Author - Ylabs

Merry Hackmas: multiple vulnerabilities in MSI’s products

This blog post serves as an advisory for a couple MSI’s products that are affected by multiple high-severity vulnerabilities in the driver components they are shipped with. All the vulnerabilities are triggered by sending specific IOCTL requests and will allow to: Directly interact with physical memory via the MmMapIoSpace function call, mapping physical memory into a...

Driver Buddy Reloaded

As part of Yarix's continuous security research journey, during this year I’ve spent a good amount of time reverse-engineering Windows drivers and exploiting kernel-mode related vulnerabilities. While in the past there were (as far as I know), at least two good IDA plugins aiding in the reverse engineering process: DriverBuddy of NCC Group. ...

Crucial’s MOD Utility LPE – CVE-2021-41285

Crucial Ballistix MOD Utility is a software product that can be used to customize and control gaming systems, specifically LED colours and patterns, memory, temperature, and overclock.During my vulnerability research, I’ve discovered that this software utilizes a driver, MODAPI.sys, containing multiple vulnerabilities and allowing an attacker to achieve local privilege escalation from...

Homemade Fuzzing Platform Recipe

It’s no secret that, since the beginning of the year, I’ve spent a good amount of time learning how to fuzz different Windows software, triaging crashes, filling CVE forms, writing harnesses and custom tools to aid in the process.Today I would like to sneak peek into my high-level process of designing a Homemade Fuzzing Platform,...

Reverse Engineering & Exploiting Dell CVE-2021-21551

At the beginning of the month, Sentinel One disclosed five high severity vulnerabilities in Dell’s firmware update driver.As the described vulnerability appeared not too complicated to exploit, a lot of fellow security researchers started weaponizing it. I was one of, if not the first tweeting about weaponizing it into a _SEP_TOKEN_PRIVILEGES overwrite...

Chaining Bugs: NVIDIA GeForce Experience (GFE) Command Execution

NVIDIA GeForce Experience (GFE) v.<= 3.21 is affected by an Arbitrary File Write vulnerability in the GameStream/ShadowPlay plugins, where log files are created using NT AUTHORITY\SYSTEM level permissions, which lead to Command Execution and Elevation of Privileges (EoP). NVIDIA Security Bulletin – April 2021 NVIDIA Acknowledgements Page

Introduction

Some time ago I was looking for...

Malware Analysis: Ragnarok Ransomware

The analysed sample is a malware employed by the Threat Actor known as Ragnarok. The ransomware is responsible for files’ encryption and it is typically executed, by the actors themselves, on the compromised machines. The name of the analysed executable is xs_high.exe, but others have been found used by the same ransomware family (such as...

Fuzzing: FastStone Image Viewer & CVE-2021-26236

Introduction

In my precedent blog post I’ve introduced “fuzzing” from a theoretical point of view. As I’ve previously anticipated, today I’m going to disclose the fuzzing methodology, process and samples that led me to discover five different vulnerabilities in FastStone Image Viewer v.<=7.5. I’ll also go over the root cause analysis of CVE-2021-26236...