Real-Life Example of a 'Business Logic Defect'

Sunday, March 13, 2011

Rafal Los

0a8cae998f9c51e3b3c0ccbaddf521aa

NOTE: This is just an example, this site is NOT the actual site vulnerable to this issue ... I know better...

Sometimes, curiosity just gets the best of me.

For example, I saw a site the other day, and I wanted to buy more than the site offered me at one given purchase.  This troubled me, because I didn't want to make separate purchases... so I set the hamster loose on the wheel and tried something interesting that should never have worked. 

This type of vulnerability is a manipulation of application business logic (at least our definition of it) and again, should never, ever work.

Except that it does, way more often than it should.

Tickets_Drop_Down1.jpg

So... again, I'm a curious sort, and I wondered, how would the back-end application logic behave if I simply modified the data that was sent to me.  I'm not sending any attack strings or anything obviously malicious, so it's not setting off any alarms...

3-1-2011 12-29-32 AM.jpg

Then... I simply made a small modification.  Again, I repeat - this is not the actual site/code that was vulnerable so stop Googling already.  I took one more screen shot before I clicked "Add to Cart" and performed a check out... mouth agape.

3-1-2011 12-32-18 AM.jpg

I win.  Logic fail.

Wouldn't it be really interesting if there was an automated way to start testing for these types of application logic defects in code out there? Hrmm...

Cross-posted from Following the White Rabbit

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