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Microsoft Tries To Censor Bing Vulnerability

An anonymous reader writes "Microsoft's Bing search engine has a vulnerability with its cash-back promotion, which impacts both merchants and customers. In traditional Microsoft fashion, the company has responded to the author of the breaking Bing cash-back exploit with a cease & desist letter, rather than by fixing the underlying security problem. It is possible for a malicious user to create fake Bing cash-back requests, resulting in not only fake cash-back costs for the merchant, but also blocking legitimate customers from receiving their cash-back from Bing. The original post is currently available in Bing's cache, although perhaps not for long. But no worries, the author makes it clear that the exploit should be painfully obvious to anyone who reads the Bing cash-back SDK."

26 of 275 comments (clear)

  1. And now thanks to /. and microsoft by Shadow+of+Eternity · · Score: 5, Insightful

    it will probably be all over the rest of the internet and general common knowledge within the week.

    --
    A bullet may have your name on it but splash damage is addressed "To whom it may concern."
    1. Re:And now thanks to /. and microsoft by u38cg · · Score: 5, Funny
      That seems pretty unlikely to me.

      ~Barbara

      --
      [FUCK BETA]
    2. Re:And now thanks to /. and microsoft by Shadow+of+Eternity · · Score: 4, Insightful

      GP just wants someone to hate on, you don't get much more neutral in phrasing than that without making a two word post saying only "Streisand effect."

      --
      A bullet may have your name on it but splash damage is addressed "To whom it may concern."
    3. Re:And now thanks to /. and microsoft by Anonymous Coward · · Score: 5, Informative

      like this you mean?

      Breaking Bing Cashback
      Posted November 4th, 2009 by Samir

      I've never bought anything using Bing Cashback, but the balance of my account is $2080.06. Apparently, I placed two $1 orders on January 24th of this year, and spent another $104,000 on October 24th. Let's see how these transactions might have "accidentally" got credited to my account.

      First, we need to try to figure out how transactions get into Bing Cashback. Microsoft posted some documentation here. The explanation of how a merchant reports transactions to Bing starts on page 20. Merchants have a few options for reporting, but Bing suggests using a tracking pixel. Basically, the merchant adds a tracking pixel to their order confirmation page, which will report the the transaction details back to Bing. The request for the tracking pixel looks something like this:

      https://ssl.search.live.com/cashback/pixel/index?
      jftid=0&jfoid=&jfmid=
      &m[0]=&p[0]=&q[0]=

      This implementation, while easy for the merchant, has an obvious flaw. Anyone can simulate the tracking pixel requests, and post fake transactions to Bing. I'm not going to explain exactly how to generate the fake requests so that they actually post, but it's not complicated. Bing doesn't seem to be able to detect these fake transactions, at least not right away. The six cents I earned in January have "cleared," and I'm guessing the remaining $2080 will clear on schedule, unless there is some manual intervention.

      Even if Bing detects these fake transactions at some point in the future, the current implementation might have another interesting side effect. I haven't done enough work to say it with confidence, but a malicious user might be able to block another user's legitimate purchases from being reported correctly by Bing (I only tried this once, but it seemed to work). Posting a transaction to Bing requires sending them an order ID in the request. Bing performs a reasonable sanity check on the order ID, and will not post a transaction that repeats a previously reported order ID. When a store uses predictable order ID's (e.g. sequential), a malicious user can "use up" all the future order ID's, and cause legitimate transactions to be ignored. Reporting would be effectively down for days, causing a customer service nightmare for both Bing and the merchant.

      Based on what I've found, I wouldn't implement Bing Cashback if I were a merchant. And, as an end user and bargain hunter, it does not seem smart to rely on Bing Cashback for savings. In our next blog post, I'll demonstrate some other subtle but important reasons to avoid using Bing Cashback.

    4. Re:And now thanks to /. and microsoft by theurge14 · · Score: 4, Insightful

      Wow, I didn't realize that there are people that still believe in that 'security through obscurity' nonsense.

    5. Re:And now thanks to /. and microsoft by mcvos · · Score: 5, Insightful

      Financial transactions based on a tracking pixel? Really? I just don't know where to start to point out how wrong that is.

      PayPal has dozens of different ways to pay, and most of them suck, but at least they don't encourage people to rely on tracking pixels. Either you explicitly send the customer to the payment gateway (including login or entering credit card info there) to authorize the transaction, or you have your own server talk directly to the payment gateway. Relying on a hidden browser-side hack for a financial transaction is just amazingly stupid and unnecessary, even if you don't spot any obvious flaws right away (because someone else will).

    6. Re:And now thanks to /. and microsoft by buchner.johannes · · Score: 5, Insightful

      In traditional Microsoft fashion, the company has responded to the author of the breaking bing cashback expoit with a cease & desist letter, rather than by fixing the underlying security problem.

      Maybe they are doing both?

      The cease and desist letter seems partially reasonable:

      Specifically, at this site you are providing information directing users how to misuse the microsoft Bing Cashback program through unauthorized technical means. Further, on this website you admit that you have personally misused the Cashback program in this regard.

      It's pretty stupid to admit you violate a law on a blog that has your name on it. He should have used a anonymous blog for that or inform Microsoft of the issue in the first place.

      --
      NB: The message above might reflect my opinion right now, but not necessarily tomorrow or next year.
    7. Re:And now thanks to /. and microsoft by QuoteMstr · · Score: 4, Interesting

      Relying on a hidden browser-side hack for a financial transaction is just amazingly stupid and unnecessary, even if you don't spot any obvious flaws right away (because someone else will).

      And people often do precisely that for affiliate programs. Is it any wonder these programs make up one of the shadier areas of the internet?

    8. Re:And now thanks to /. and microsoft by Homburg · · Score: 5, Insightful

      I'm not sure how this is a sensible response to a poster complaining about security through obscurity: security through obscurity is exactly the problem here. We use information like SSN and address which are not in any way secret, merely obscure, as a way to supposedly verify identity, and that's why we have so much identity theft. The reason no-one wants to post their SSN and address on Slashdot is precisely because security through obscurity sucks.

    9. Re:And now thanks to /. and microsoft by IsThisWorking · · Score: 5, Informative

      Security through obscurity is not about relying on secrecy of data, but about relying on secrecy of the algorithm or implementation. Those two things are different.

      If you do not make the distinction between data/information secrecy and design/algorithm/protocol/implementation secrecy, then you do not understand what security is.

    10. Re:And now thanks to /. and microsoft by rev_g33k_101 · · Score: 5, Funny

      The results are so haphazard, it feels like their parody of google is what actually drives Bing.

      I don't know how this late in the game a search engine can be so bad.

      answer:

      Because
      It's
      Not
      Google

      It's all in the name :D

      --
      "The problem with defending the purity of the English language is that English is about as pure as a cribhouse whore."
    11. Re:And now thanks to /. and microsoft by NekSnappa · · Score: 4, Funny

      Common man! This is /. so it has to be self-referencing
      Bing
      Is
      Not
      Google

      --
      I want to shoot the messenger!
  2. How does he know MS isn't doing anything else? by blankinthefill · · Score: 5, Insightful

    I'm curious how 'anonymous reader' knows that Microsoft is doing nothing to fix the problem. This has been bugging me for a long time. Its possible that a workable solution could take some time to get implemented, and in that time, doesn't it make sense to send a C&D letter in the interim? Hell, doesn't it make sense to send the letter anyways, so you don't have all these assholes trying to break your system? A C&D letter doesn't mean that other actions haven't been taken. Just a thought.

    1. Re:How does he know MS isn't doing anything else? by MadnessASAP · · Score: 4, Insightful

      Ever heard of the Streisand effect? If you're trying to suppress information about something a C&D is the last thing you want to do. Furthermore many companies when put in an identical situation will respond with "Thank you we are aware of the problem and are currently working on it" rather then a C&D.

      Also you sound like a schizophrenic jackass.

      --
      I may agree with what you say, but I will defend to the death your right to face the consequences of saying it.
    2. Re:How does he know MS isn't doing anything else? by Chrisq · · Score: 4, Insightful

      If they had any sense they would have anticipated the Streisand affect. It would have been much more effective to tell him the situation, ask him to remove the post and offer him whatever they paid their lawyers to issue the injunction as a "good will" gesture. That way if he did release it then he'd look like an @sshole rather than a victim.

    3. Re:How does he know MS isn't doing anything else? by neothoron · · Score: 5, Interesting

      Problem is, sending a C&D letter is doubly ineffective:

      • it barely has any effect in keeping potential exploiters from getting access to the vulnerability;
      • someone who cared enough about MS so that they could better themselves is treated like a nuisance (at best).

      In fact, compare that to the way the last TLS-related vulnerability was handled; in both cases, a critical flaw is revealed before a fix was ready. In the TLS case, it was handled with forthcoming and transparency. I'm not saying that MS should do the same (MS probably can't); but they would show more respect to Samir, and to all their bing cashback clients, by:

      • Ask Samir to remove most of the "sensible" post information - you know, instead of threaten with litigation from the get-go.
      • Take an official stance on that problem; what's the risk, who's affected, what should be done - instead of leaving bing cashback clients vulnerable to misinformation and abuse.
    4. Re:How does he know MS isn't doing anything else? by Anonymous Coward · · Score: 4, Insightful

      C&Ds do work in two cases:

      The first is if the C&D gets out fast enough that people are not unable to mirror the information, especially if it is stored in a dynamic database that can't just be grabbed completely with a wget. One example of this: Say someone makes a keygen app that runs on their webserver, and people submit forms to get bogus serial numbers. A C&D would completely smash this, preventing the information from getting released. Similar if people ran other services that could be nailed by an ACTA or DMCA takedown notice.

      The second is that the information that does escape the C&Ds gets pushed from mainstream sites to the seedy corners of the Internet. These are the same areas that have the dubious filesharing programs, the warez "search engines" and "DDL" sites [1], the "bump all Abloy locks in 2 secs, lulz" [2] text files, and other dodgy sites which tend to be more of a test of browser security than a place to find anything useful. So, unless someone is willing to spend time looking for that exact information on a hardened computer, it effectively has vanished.

      Don't underestimate the power of lawyers. They have the guys with guns on their side.

      [1]: I have DDL, or direct download in quotes because I have yet to personally see a usable direct download other than a Trojan or a drive by browser exploit in all my years of cleaning malware off of people's PCs who do believe in such fantasies.

      [2]: Yes, I know Abloy locks are unbumpable because of their design, but it is a good example. I don't know anything that defeats their latest PROTEC line of locks other than 12-14 hours of painstaking picking by dedicated speedpickers, or a good long session drilling the sucker out.

    5. Re:How does he know MS isn't doing anything else? by mister_playboy · · Score: 4, Interesting

      I wrote parking tickets as a job in college... very easy. My rule was to let people go if they showed up during the ticketing, which resolves every single confrontation in a positive way. If I had to call a tow truck on the car, I had to stand my ground, but only once did I encounter someone who showed up during the process and was a real dick about it.

      The parking services was second only to tuition and the football team in amount of revenue generated for the school. If anything, I could write more tickets by letting the few people I encountered during my work go and moving on to the 98% of cars whose owners don't show up rather than wasting 20 minutes arguing with each of them.

      Easily the least stressful job I've ever had.

      --
      Do what thou wilt shall be the whole of the Law ::: Love is the law, love under will
  3. Mirror by Rufus211 · · Score: 4, Informative

    Ive never bought anything using Bing Cashback, but the balance of my account is $2080.06. Apparently, I placed two $1 orders on January 24th of this year, and spent another $104,000 on October 24th. Lets see how these transactions might have accidentally got credited to my account.

    First, we need to try to figure out how transactions get into Bing Cashback. Microsoft posted some documentation here. The explanation of how a merchant reports transactions to Bing starts on page 20. Merchants have a few options for reporting, but Bing suggests using a tracking pixel. Basically, the merchant adds a tracking pixel to their order confirmation page, which will report the the transaction details back to Bing. The request for the tracking pixel looks something like this:

    https://ssl.search.live.com/cashback/pixel/index? jftid=0&jfoid=<orderid>&jfmid=<merchantid> &m[0]=<itemid>&p[0]=<price>&q[0]=<quantity>

    This implementation, while easy for the merchant, has an obvious flaw. Anyone can simulate the tracking pixel requests, and post fake transactions to Bing. Im not going to explain exactly how to generate the fake requests so that they actually post, but its not complicated. Bing doesnt seem to be able to detect these fake transactions, at least not right away. The six cents I earned in January have cleared, and Im guessing the remaining $2080 will clear on schedule, unless there is some manual intervention.

    Even if Bing detects these fake transactions at some point in the future, the current implementation might have another interesting side effect. I havent done enough work to say it with confidence, but a malicious user might be able to block another users legitimate purchases from being reported correctly by Bing (I only tried this once, but it seemed to work). Posting a transaction to Bing requires sending them an order ID in the request. Bing performs a reasonable sanity check on the order ID, and will not post a transaction that repeats a previously reported order ID. When a store uses predictable order IDs (e.g. sequential), a malicious user can use up all the future order IDs, and cause legitimate transactions to be ignored. Reporting would be effectively down for days, causing a customer service nightmare for both Bing and the merchant.

    Based on what Ive found, I wouldn't implement Bing Cashback if I were a merchant. And, as an end user and bargain hunter, it does not seem smart to rely on Bing Cashback for savings. In our next blog post, Ill demonstrate some other subtle but important reasons to avoid using Bing Cashback.

    It seems like people have still not learned to never trust anything from the user. This reminds me of some trivially exploitable web merchants years ago. The would store the entire shopping basket, including prices, in the user's cookies. User simply modifies their cookies so that everything costs $1 or $0.01 and they could order a dozen cpus / t-shirts / whatever for a few bucks.

    1. Re:Mirror by Rufus211 · · Score: 5, Insightful

      Also the guy who posted this is an idiot for placing a $100,000 transaction which would result in a $2,000 payment, and then bragging about it. His two $1 transactions proved the vulnerability and the $0.06 payment generated is easily ignored. The $100k transaction with $2k payment is just flat out wire fraud asking for federal PMITA prison.

    2. Re:Mirror by slimjim8094 · · Score: 4, Insightful

      Parent is not a troll. This guy is seriously in for it - the FBI et.al frowns upon people who cheat companies out of literally thousands of dollars. The six cents would've been overlooked, and prove the point nicely.

      $2k will certainly not be overlooked. Even if he never collects it... he's still fucked.

      --
      I have developed a truly marvelous proof of this comment, which this signature is too narrow to contain.
    3. Re:Mirror by TheWizardTim · · Score: 5, Funny

      Another fun trick was to take a $1 and a $20 and cut them both in half. Then tape half of the $1 and the $20 to make two $21 dollar bills. Silly I know, but if you put them in a change machine, it would look for the numbers in the corners, it would read a 20 then a 1 and then give you $21 in change. You then took the other part and got $21 in change as well. Quick way to double your money. Now the machines check to make sure that all four numbers on the corners match up.

    4. Re:Mirror by jrumney · · Score: 4, Insightful

      it would read a 20 then a 1 and then give you $21 in change.

      Sounds like an urban myth to me. Would it add 20 and 20 from the corners of a normal $20 bill and give you $40 change?

  4. Most entertaining... by netpixie · · Score: 5, Informative

    is the line from the letter

    "cease and desist the posting in any location of the material and information contained in this post"

    Seeing as it is their SDK that contains the details of this "feature", are they going to send themselves a C&D and then pull the SDK?

  5. No by oGMo · · Score: 5, Insightful

    If you have a glaring vulnerability that lets people defraud your customers out of arbitrary amounts of money, the only sane thing to do is immediately disable the feature. Not wait for a solution. Not cover up the issue. You make coverage of the issue irrelevant. If one person figured it out and wrote about it, 100 other people also figured it out and are using it for personal gain.

    --

    Don't think of it as a flame---it's more like an argument that does 3d6 fire damage

  6. It's called fraud by cookd · · Score: 5, Insightful

    This is called "fraud". Look it up. It's been around for a long time, a lot longer than HTTP. There are standard business practices for dealing with it. Not all of them are technical. This system's technical defenses are probably sufficient to raise an alarm (delayed by a few weeks as the results are collated), and it will produce a pretty good paper trail leading to the owner of the Bing account. Some of the systems take into account minor details such as the existence of accountants, a police force, a paper trail, and a legal system. Obviously some stronger technical measures might have made it a bit more difficult to pull off this partucular fraud, or maybe it might have even stopped it, but the non-technical measures will also work just fine if they are called into play.

    Whether or not the door is obviously guarded, it's still illegal to steal stuff from a store. The fact that the door was not protected with the latest and greatest in RFID theft detection systems doesn't change the fact that what you are doing is illegal. And perhaps the tracking process is slower than what you see in movies, people still get tracked down and arrested, days or weeks after the event. Moving from the streets onto the Internet doesn't really change the rules much (except that your case will probably wind up with Federal jurisdiction).

    In this case, the poor "hacker" (I wish him/her luck!) appears to have done the following:
    1. Used a specially formatted HTTP request to get a small fabricated purchase to show up as credited to his/her Bing account.
    2. Noticed that the cash back did show up with no problem as "available for withdrawal".
    3. Tried again with a much larger purchase. Again the purchase shows up in his account.
    4. Hacker is hoping that the amount will soon become available for withdrawal.

    On the other side of the world, the accounting systems for Microsoft and the associated merchant have likely compared invoices and noticed the discrepancies. The small ones got noted, but they were thrown out as "somebody is playing with the system, but it's not worth dealing with it". But this month, when going over the books, they're going to find a nice big 100,000 item that doesn't match up with any purchase recorded on the store's official records. However, they do have the account number of the buyer that should be getting the cash back. I'm not sure what typically happens at this point, but it probably involves cancelling dinner for the wolf pack so that by the time they're ready to send out the posse, the wolves are hungry.

    In this case, Microsoft has apparently (I haven't looked into this) provided an API by which a store can report a sale and attribute the sale to a particular Bing account. The API has varying levels of security, depending on how much effort the store wants to put into preventing fake transactions from entering the system. Low effort might be fine and takes less time to set up, but it's easier to attack and that means more work to do when reconciling the accounts. Just like many other mechanisms for quickly distributing non-critical information between merchants, this isn't meant to be the authoritative information transmission system, just a way for people to keep status on accounts in between the regularly-scheduled account reconciliations. This way Bing can update your account balance within seconds of the purchase. Of course, the payback won't happen until they've gone back and checked Microsoft's records against the merchant's records and pulled out any differences. The differences go to the auditor and possibly to the police or FBI.

    Could we maybe just think for a second before acting like jerks? Being a jerk means everybody suffers. I mean, just because I see a way to deface somebody's website doesn't mean I am obligated to do so. I walk by 100 cars a day, and I could easily spray shaving cream all over them and not get caught. But if everybody did that, quality of life would go down for everybody. Same thing on the internet.

    I hate this attitude out there th

    --
    Time flies like an arrow. Fruit flies like a banana.