full-disclosure - Re: Denial of Service in WordPress

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Message-ID: <CALx_OUA=Qu_t2KBntSOj=W7Z3N9-H48RN0bvmRx7seVLxfkmCw@mail.gmail.com>
Date: Sat, 29 Jun 2013 11:03:45 -0700
From: Michal Zalewski <lcamtuf@...edump.cx>
To: MustLive <mustlive@...security.com.ua>
Cc: full-disclosure@...ts.grok.org.uk
Subject: Re: Denial of Service in WordPress

> I.e. this is 21 times / infinite times more effective for attack.

Not really, in terms of the bandwidth you can use up / the number of
requests you can create. You're essentially trading this:

for (var i = 0; i < whatever; i++) {
   var x = new XMLHttpRequest(); /* or new Image() or whatever */
   ...
}

...for this:

for (var i = 0; i < whatever / redirect_limit; i++) {
  for (var j = 0; j < redirect_limit; j++) { /* implicit loop */
    ...
  }
}

...and it shouldn't matter.

You can generate a ton of expensive traffic from within JS these days.

/mz

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