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Zimbra Desktop Vulnerable to Man-in-the-Middle Attack 49

Posted by timothy
from the imperfect-world dept.
tiffanydanica writes "For all the flack Mozilla gets about its new security warnings for https sites, at least it warns the user when a mismatch occurs. Sadly the new Yahoo! Zimbra Desktop (released in part to fix some security issues), doesn't bother validating the SSL certificate on the other side before sending along the username and password, making it vulnerable to a man-in-the-middle attack. This is certainly a step up from transmitting the information in the clear, since the attacker must switch from being passive to active, but with all of the DNS security problems, it would be fairly trivial for a malicious attacker to grab a large number of Yahoo! accounts (be it for phishing or spaming). Hopefully this issue will get fixed shortly, but for now Yahoo! Zimbra Desktop users may wish to use the webmail interface."
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Zimbra Desktop Vulnerable to Man-in-the-Middle Attack

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  • by corsec67 (627446) on Sunday November 23, 2008 @02:37AM (#25862923) Homepage Journal

    Since BT is giving Phorm a MitM position [wikipedia.org] in their network, does this mean that Phorm would be able to read the email of anyone that uses Yahoo Zimbra, even if they try to use https?

    • by Sorthum (123064) on Sunday November 23, 2008 @03:02AM (#25862995) Homepage

      The first post is redundant? Odd.

      Anyhoo, no-- Phorm couldn't read it unless they're attempting to MITM SSL by default-- which would get the living crap sued out of them by just about everbody...

      • The first post is redundant? Odd.

        Not even. Pardon me. What I meant to say is that it might seem weird to judge the first post "redundant" until you consider the definition of a nerd to be one who "has nothing better to do" than do whatever we do, right. Assuming that standard of attention to detail is prevalent here, a first post can truly be redundant if it's been said before about the same subject. This is most commonly used for disinformation that's been debunked, especially debunked prominently on /. A re-run of MythBusters can be

  • And also cool.
    • by HTH NE1 (675604)
      SPAME: Single Product Arcade Machine Emulator

      A MAME cabinet set up to play only one game. SPAME cabinets are slowly replacing true original classic arcade games as the original systems fall into disrepair. Of increasing concern of buyers of classic intact games on on-line auction sites.

  • i noticed the flamebait tag? i dont quite get it though, sure its a Hard attack to pull off but given yahoo have ~1/3 of all webmail clients i think people would be up for giving it a try

  • First of all, I don't see any reason why this would be on the Slashdot front page. Many vulnerabilities like this one are discovered every day, and many are more critical and interesting, and concern products that are more widely used than Zimbra. Just take a look at Bugtraq [securityfocus.com] to see a few samples.

    More importantly, we shouldn't promote any random blogger who posts about security vulnerabilities to get t-shirts from Yahoo:

    For anyone from Yahoo! reading this, I'm still waiting for the shirt I was promised from

    • by Anonymous Coward

      You have to give the vendor at least a chance to get the bug fixed.

      No, you don't. For all we know, some black-hat hacker may have already found this vulnerability and be actively exploiting it. Now that he's given a heads-up to everyone, people can use the workaround he suggested - access Yahoo mail through the webmail interface rather than the proprietary binary.

      I accept that it would be nice if he'd informed the vendor first & given them a week to get a patch out, but researchers are not obliged to do that. (E.g. see RFP policy [wiretrip.net], for one example of a well-reasoned

      • by Cow Jones (615566) on Sunday November 23, 2008 @06:41AM (#25863625)

        You have to give the vendor at least a chance to get the bug fixed.

        No, you don't. For all we know, some black-hat hacker may have already found this vulnerability and be actively exploiting it.

        It's the same old discussion every time. There are arguments for and against releasing vulnerabilities without notifying the vendor in advance, I know, but from a developer's standpoint (and from a user's), it's preferrable to give at least a grace period before releasing the details.

        The advantages of releasing immediately are:

        • Users can be told about possible workarounds.
        • There's a better chance of the vendor releasing a patch/fix in a timely manner.
        • You can show off your l33t zero-day skillz.

        The disadvantages are:

        • Any black-hat who hadn't noticed the problem now knows about it and can write an exploit.
        • The entire user base is immediately at risk from script kiddies. If there was no exploit of the bug in the wild, there soon will be.
        • The vendor does not get time to send a security alert and workaround instructions to its registered users or to its security mailing list.
        • The vendor may have to rush the bugfix release before proper testing and QA is complete.

        In this specific case, the Zimbra users are definitely worse off, unless they happen to read Holden Karau's blog (or Slashdot).
        But maybe Holden will get his t-shirt now, so that's ok.

        CJ

        • The disadvantages are:
          * Any black-hat who hadn't noticed the problem now knows about it and can write an exploit.

          I would expect black-hats to have scripts already laying around for such a battleship-sized hole, and not need to be told because their existing network of zombie machines would be so likely to catch that, but I don't know, I am not a black-hat. I do see your point that Friday press releases are bad form though. Unless the vulnerability has been exploited and not identified by the authors, my first reaction is that it probably could have waited until Monday.

          Then again, vulnerabilities that are ignored

          • by Cow Jones (615566)

            I pretty much agree with what you wrote. Just as an addendum, here's a very recent example of a successful cooperation between a person who discovered a security vulnerability (John Resig) and the software vendor (Apple):

            Clickjacking iPhone Attack [ejohn.org]

    • Re: (Score:3, Interesting)

      by Albanach (527650)

      "At the time of the writing Yahoo! security has been notified."

      I do wonder what route he chose to notify them? Maybe an email to postmaster@... ?

      I don't see anything on Zimbra's bugzilla [zimbra.com] which I'd have thought would be the proper place to make such a report.

      Maybe that was too difficult to find, and wouldn't be immediately obvious to other zimbra users. But then there's nothing immediately obvious on the official zimbra forums [zimbra.com] either.

  • I have been wondering if it is possible to catch this with a local http proxy. If you run an http proxy on your own machine, and let all the https traffic go through that, then that proxy would be between your client and any man in the middle. Is it possible to inspect the https traffic and find out early enough, if the certificate is valid, and for the correct domain? (Asking because I don't know https well enough to say for sure myself). I was hoping that could also get rid of the annoying certificate war
    • Re: (Score:3, Informative)

      by gomoX (618462)

      Most proxies just forward HTTPS traffic because they can't do anything else (they can't read the contents of the messages!).

      Technically you could verify the authenticity of the public key proposed by the host (or MitM) because IIRC at that point the communication isn't encrypted yet, but I don't know if there's personal proxying software that can do this.

  • Firefox gets criticised for its new warnings because:

    1. The old mis-match warnings were just fine unless the user doesn't read warnings, in which case the new ones won't help anyway.
    2. They look like errors. They're not errors, they're warnings.
    3. Why can't it just present the page as insecure (no padlock) by default?

    • Re: (Score:2, Insightful)

      by Anonymous Coward

      Firefox gets criticised for its new warnings because:

      1. The old mis-match warnings were just fine unless the user doesn't read warnings, in which case the new ones won't help anyway.

      If you want to work around the certificate error, you more or less have to read the text. Arbitrarily clicking the "go away" button does not do what you would expect. Even once you choose to add an exception, you have to manually press a button to choose to download the certificate, and THEN enable the exception.

      2. They look like errors. They're not errors, they're warnings.

      A bad SSL certificate is an error. These types of rationalization are simply born of outright laziness coupled with gross ineptitude.

      3. Why can't it just present the page as insecure (no padlock) by default?

      It would still say 'https'. Why can't administrators just use non

      • Re: (Score:2, Informative)

        by iammani (1392285)

        2. They look like errors. They're not errors, they're warnings.

        A bad SSL certificate is an error. These types of rationalization are simply born of outright laziness coupled with gross ineptitude.

        Especially since you can even get free ssl certificates from people like http://www.startssl.com/?app=1 [startssl.com]

    • Re: (Score:2, Insightful)

      by Anonymous Coward

      Firefox gets criticised for its new warnings because:

      1. The old mis-match warnings were just fine unless the user doesn't read warnings, in which case the new ones won't help anyway.
      2. They look like errors. They're not errors, they're warnings.

      You can't have it both ways - those two points are contradictory. If they look like an error, then someone who doesn't read them will think they're an error and stop - they'll hit the Home button or whatever. That saved the non-warning-reader from being phished.

      3. Why can't it just present the page as insecure (no padlock) by default?

      Because it's not a big enough clue that you're being attacked by an active man-in-the-middle (e.g. Kaminsky DNS attack). People will miss it - after all, they went to their bank via their bookmark as usual, they're expecting it to be secure. You

  • If a fix gets written it should be named the Tom Shane [shaneco.com] fix because he eliminates the middle man.
  • From software with a name derived from Dadaist nonsense poetry by Hugo Ball?
  • At least Microsoft didn't buy them out in the spring, or we'd be seeing this vulnerability built right into the next Windows kernel!

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