Into the symmetry

tl;dr Mozilla Firefox prior to version 72 suffers from Small Subgroups Key Recovery Attack on DH in the WebCrypto 's API. The Firefox's team fixed the issue r emoving completely support for DH over finite fields (that is not in the WebCrypto standard). If you find this interesting read further below. Premise In this blog post I assume you are already knowledgeable about Diffie-Hellman over finite fields and related attacks. If not I recommend to read any cryptography book that covers public key cryptography. Here is a really cool simple explanation by David Wong : I found a cooler way to explain Diffie-Hellman :D pic.twitter.com/DlPvGwZbto — David Wong (@cryptodavidw) January 4, 2020 If you want more details about Small Subgroups Key Recovery Attack on DH I covered some background in one of my previous post ( OpenSSL Key Recovery Attack on DH small subgroups (CVE-2016-0701) ). There is also an academic pape r where we examine the issue with some more rigors. ...

Last Google Chrome release for Chrome 50.0.2661.75 contains the fix for a security low bug I found (CVE-2016-1658). When first I found this bug I was under the impression it could be an UXSS. Quickly after I reported I started to realize that this wasn't as exploitable though. The issue per se was extremely easy to reproduce: Create an HTML file that looks like and save it (e.g. chrome.html) <h1>Hi</h1>  <script> alert(document.domain)</script> Now supposing the file is saved under (in MacOS) /Users/xxx/Downloads/chrome.html open the file from hard disk in this way:   file://mail.google.com/Users/xxx/Downloads/chrome.html   Note: mail.google.com is arbitrary . This can be any domain (hence is universal)  Observe the document.domain alerted is mail.google.com!  Observe the cookies transported are the one associated with *.google.com domain : Now this looked really weird to me and I reported as an...

tl;dr Apple Safari for OS X was prone to URI spoofing vulnerability  (and more general a user interface spoofing). Apple released security updates for Safari 9 on OS X and assigned CVE-2015-5764. Accidentally this vulnerability was also present in iOS. Instant demo In Safari up to 8.0.8 : go to https://asanso.github.io/CVE-2015-5764/file0.html click "click me!" notice the address bar being "data:text/html,%3CH1%3EHi!!%3C/H1%3E" go back using the browser button click "click me!" notice the address bar being http://www.intothesymmetry.com/CVE-2015-5764/file0.php !!!!  Well this looks a clear caching problem to me, right :) ? The Introduction (Oldie but goldie) Several months ago (almost a year!!) I was reading the great book written by lcamtuf (aka Michal Zalewski) named The Tangled Web .  I know, I know I was a bit late for the party :) Said that, this book contained a really interesting Chapter (for the record Chapter 10) that is de...

Damien Antipa and me love browser security. Hence we always keep up to date on what is going on this field. Few months ago Christian Schneider blogged about Chrome SOP Bypass with SVG . We decided to poke some other browser using the same technique and the outcome was CVE-2015-3753 . The SOP-bypass for images works with Safari up to 8.0.7 We were able indeed to bypass the SOP for images served with 302 and with the data protocol (e.g. data:image/png;base64) and exfiltrate the image. You can find the detail of the issue in the mentioned blog post from Christian (our attack did not make use of the browser cache though) Step to reproduce with Safari 8.0.7 : Open the attacker page http://asanso.github.io/test. html username/password of the contained image are sop/sop - click "exploit step 1" (this is just an intermediate step to load the image) - click "exploit step 2" and appreciate the exfiltrated image in the alert message (substring) and the fu...