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Null-Prefix SSL Certificate For PayPal Released

An anonymous reader writes "Nine weeks after Moxie Marlinspike presented at Defcon 17, null-prefix certificates that exploit the SSL certificate vulnerability are beginning to appear. Yesterday, someone posted a null-prefix certificate for www.paypal.com on the full-disclosure mailing list. In conjunction with sslsniff, this certificate can be used to intercept communication to PayPal from all clients using the Windows Crypto API, for which a patch is still not available. This includes IE, Chrome, and Safari on Windows. What's worse, because of the OCSP attack that Moxie also presented at Defcon, this certificate cannot be revoked." Update: 10/06 23:19 GMT by KD: Now it seems that PayPal has suspended Marlinspike's account.

11 of 351 comments (clear)

  1. So let me get this right... by Darkness404 · · Score: 5, Insightful

    The people who need to make sure to get everything secure in order to for the web to function have waited longer than -9 weeks- to get something fixed? When the thing was presented at... Defcon? What else do these people have to do other than fix these -major- flaws. When something is shown at Defcon, BlackHat, HOPE or any other major security conference, the first thing for these people to do would be to fix the flaw. 9 weeks is inexcusable.

    --
    Taxation is legalized theft, no more, no less.
    1. Re:So let me get this right... by QuoteMstr · · Score: 5, Insightful

      All of the data binding controls fail to properly HTML encode strings coming from a database. This makes virtually all ASP.NET applications ripe for exploits via XSS or other script injection attacks. The one time I wrote an ASP.NET app, I had to spend weeks going through and replacing all of the simple-looking bind statements with explicit calls to a method that would both bind and encode. Even in the upcoming 4.0 release, the flaw is still there. I suspect that it won't ever get fixed.

      To be fair, that's the kind of thing Microsoft really can't fix: plenty of people depend on outputting HTML stored in the database, and making escaping the default would break these users. We can debate the usefulness of Microsoft's compatibility-über-alles approach, but you can't fix that problem and preserve backward compatibility.

    2. Re:So let me get this right... by nametaken · · Score: 4, Insightful

      For example, the entire ASP.NET API suffers from a similar mismatch of encodings flaw: All of the data binding controls fail to properly HTML encode strings coming from a database. This makes virtually all ASP.NET applications ripe for exploits via XSS or other script injection attacks.

      I would be pretty upset if everything I pulled from DB was automagically HTML encoded. I protect against XSS where it needs to be done. There are places where HTML encoding your data would not work. I do, however, always use parameterized inserts to protect against sql injection on top of an appropriate string cleaning function. Few things aggravate me like shitty ad-hoc inserts and the absence of string cleaning tied to a client-driven interface.

  2. Re:Such dependancies annoy nLite users! by Anonymous Coward · · Score: 5, Insightful

    This has to be the worst advice I've ever heard.

  3. Re:Such dependancies annoy nLite users! by sakdoctor · · Score: 4, Insightful

    NO! Don't roll your own crypto. This is madness!
    *Kicks BikeHelmet into pit*

    OpenSSL is available for windows; use that.

  4. "...PayPal has suspended Marlinspike's account." by magsol · · Score: 5, Insightful

    Because that is totally going to fix the problem.

    --
    "I'd just like to emphasise that taking a million years isn't a metaphor here..." -Rich Bradshaw
  5. Re:Yay Choices! by Excelsior · · Score: 5, Insightful

    I am not a security expert, but does switching to Firefox really solve the issue? For browsing, sure. But everyone is saying this is part of the core crypto API in Windows. Certs are used in more things than just IE.

    When the app you want to install says it is signed by Microsoft, Mozilla, or Nullsoft, can you still be sure that it really is? Can you be sure the Windows Update software is actually retrieving updates without a man-in-the-middle?

    I really don't know the answers to these questions. But I would be surprised if switching to Firefox is a cure to a bug in the core Win32 apis. Helpful: yes. A solution: probably not.

  6. Re:No, but by QuoteMstr · · Score: 4, Insightful

    AFAIK, the law supports your position. But I really think we need to examine whether that's the kind of society we want. It's perfectly fine for a small business to arbitrarily refuse to have a relationship with a particular person. That person can go elsewhere, and the small business is only hurting itself. But large companies like PayPal are different. They form an integral part of the fabric of modern life. When one of these large companies denies service to an individual, that person's quality of life is reduced without an opportunity for rebuttal, or for a fair judgment by his peers. These companies have become de facto utilities, and just as the electric company cannot turn off your lights because of a personal grudge, PayPal should not be able to arbitrarily cripple your ability to send and receive money.

    When a company gains quite a bit from being large enough to matter in this way; it should give something in return.

  7. Re:What about the CA that issued it? by ekhben · · Score: 5, Insightful

    Ahh, you've discovered why SSL on the web is fundamentally broken -- CAs have no incentive to act responsibly, since their customers are certificate requestors, not relying parties. And certificate requestors like CAs who don't have heavy process and high fees.

    I believe the only way forward is for browsers to change the model: associate a certificate SKI with a web site on first visit, warn if that changes. Don't worry about certificate validity, since the hierarchical trust model has been compromised from the root.

  8. ow, retaliate! by Onymous+Coward · · Score: 5, Insightful

    If you cause someone grief, don't expect them to be nice to you in return.

    Look at it this way: If a doctor jabs you with a mortally-needed anti-venom needle, do you have the right to tell him "Fuck off!"?

    I suppose... "He caused me grief!" Yeah, okay. It's a bit of a simplistic metric, really, for determining what is a good response. Appropriate for a young child or a retard. Maybe not for a large corporation. Hopefully not for you.

    It does matter what the person's intentions were.

  9. Re:No, but by lilrobbie · · Score: 5, Insightful

    From Paypal's justification of their banning:
    "We do not, however, allow PayPal to be used in the sale or dissemination of tools which have the sole purpose to attack customers and illegally obtain individual customer information," the spokeswoman, Sara Gorman, wrote in an email. "We consider whether there is any legitimate use in helping to strengthen the defenses of one's site when determining violation of our policy."

    The problem with your statement is that he did not cause Paypal problems in the way that you think. He showed a widespread security flaw, using Paypal as an example... and Paypal suddenly decided that the tools he was producing "have the sole purpose to attack customers and illegally obtain individual customer information". This is a complete and utter load of bollix.

    So yes, Paypal may not be happy they have a vulnerability... the same vulnerability that every other SSL cert user has I might add... but he was not breaking their TOS. What they did was infantile and very counter-productive.

    This kind of behaviour means the only people that know the flaws in your system are the hackers who want to exploit them for nefarious means, rather than these researchers, who are doing it partially to "help the world", but also to HELP YOU.

    I wouldn't trust a company who discourages security penetration testing and thorough investigations of their systems in these ways. Because you can bet your pants, the black-hat hackers will do their homework and find these flaws if our researchers don't.