(My) OWASP Belgium Chapter meeting notes

These are my notes of OWASP Belgium Chapter meeting of 19th of March.

KRACKing WPA2 in Practice Using Key Reinstallation Attacks (by Mathy Vanhoef)

This talk subject was about the attack on the WPA2 protocol that was made the (security) headlines last year. The original paper can be found here and the slides can  be found here.

The talk had 4 parts :

  • presentation of the attack.
  • practical impact
  • common misconceptions
  • lesson learned

 Presentation of the attack

The 4-way handshake is used in any WPA2 protected network. His use if for mutual authentication and to negotiate a new pairwise temporal key (PTK).

The messages sent between the client and the access point (AP) are the following ones:

 

The PTK is computed in the following way: PTK = Combine (shared secret, ANonce, SNonce) where ANonce, SNonce are random numbers.

Re-installation attack:

  • the attacker will clone the access point on different channel.
  • the attacker will/can forward or block frames.
  • the first 3 messages are sent back to client and AP.
  • message 4 is not sent to the AP; the attacker block this, and the client install the PTK (as per protocol specification)

  • client can sent encrypted data but the AP will try to recover from this by re-sending message 3.
  • then the client will reinstall the PTK meaning that will reset the nonce used to send encrypted data.

  • the effect of this key re-installation is that the attacker can decrypt the frames sent by the client.

Other types of handshake protocols are vulnerable to this kind of attack:

  • group key handshake.
  • fp handshake.

Practical impact of the attack

The main impact is that the attacker can decrypt the data frames sent by the victim to the AP (access point) and the attacker can replay frames sent to the victim.

  • iOS 10 and Windows, the 4-way handshake is not affected (because they are not following the WPA2 specification), but the group key handshake is affected.
  • Linux and Android 6.0+ that are using the wpa_supplicant 2.4+ version are exposed to install all-zero key vulnerability. The basic explanation of the vulnerability is the following one; the application do not keep the key, the PTK is installed at the kernel level and the application will zeroed the memory buffer that contains the key. But when the key re-installation is triggered, then the all-zero key will be sent to the kernel to be installed.

Countermeasures:

  • AP (access point) can prevent most of the attacks on clients:
    •  Don’t retransmit message 3/4.
    • Don’t retransmit group message 1/2.

Common missconceptions

  • update only the client or AP is sufficient.
    • in fact both vulnerable clients & vulnerable APs must apply patches
  • must be connected to network as attacker.
    • in fact the attacker only need to be nearby victim and network.

Lessons learned

4-way handshake proven secure AND encryption protocol proven secure BUT the combination of both of them was not proven secure.
This proves the limitation of formal proofs so abstract model ≠ real code.

Making the web secure by design (by Glenn Ten Cate and Riccardo Ten Cate)

This talk was about the new version of the OWASP SKF.  I already covered  the SKF in some of my previous tickets (see here and here) so for me was not really a novelty. The main changes that I was able to catch comparing with the previous version :

5 (software) security books that every (software) developer should read

I must admit that the title is a little bit catchy; a better title would have been “5 software security books that every developer should be aware of“. Depending on your interest you might want to read entirely these books or you could just know that they exists. There must be tons of software security books on the market but this is my short list of books about software security that I think that each developer that is interested in software security should be aware of.

Hacking – the art of exploitation This book explains the basics of different hacking techniques, especially the non-web hacking techniques: how to find vulnerabilities (and defend against)  like buffer overflow or stack-based buffer overflow , how to write shellcodes, some basic concepts on cryptography and attacks linked to the cryptography like the man-in-the-middle attack of an SSL connection. The author tried to make the text easy for non-technical peoples but some programming experience is required (ideally C/C++) in order to get the best of this book. You can see my full review of the book here.

Iron-Clad Java: Building secure web applications This book presents the hacking techniques and the countermeasures for the web applications; you can see this books as complementary of the previous one; the first one contains the non-web hacking techniques, this one contains (only) web hacking techniques; XSS, CSRF, how to protect data at rest, SQL injection and other types of injections attacks. In order to get the most of the book some Java knowledge is required. You can see my full review of the book here.

Software Security-Building security in  This books explains how to introduce the security into the SDLC; how to introduce abuse cases and security requirements in the requirements phase, how to introduce risk analysis (also known as Threat Modeling) in the design phase and software qualification phase. I really think that each software developer should at least read the first chapter of the book where the authors explains why the old way of securing application (seeing the software applications as “black boxes” than can be protected using firewalls and IDS/IPS) it cannot work anymore in the today software landscape. You can see my full review of the book here: Part 1, Part 2 and Part 3.

The Tangled Web: A Guide to Securing Modern Web Applications This is another technical book about security on which you will not see a single line of code (the Software Security-Building security in is another one) but it highly instructive especially if you are a web developer. The book presents all the “bricks” of the today Internet: HTTP, WWW, HTML, Cookies, Scripting languages, how these bricks are implemented in different browsers and especially how the browsers are implementing the security mechanism against rogue applications. You can see my full review of the book here.

Threat modeling – designing for security Threat modeling techniques (also known as Architectural Risk Analysis) were around for some time but what it has changed in the last years is the accessibility of these technique for the software developers.  This book is one of the reasons for which the threat modeling is accessible to the developers. The book is very dense but it  suppose that you have no knowledge about the subject. If you are interested in the threat modeling topic you can check this ticket: threat modeling for mere mortals.