Zimbra Desktop Vulnerable to Man-in-the-Middle Attack 49
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."
Phorm reads your Email? (Score:5, Interesting)
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?
Re:Phorm reads your Email? (Score:4, Informative)
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...
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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
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Spaming is fun. (Score:2)
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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.
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There's always DNS cache poisoning...
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Or captive networks. There is a guy at your college/company that controls your DNS, unless you explicitly set an external DNS.
This doesn't mean that anyone can trivially get into your mail, but it does man that more people than should can, and furthermore that this is trivial to prevent.
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I am pretty sure my workplace is trying to pull this off but it includes providing their own versions of certificate providers certs by controlling the client binaries.
It'd be easier to present a self-signed certificate for every HTTPS connection and simply install your own root certificate on every client PC. Easy enough when you control the client PCs.
Any SSL-protected connection assumes that you either control or have complete trust in the client PC you're sitting at and the system(s) at the other end. If either of these are not true, then you must assume that the security is compromised.
(Of course, in these days of spyware and keyloggers, you can't necessarily be ce
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So a man in the middle would decompile the program, change the address it goes to, then recompile it, and that's going to be stopped if it used HTTPS?
I do realise man-in-the-middle attacks are possible. But what you described certainly isn't one.
Re:man in the middle (Score:5, Informative)
As aussie_a said, what you describe is in no way similar to a man-in-the-middle attack. 'MITM' refers to be the ability to eavesdrop on and forge network traffic. Fake login pages is part of 'phishing'.
http://en.wikipedia.org/wiki/Man-in-the-middle_attack [wikipedia.org]
http://en.wikipedia.org/wiki/Phishing [wikipedia.org]
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Phishing does not exclude MITM attacks.
If the phishing site acts as a proxy to the real site - as described by the GP - it IS a MITM attack.
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Merlin comments on the validity of your description, but regardless how would HTTPS change that?
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If all you need is an encrypted end-to-end connection over SSL (say for a management front-end), the self-signed is fi
Re:man in the middle (Score:5, Informative)
How do you just jump in the middle of someone's connection?
There are a number of ways to do it. You can:
There are probably a few other ways to do it, but that's all off the top of my head.
flamebait? (Score:2)
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
Responsible disclosure? (Score:2, Insightful)
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:
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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
Re:Responsible disclosure? (Score:5, Informative)
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:
The disadvantages are:
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
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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
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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]
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"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.
Local http proxy? (Score:2)
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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 error messages (Score:1)
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?
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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
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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]
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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
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man in the middle vulnerable attack you!
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While 'Man in the Middle' attacks are certainly theoretically possible, but, has there ever actually ever been a verified MitM attack? Links appreciated if they exist.
That's an extremely good question. My instinctive guess is "probably not involving a mainstream use of the Internet, eg. online banking or shopping" - mainly because MitM attacks require quite a bit of effort and would be quite difficult to set up without leaving a dirty great trail. Far easier to get keylogging spyware and grep for "www.majorbank.com" or run a phishing scam.
Once you get into things like online espionage (being carried out by governments with lots of money and the will to ensure that the
Name the fix (Score:2)
What do you expect? (Score:2)
At Least... (Score:1)