OpenBSD Will Not Fix PRNG Weakness 196
snake-oil-security writes "Last fall Amit Klein found a serious weakness in the OpenBSD PRNG (pseudo-random number generator), which allows an attacker to predict the next DNS transaction ID. The same flavor of this PRNG is used in other places like the OpenBSD kernel network stack. Several other BSD operating systems copied the OpenBSD code for their own PRNG, so they're vulnerable too; Apple's Darwin-based Mac OS X and Mac OS X Server, and also NetBSD, FreeBSD, and DragonFlyBSD. All the above-mentioned vendors were contacted in November 2007. FreeBSD, NetBSD, and DragonFlyBSD committed a fix to their respective source code trees, Apple refused to provide any schedule for a fix, but OpenBSD decided not to fix it. OpenBSD's coordinator stated, in an email, that OpenBSD is completely uninterested in the problem and that the problem is completely irrelevant in the real world. This was highlighted recently when Amit Klein posted to the BugTraq list."
then exploit it (if you can) (Score:5, Insightful)
nothing says "fix it" faster than a few thousand compromised hosts
release a PoC that gets r00t, inform the security lists and stand back
thats what full disclosure is for.
if it isnt exploitable then BSD can fix it at leisure
or if thats not quick enough and as its Open Source, YOU fix it if you are that concerned
now somebody call the whhaaambulance
Re:then exploit it (if you can) (Score:5, Informative)
Re:then exploit it (if you can) (Score:5, Informative)
Anyway, besides rudely just posting a link like that in response, I was going to say that proof-of-concept code has at least already been published, and his point is that FreeBSD, NetBSD, DragonFlyBSD has fixes available. Apple is currently working on a fix for OS X. OpenBSD is not planning to fix this. More info can be found in my parent link.
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You probably did a typo in a closing tag. Anyway, There's a reason why we have a "preview" button
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Re:then exploit it (if you can) (Score:4, Informative)
Quantum mechanics delivers true randomness, at least according to the standard interpretation.
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I would have thought all algorithmic solutions to random number generation would suffer the same flaw as described in the text. Be in deep shit if it worked any other way.
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Imagine a spin-1/2-particle (e.g. an electron). Such a particle has the peculiar property that if you measure its spin along any chosen axis, you'll always get either 1/2 ("spin up") or -1/2 ("spin down").
OK, let's assume we have just measures the spin in z direction and got +1/2. Let me first note that this is stable: If we measure the z-spin of the same particle again (assuming it didn't interact in between), we will again get +1/2 each time. That is, once we measures +1/2 in z
Re:then exploit it (if you can) (Score:5, Funny)
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Sure, it's called "The Laws of Physics".
The only problem is, nothing can calculate the result faster than our universe is already doing. It's hard to make something that can calculate the behavior of a quark that is smaller than a quark.
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Kinda hard to make some if nothing in our world are truly random.
Almost all processes in a computer are truly random. The number of electron crossing this particular trace per second? It's certainly not constant.
The trick in computers is keeping the RAM and the harddisk from going random too fast, such that a temporary illusion of determinism can be achieved. A crossing cosmic-ray particle will flip every last bit at random -- it'll just take sufficiently many centuries that you can imagine your bits to be stable zeros and ones.
Back in the eighties I generated trul
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Because it is not part of the standard PC architecture ?
Re:then exploit it (if you can) (Score:5, Informative)
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True, but if you roll one yourself, the P in PRNG no longer has a second meaning of 'predictable.'
It does if you don't do it right, and you're unlikely to do it right unless you're a cryptographic expert. Just because your algorithm isn't published doesn't mean a competent codebreaker won't be able to crack it: ahref=http://en.wikipedia.org/wiki/Security_through_obscurityrel=url2html-8229 [slashdot.org]http://en.wikipedia.org/wiki/Security_through_obscurity>.
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Uh what (Score:4, Insightful)
Re: Uh what (Score:5, Informative)
Thus, it is my guess that even if the attack vectors are deemed serious enough, the OpenBSD team has decided that it doesn't matter, since these protocols were never designed for security anyway, and that one should use DNSSEC and/or IPSEC (or TLS) if one actually wants to be secure (it does raise the question as to why they decided to use a PRNG for those fields from the beginning, though). My second guess is that they don't even consider the attack vectors serious, though, since they probably require a cracked router to be effective anyway.
Indeed, if they do require a cracked router, then I don't see the issue to begin with. One of the attacks was that the attacker could inject data into a TCP stream and such things, and if he has a router cracked, then I'm pretty sure he could forge all the data he wants anyway, without using any particular software attack at all, and likewise with DNS data.
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Re: Uh what (Score:5, Informative)
The exploit described in the paper doesn't require a cracked router, just a malicious website. Once you can inject fake DNS entries for bankofamerica.com or ebay.com on some ISP's DNS server, the exploit has paid for itself.
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They'd more likely be used to compromise the user (Score:3, Insightful)
Not everything is about compromising someone's computer.
Re:Uh what (Score:5, Interesting)
It is entirely believable to me. Back in 1995 I told Marc Andressen at Netscape that he had a serious problem with the random number generator used to choose session keys for SSL. There was simply not enough randomness going in for there to be 128 bits going out.
Marc had every reason to listen to me, I had broken SSL 1.0 in ten minutes when he tried to demonstrate it at MIT. But it took several weeks to drill the problem into his thick skull.
So they eventually asked me for a description of how to do the thing right.
A year later the exact same bug was discovered independently. By this time they had hired some competent crypto people. I spoke to Taher about the problem later and his explanation was that they found the design note on the PRNG which was so comprehensive that they didn't think it necessary to check the actual code.
Re:Uh what (Score:5, Funny)
Re:Uh what (Score:5, Funny)
That's because he's so l33t he can pick a Slashdot id at random every time he posts.
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On SSL/TLS and similar security/crypto issues, he is always interesting and more likely to be right than not.
On supporting large scientific computing platforms, he is always interesting and more likely to be right than not. His system administration c.v. is impressive.
On interpreting the experiments performed
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Marc's 128 bit encryption used a random seed with 24 bits worth of ergodicity. So it was only 24 bit secure.
And SSL 1.0 had no integrity protections whatsoever, which would have been pretty bad even if he wasn't using a stream cipher. So even if he used a 256 bit cipher it would have been broken.
What makes you think this is my only Slashdot id?
Oh and in response to the AC in the other thread, no my job title is not
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I have noticed that people are complete and utter idiots about two very important cryptographic algorithms. PRNGs and hash functions. I can't believe the number of people who still use a simple MD5 hash for software download verification. First, it isn't signed, so all someone has to do is alter both the hash and the code. Secondly, even if it were it's not very hard to make two pieces of code, one innocuous and one malicious that both have the same MD5 hash, and it's been true for years.
DNS cache pois
MD5 (Score:2)
I'm calling you on this claim.
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If BSD used the GPL, then Apple still wouldn't be providing a fix, because they wouldn't be using OSS at all. Neither licence is better than the other in this regard.
I don't agree with the trolling from either camp. The licence you release your code under is a matter of personal choice.
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While I would agree with you on the matter of trolling it really gets old when BSD users trumpet it constantly where-as in my experience GPL supporters tend to realise there are limitations. Of course I'm sure it is seen the same way across the bridge.
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Out of the four items you mention, only one is GPL. You could have done much better to suggest such examples as GCC et al.
The great thing about the BSD license, is that when people do contribute back (and they do, even big companies like Apple), you know its because they *want* t
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Software freedom is better when its inalienable. (Score:4, Interesting)
So, in other words, the grandparent poster's point is valid and the larger more important issue remains: proprietary derivatives of non-copylefted free software uses the free software community as a market instead of treating us as equals.
Nobody "has" to under the GPL; to the degree that what you said is true, the same is true of the GPL. Statements like yours ignore all the choices that lead up to distributing source code. There's nothing in the GPL that compels conveyance. There are only conditions in the GPL that compel source code conveyance with object code conveyance. It's trivially easy to not improve GPL-covered software or not distribute the improved version. The larger issue here is whether the free software community owes Apple anything. We don't. If they want to join us and work with us, great, if not they can write their own software. The GPL helps ensure that when people and organizations convey copies of programs they do so as equals. NeXT (now owned by Apple) already tried distributing GCC derivative software without distributing complete corresponding source code when GCC was under GPLv2. It made NeXT look like an ass and put them at risk of being able to distribute GCC at all. NeXT later rectified the situation by distributing complete corresponding source code in compliance with GPLv2.
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Oh, and captain hater, last time I checked, the fix would be shared [apple.com].
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Because that is why they aren't using webkit, apache, samba, cups (or employ the guy who writes it), and several others in their default install.
....none of which touch proprietary hardware or deal with DRM.
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http://www.opensource.org/licenses/bsd-license.php [opensource.org]
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Apple are free to release their putative fix to the community, or not - their free choice. That's one more freedom, relative to being obliged to release any changes they make which lead to a binary release outisde of Apple, which the GPL would oblige.
There are plenty of folk who see that as a feature not a flaw.
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(So possibly it's the GPLv3 is compatible with the Affero license...but the resulting code must be released Affero.)
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Re:Uh what ... yeah (Score:4, Insightful)
Don't conflate "things you want" with "freedom", please.
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I personally don't care
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GPL has the same flaw, ya know. (Score:3, Insightful)
( * which only says something about making the code, and thus the fix, available if the code, or compiled version thereof, is distributed. )
The difference is trivial, isn't it. In both cases an existing fix would not automatically be contributed back.
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Freedom doesn't me
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And yes, Affero GPLv3 would indeed make this apply to Google if they were using it as a server-side solution. But if it's in-house only - they still don't have to contribute back. If they (or anyone) develop for a specific client only, then only that client
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The phrase "security through obscurity" has a well established meaning in the discussion of security measures. It refers specifically to systems that are only secure if the design is not known to the attacker.
Specific passwords (or other shared secrets like symmetric keys) are not part of the design. The design merely says that you use one, not which one you use - and security of the shared secret is only based on keeping which key / password
Why this is so bad: DNS cache poisoning (Score:2, Informative)
OpenBSD secure?! (Score:4, Interesting)
Oh for Bob's sake! (Score:2, Insightful)
But when the PRNG for a non-MS operating system is shown to have a similar (but not identical) problem, it's "irrelevant"?
Troll? Redundant? (Score:2)
Perception is as important as actuality (Score:2, Insightful)
Can someone say how hard a fix would be ? Surely: for the sake of a bit of work they are committing a public relations blunder!
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The next thing is that anything *nix or open source is not really interested in security.
Remember that it is easier to loose reputation than to gain it.
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Nobody forces you to use OpenBSD, and nobody prevents you from patching it yourself. They are entirely in their rights to say "No" even if it is a stupid thing to do.
XYZ Attacks were also unthinkable a while ago. (Score:2, Informative)
But I wanted to show that most of todays security threats
were first percived hard to be used or totally unthinkable, even minor security problems
which later were updated to the status of a serious threat, because the first look turned out to be wrong.
So when devellopers commit themselves to build the most secure OS, and than on the other hand show such no-interest
Strike 2, OpenBSD. (Score:5, Insightful)
First they refused to implement WPA (despite the other BSDs having it), because it "doesn't provide real security" and "just use IPSEC".
Now they're refusing to address a weakness in their network stack (despite the other BSDs addressing it), again with the implication that everybody should just jump to IPSEC. What if you're in a situation where an IPSEC rollout is impractical or impossible?
Whatever happened to defense in depth? Whatever happened to "secure by default"? Whatever happened to constructive paranoia, such as randomizing of libc addresses, that was unlikely to have any real impact on security but was a nice extra, just in case? Why must I now upgrade to NetBSD to get security features that are lacking in OpenBSD? Isn't the shoe on the wrong foot?
What happened? Was there a change of management? Is OpenBSD under the thumb of a douchebag patch manager lately? Is this going to go away at some point? Those of us that sleep with OpenBSD firewalls like a gun under our pillow are taking notice.
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Umm, they're completely correct to take this stance. WPA is far inferior to IPSEC, security-wise. It's OpenBSD's job to help insulate you from insecure technologies. We could easily say, "Just because FreeBSD allows one-character passwords, OpenBSD should, too!" And you know what? We'd be wrong to think in that way.
What happened? Was there a change of management? Is OpenBSD
Re:Strike 2, OpenBSD. (Score:5, Insightful)
So, OpenBSD is refusing to put a locking mechanism on the doorknob because it wants to make people use a deadbolt. Me, I'd want both; if it turns out my deadbolt had a defect and thus easily defeated, the doorknob lock would at least provide some security.
Theo is slow to change, but he will. (Score:5, Interesting)
Basically, he's very conservative, very resistant to change, and don't forget that's one of the things that made OpenBSD what it was to begin with... but if it really matters he'll come around.
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From my impression that is an overstatement. OpenBSD will get WPA when someone writes it well enough for it to get in. Although the current devs don't want to write it themselves (as they don't feel they need it), they have left the door open for someone else to write it.
"doesn't provide real security" and "just use IPSEC" aren't reasons why it won't get in at all but reasons why that particular developer(s) isn't going to bother writing it themselves. OpenBSD is probably
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They're doctrinaire, sure (Score:3, Interesting)
OpenBSD wont fix? (Score:2)
What you really mean is 'Theo doesn't use this feature, so it cant possibly be important to anyone else in the world'. OBSD is a one man show.
How many people actually use PRNG? (Score:2)
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It's my understanding that urandom often uses data from interrupts, keyboard input, device controllers etc. to increase the entropy of the random numbers it produces.
Hardware random number generators are not considered pseudo-random. As I understand it they usually ampli
Code excerpt for the curious... (Score:5, Funny)
random vs pseudo-random? (Score:2)
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The rest of it either isn't necessarily random, or isn't necessarily cheap enough / fast enough. And PRNGs can be made hard enough to guess that no one will. It's kind of like how RSA is possible to crack, if someone guesses the right prime factors, but with a sufficiently large key size, you can get to where all of the matter in the Universe, assembled into chips that vaguely resemble today's p
From the forum post: (Score:2)
But it gets more interesting. Several other BSD operating systems
copied the OpenBSD code for their own IP ID PRNG, so they're
vulnerable too. This is particularly so with Apple's Mac OS X,
Mac OS X Server and Darwin, but also with NetBSD, FreeBSD and
DragonFlyBSD (the 3 latter O/S however only use this PRNG when
the kernel flag net.inet.ip.random_id is set to 1; it is 0 by
default, resulting in a sequential counter to be used instead...).
This is really a ways out of my depth, but my naive understanding is that the PRNG is a problem because it is not actually random, and can therefore be predicted. Yet, the above states that the other BSDs in particular don't even use the randomization by default, and instead use the most predictable sequence possible. Am I missing something, or doesn't that mean the other BSDs are significantly more at risk (for whatever value of 'at risk' this threat actually corresponds to)?
-Ted
Why doesn't software trust /dev/[u]random ? (Score:3, Informative)
I had an interesting discussion with Amit regarding all the hacks people (including the Bind people) do to try to roll their own random number generator and it prompted me to review our own IP randomization code (and the 'off' default). After review I was decidedly uneasy about its secureness, mainly because it was trying to use an algorithmically generated cycle for a tiny namespace (16 bits, actually 15 the way it was coded). The problem with the IP sequence space is that you can't just randomize it, you also have to ensure that sequence numbers are not immediately repeated. DNS has similar issues.
I gave up trying to improve the algorithm and decided to throw in the towel and allocate 128KB of memory to do a look-ahead running shuffle of the 65536 possible sequence number using the system's PRNG. It's not possible to do better then that, frankly. We also decided to turn on ip randomization by default.
So that brings me back to the question: Why the hell doesn't bind have an option to use the system PRNG? Not all systems have a good random number generator, but I trust ours far more then the junk coded into bind. For that matter, I don't really mind if bind ate another 128K of memory to secure its own sequence space, if that is what it takes.
I know enough about cryptology to know that I am not a cryptographer. But regardless of that, I can still get a good feel for someone else's code and what BIND does scares me. The y need to change their code to default to something more secure, even if it is memory intensive. If they want to give their users the option to use the less memory intensive algorithm that's fine with me, but the default needs to be more secure.
DNS has its own design issues, but that is no excuse for software to exasperate them.
-Matt
Re:So much for high security (Score:5, Insightful)
The OpenBSD guys are pretty defensive about security. If they say it is not a problem, I am inclined to believe them.
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OpenBSD's argument is that a patch would not make it more secure... so your point is moot.
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Re:If the OpenBSD devs say it isn't a security fla (Score:2, Insightful)
I see you don't remember how OpenBSD developers downplayed remote root vulnerability in mbuf code, until COREsecurity gived them working exploit
And this is that mega randomness with what OpenBSD team was so proud
Re:What?? (Score:5, Informative)
This could potentially provide a platform for attacks involving prediction of IP sequences and thus TCP data injection attacks.
Where is a local machine access required for that? It could provide attacks on the network traffic itself, by merely knowing which operating systems are involved in it.
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Your dollar, your time (Score:2, Insightful)
As we can see, even Microsoft can't seem to be vigilant on everything at once.
And the question to ask would be, what alternative? OpenBSD has (yet another) theoretical vulnerability. Is it one that affects the things you use obsd for?
MSWxxx has yet another real vulnerability. Is it one that affects what you use MSWxxx for?
It's better to allocate your time to be vigilant on things that matter (to you).
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If flawed, predictable PRNG code is so 'irrelevant in the real world' why does even Microsoft seek to improve upon it?
"Strengthens the cryptography platform with a redesigned random number generator, which leverages the Trusted Platform Module (TPM), when present, for entropy and complies with the latest standards. The redesigned RNG uses the AES-based pseudo-random number generator (PRNG) from NIST Special Publication 800-90 by default. The Dual Elliptical Curve (Dual EC) PRNG from SP 800-90 is also availa
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Because they have like six Turing award winners working for them including Butler Lampson? Of the top fifty people in network security you will find about a quarter work for Microsoft, more than for any other company, including IBM, RSA and VeriSign. They have the cash and they use it to buy the best.
Microsoft's problem is that you can't buy your way out of a shitty legacy code base in
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which leverages the Trusted Platform Module (TPM)
I smell marketing droid oil. I do favor fixing security issues, but as soon as the TPM becomes involved, rational assumptions vanish. MS has a history of *fixing* things to include new technologies they are having a hard time pushing. TPM is a huge technology for them that they have had an incredibly difficult time pushing. Microsoft needs this technology to win for their game plan to succeed. Trusted Computing in general and remote control of custome
Using hardware to assist a PNRG =!= lock-in (Score:2)
Your assertion that using hardware to reduce the determinism and thus reduce the predictability of a PNRG must be some sort of strategy to lock hardware and software together betrays an ignorance of the problems that comp
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Still Alive, BSD version, sung to the tune of Jonathan Coulton's "Still Alive" from the game "Portal," originally vocalised by Ellen McLain in character as GLaDOS. I be asserting me fair use right of parody, yarr!
This was a triumph,
I'm logging a note here: Huge success,
We had to dummynet the heavy traffic,
BSD Unix (R),
We code what we must because we can,
For the good of all of us,
Including vendors as well,
But there's no sense crying over closed source