A virtual journey: From hardware virtualization to Hyper-V's Virtual Trust Levels

A step by step approach to reverse engineer Hyper-V and have a low level insight into Virtual Trust Levels.

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Hello Rewind, meet world

How to perform snapshot-based coverage-guided fuzzing on Windows kernel components using Rewind, a tool we have just published on Github.

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Guided tour inside WinDefender’s network inspection driver

This article describes how Windows Defender implements its network inspection feature inside the kernel through the use of WFP (Windows Filtering Platform), how the device object’s security descriptor protects it from being exposed to potential vulnerabilities and details some bugs I found. As a complement to this post, a small utility is released to test the different bugs.

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Analysis of a Windows IPv6 Fragmentation Vulnerability: CVE-2021-24086

In this blog post we analyze a denial of service vulnerability affecting the IPv6 stack of Windows. This issue, whose root cause can be found in the mishandling of IPv6 fragments, was patched by Microsoft in their February 2021 security bulletin.

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How the MSVC Compiler Generates XFG Function Prototype Hashes

Microsoft is currently working on Xtended Flow Guard (XFG), an evolved version of Control Flow Guard (CFG), their own control flow integrity implementation. XFG works by restricting indirect control flow transfers based on type-based hashes of function prototypes. This blog post is a deep dive into how the MSVC compiler generates those XFG function prototype hashes.

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Beware the Bad Neighbor: Analysis and PoC of the Windows IPv6 Router Advertisement Vulnerability (CVE-2020-16898)

This blog post analyzes the vulnerability known as "Bad Neighbor" or CVE-2020-16898, a stack-based buffer overflow in the IPv6 stack of Windows, which can be remotely triggered by means of a malformed Router Advertisement packet.

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Playing with the Windows Notification Facility (WNF)

This blogpost briefly presents the Windows Notification Facility and provides a write-up for a nice exercise that was given by Bruce Dang during his workshop at Recon Montreal 2018.

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Reverse Engineering the Win32k Type Isolation Mitigation

Given the popularity of GDI Bitmap objects for exploitation of kernel vulnerabilities -due to the fact that almost any kind of memory corruption vulnerability (except for NULL-writes) could be used to reliably gain arbitrary R/W primitives over the kernel memory by abusing Bitmaps- Microsoft decided to kill exploitation techniques based on Bitmaps. In order to do this, Windows 10 Fall Creators Update (also known as Windows 10 1709) introduced the Type Isolation feature, an exploitation mitigation in the Win32k subsystem, which splits the memory layout of SURFACE objects, the internal representation of Bitmaps on the kernel side. This blogpost takes a deep dive into the details of how Type Isolation is implemented.

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Exploiting MS16-145: MS Edge TypedArray.sort Use-After-Free (CVE-2016-7288)

On February 9, 2017, Natalie Silvanovich from Google Project Zero unrestricted access to P0's issue #983 , titled "Microsoft Edge: Use-after-free in TypedArray.sort", which got assigned CVE-2016-7288 and was patched as part of Microsoft security bulletin MS16-145 during December 2016. In this blog post we discuss how I managed to exploit this UAF issue to obtain remote code execution on MS Edge.

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Analysis of MS16-104: .URL files Security Feature Bypass (CVE-2016-3353)

On September 13th, 2016 Microsoft released security bulletin MS16-104 , which addresses several vulnerabilities affecting Internet Explorer. One of those vulnerabilities is CVE-2016-3353, a security feature bypass bug in the way .URL files are handled. This security issue does not allow for remote code execution by itself; instead, it allows attackers to bypass a security warning in attacks involving user interaction. In this blogpost we discuss the whole process, from reverse engineering the patch to building a Proof-of-Concept for this vulnerability.

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