Proposal title : Practical exploitation of cryptographic flaws in Windows
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Session type: Talk round 2 (30 minutes)

Abstract:
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In their first Patch Tuesday of January 2020, Microsoft patched [CVE-2020-0601](https://research.kudelskisecurity.com/2020/01/15/cve-2020-0601-the-chainoffools-attack-explained-with-poc/), aka CurveBall, a flaw in their root CA trust store that allowed anybody to forge certificates that would be recognized as trusted by Windows 10 and Windows Server 2016/2019. The flaw was first discovered by the NSA and patched without fully disclosing its details.
Back then, we "reversed" it and released a POC within 48 hours of its non-disclosure. We'll see how.

More recently, a second flaw,[CVE-2022-34689](https://www.bleepingcomputer.com/news/security/exploit-released-for-critical-windows-cryptoapi-spoofing-bug/), was disclosed by the NSA in Windows CryptoAPI. It was patched in August 2022, but was only publicly announced in the October 2022 Patch Tuesday.

In this talk we will discover how to leverage such cryptographic flaws in order to create trusted, signed binaries or how they enable us to perform MITM attacks against unpatched Windows machines and servers!
We will also address how one can defend against these and why non-disclosure is not a great idea, especially for cryptographic flaws.

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Notes
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A previous version of this talk was accepted for NorthSec 2020 but because of COVID we were not able to make it. Even if this vulnerability dates from 2020 we think it has a big impact on the security community and worth a deep dive explanation.
Futhermore the fact that a new significant vulnerability was patched in the same component and also has available POC code means the CryptoAPI is a good target on unpatched systems even now.

We will introduce the notions required to understand the whole, but without going too much into the maths.

Notice that while the vulnerability was originally discovered by the NSA, they did not practice the usual responsible disclosure and fully disclosed the issue once it was patched. We had to dig into the patch to find what was going on and do a PoC to prove we found it. We were the first ones to release a working PoC on Github for it, along with a [blog post](https://research.kudelskisecurity.com/2020/01/15/cve-2020-0601-the-chainoffools-attack-explained-with-poc/) explaining the flaw.

We plan to release an updated PoC that would allow better exploitation, e.g. in the frame of a pentest than the current one, along with a MITM script working with it to ease the usage even further.

Additional Speaker: Sylvain Pelissier