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. ...

tl;dr https://sites.google.com suffered from a Billion Laugh Attack vulnerability that made the containerized environment to crash with a single invocation. Introduction Few months ago I applied for a talk at a security conference titled So you wanna be a Bug Bounty Hunter but it was rejected :( . The reason behind it is that I have been on/off in the bug bounty business for a while as you can see here: Funny. Found in a forgotten drawer from the time I was a bug hunter :p #facebook #bug #bounty pic.twitter.com/Tt4saGZVLI — Antonio Sanso (@asanso) November 30, 2018 and I would have liked to share some of the things I have learned during th e se years (not necessary technical advises only). You can find a couple of these advises here: Rule #1 of any bug hunter is to have a good RSS feed list and here :  The rule #2 of any bug hunter is to DO NOT be to fussy with 'food' specifically with "left over" Today's rule is: The rule #3 of...

tl;dr in this blog post I am going to talk about some bug bounty left over with a little rant. Here you can find bug bounty left over part I and II Here you can find bug bounty rant part I and II Introduction In one of my previous post I was saying that:    "The rule #1 of any bug hunter... is to have a good RSS feed list."   Well well well allow me in this post to state rule #2 (IMHO) "The rule #2 of any bug hunter is to DO NOT be to fussy with 'food' specifically with left over" aka even if the most experience bug hunter was there (and it definitely was my case here, given the fact we are talking about no one less than filedescriptor ) do not assume that all the vulnerabilities have been found! So if you want some examples here we go.   Part I - Google I have the privilege to receive from time to time Google Vulnerability Research Grant . One of the last I received had many target options to choose from, but one in particular caught my...

tl;dr Firefox and Java suffered from a moderate vulnerability affecting the elliptic curve point addition algorithm that uses mixed Jacobian-affine coordinates where it can yield a result POINT_AT_INFINITY when it should not. Introduction Few months ago I was working on a vulnerability affecting the internet standard JWE (slides here ) and I got a stroke of luck . Yuppieeee  Basically I was constructing the malicious JWEs needed for the Demo Attack . When something weird happened :S You can try and share with me the surprise I had, the gist is here If you try to execute this class with Java 1.7 you basically have Exception in thread "main" java.lang.IllegalStateException     at sun.security.ec.ECDHKeyAgreement.deriveKey(Native Method)     at sun.security.ec.ECDHKeyAgreement.engineGenerateSecret(ECDHKeyAgreement.java:130)     at javax.crypto.KeyAgreement.generateSecret(KeyAgreement.java:586)     at orig...

tl;dr if you are using go-jose , node-jose , jose2go , Nimbus JOSE+JWT or jose4j with ECDH-ES please update to the latest version. RFC 7516 aka JSON Web Encryption (JWE) hence many software libraries implementing this specification used to suffer from a classic Invalid Curve Attack . This would allow an attacker to completely recover the secret key of a party using JWE with Key Agreement with Elliptic Curve Diffie-Hellman Ephemeral Static (ECDH-ES) , where the sender could extract receiver’s private key. Premise In this blog post I assume you are already knowledgeable about elliptic curves and their use in cryptography. If not Nick Sullivan 's A (Relatively Easy To Understand) Primer on Elliptic Curve Cryptography or Andrea Corbellini's series Elliptic Curve Cryptography: finite fields and discrete logarithms are great starting points. Then if you further want to climb the elliptic learning curve including the related attacks you might also want to visit https://s...

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...