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Why One-time Passwords Suck For MITM Attacks

Posted by CmdrTaco on from the my-password-is-pass1234 dept.

whitehartstag writes "Black Hat 08 disclosed several SSL VPN and DNS vulnerabilities that caused several people to sit up and take notice. Some of these new exploits performed a brilliant Man-In-The-Middle attack on SSL VPN tunnels. This article walks you through how using certificates, instead of OTP tokens, for second-factor authentication can increase the security of your SSL VPN against these new types of attacks."

19 of 138 comments (clear)

  1. The Love Triangle... by kcbanner · · Score: 5, Funny

    Alice and Bob's relationship will be at stake when an unknown interloper...Larry...arrives on the scene. Is this love line segment about to become a love triangle? Will the self-signed certs be accepted?

    Coming to you this fall...Larry is...The Man in the Middle.

    --
    Obligatory blog plug: http://www.caseybanner.ca/
  2. xkcd comic by khasim · · Score: 3, Funny

    http://xkcd.com/177/

    Eve

    1. Re:xkcd comic by Anonymous Coward · · Score: 4, Insightful

      You do know that you don't have to click on every link that you see on a web page, right?

    2. Re:xkcd comic by eln · · Score: 4, Funny

      http://xkcd.com/406/

    3. Re:xkcd comic by Chyeld · · Score: 5, Funny

      Is anyone else on the Internet SICK TO FUCKING DEATH of every story/article/anything having a XKCD comic posted as a link in it?

      No.
       
      Summer Glau

    4. Re:xkcd comic by Anonymous Coward · · Score: 5, Funny

      Well just in case he doesn't know...

      Knowing is half the battle.

    5. Re:xkcd comic by smallfries · · Score: 3, Funny

      Is anyone else on the Internet SICK TO FUCKING DEATH of every story/article/anything having a XKCD comic posted as a link in it?

      My hobby:

      I like to post an xkcd link into every story I come across...

      --
      Slashdot: where don knuth is an idiot because he cant grasp the awesome power of php
    6. Re:xkcd comic by Culture20 · · Score: 3, Funny

      That is no-where near an exhaustively-researched word-by-word rebuttal.

      OK...

      Is

      Isn't

      anyone

      everyone

      else

      this

      on

      off

      the

      Um... you win.

  3. frequency in the wild ? by jacquesm · · Score: 4, Interesting

    I know that there are some people that are very clever at doing these man in the middle attacks, but they usually happen in an academic setting as proof of concept.

    Have there been documented cases of (successful) mitm attacks on banks or other high profile targets ?

    --
    MP3 Search Engine
  4. This is NOT an attack on SSL VPN by ugen · · Score: 5, Interesting

    This isn't an attack on anything, really.

    Here is what the article says:
    "They will then go to all of the trusted CAâ(TM)s and try to get them to issue them a valid âoeinternal onlyâ certificate with the FQDN of a target sslvpn URL. As soon as they get a success, that company now becomes their target of choice. Remember, the certificate they need can be issued from any trusted CA in the browser and does not need to match the CA that the SSLVPN gateway is using."

    Now, may be I am not understanding the purpose of SSL certificates and the PKI infrastructure in general, but I was under distinct impression that the whole reason those authorities exist is to verify who they give the certificate to, and in such a way that we, users, can trust these certificates.

    If this is not correct, and anyone can with relatively minor effort get certificate for a random domain name from one of recognized cert. authorities - game over, none of this matters, the entire PKI infrastructure is in the crapper.

    So, either we have to deal with cert. authorities signing things they should not or this is not an attack that is worth discussing. Everything else is a half-measure.

    1. Re:This is NOT an attack on SSL VPN by Diss+Champ · · Score: 5, Funny

      Cert authorities are notorious for poor checking. The main thing they check is that they are getting paid. There are things certificates are good for- knowing for sure the first time you see one for a site that they are who they claim they are without further checking is not one of them.

    2. Re:This is NOT an attack on SSL VPN by Sloppy · · Score: 4, Insightful

      Authority is subjective. Once everyone realizes this, they might as well switch to the OpenPGP trust model, which acknowledges it, instead of trying to hide this inescapable truth from the user.

      --
      As copyright owner of this comment, I authorize everyone to defeat any technological measure which limits access to it.
    3. Re:This is NOT an attack on SSL VPN by tgd · · Score: 4, Informative

      You miss the point -- they are issuing a valid cert for an internal address.

      "intranet" would be an example. Not intranet.mydomain.com.

      Since your DNS will append mydomain.com automatically, it leaves you vulnerable to anyone who installs an "intranet" cert on a server they have spoofed into your DNS if you the browse to "intranet".

      If "intranet" is an SSL VPN, then they can get in the middle and get your OTP.

  5. long story short... by brunascle · · Score: 5, Interesting

    The guy was able to buy a certificate for Microsoft's login.live.com, from an undisclosed CA that's trusted by IE by default, because he checked a box saying it was only going to be used for internal use.

    Please reveal the CA. They need to be shut down.

    1. Re:long story short... by jacquesm · · Score: 5, Insightful

      Shutting them down is stopping short, all the certificates issued by them need to be revoked as well and reissued by another CA after thorough checking.

      If there is one documented case there are likely to be many more undocumented cases.

      --
      MP3 Search Engine
    2. Re:long story short... by QuoteMstr · · Score: 5, Insightful

      Somebody, preferably a government agency, should be in charge of testing CAs. CAs have very strong economic incentives to loosen verification rules in order to compete and sell more certificates. When one CA loosens its rules a little bit, all the others are compelled to do the same to stay competitive. It's a race to the bottom.

      Market forces cannot solve the problem because there's a fundamental information asymmetry. Joe Myspace isn't going to understand what a root CA is, much less manually remove it from his browser. And even if he did understand what that meant, would he lose access to his favorite SSL-protected sites for some egghead's paranoid security fears?

      We need regulation, and we need it now. We need several free, worldwide certificate revocation lists, and we need agencies running these lists to randomly and anonymous ensure CAs are following the verification rules.

      Having just one CRL gives too much power to one authority, which is especially dangerous if these authorities are organs of government. Browsers should check all CRLs and consider a certificate invalid if, say, two-thirds of the CRLs say to do so.

      In any case, the current situation is untenable.

  6. Thawte by an.echte.trilingue · · Score: 4, Informative

    Thawte does this; look about halfway down the page

    I must say that in general I have been unsatisfied with thawte. They gave me a hard time about re-issuing my cert after the debian-ssl debacle and in general their tech support people don't know anything beyond what is already on their site.

    Seriously, I pay over a hundred clams a year just to so that I can have ssl communication without the "OMFG THIS SITE IS GONNA HAXOR YOU" dialog box pop up in user's browsers, and they pull all kinds of monkey business.

    But since verisign owns them, I wouldn't hold my breath for them to be shut down. My guess is the other CAs do this, too.

    --
    weirdest thing I ever saw: scientology advertising on slashdot.
  7. Roll yer own... IPCop and Zerina OpenVPN by Anonymous Coward · · Score: 3, Interesting

    I made a VPN server using IPCop and added the Zerina OpenVPN package to it. Simple plug and play. It has it's own internal certificate authority, and issues it's own client certificates for each road warrior client you set up to be an OpenVPN client under the Zerina webgui. Very secure, since it will only accept the client certificates that were generated locally to the machine. The cost for the software, is of course FREE. The old AMD Athlon 2400 Compaq PC upon which I'm running it, is worth maybe $200 tops, including the second NIC card I had to put into it to make it a true dual-homed Linux firewall. It supports 15-20 concurrent roadwarrior connections easily, then my single T-1 line is saturated long before the IPCop box reaches any significant load.

  8. I don't see how this is much better? by JSBiff · · Score: 3, Interesting

    I might be missing something here, but this article proposes, as a way of trying to make the management of keys/certs easier (which is necessary to implement the client-side certs), to use this "SecureAuth" system. . . which downloads an SSL cert to your computer. So. . . uhh, why can't an attacker intercept this? Well, the answer seems to be (maybe I'm misunderstanding here) that before the SecureAuth system will download the cert to you, it sends you some sort of one-time-password via phone or SMS, which you must enter to get the key . . . but once you've typed in this one time password you got by phone, what prevents the MITM from intercepting that passsword the exact same way it would have been attacking the other one-time-password generated by the keychain fob, and therefor be able to impersonate you to the SecureAuth server and get the client cert which should have been sent to you?