bunch of vendors have crappy implementations of the above protocals. Yes, in theory this could affect everyone, but the difficulty of doing this type of attack on a system with a good TCP implementation is next to nothing.
Basically, the attack takes advantage of certain predictable behaviors that arn't in the spec but that most of the TCP implementations have to reduce the possible space of packets to something that is reasonably tryable.
The policy of the United States is worse than bad---it is insane. -- Ludwig von Mises, Economic Policy(1959)