Alex Ionescu is the Chief Architect at CrowdStrike, Inc. Alex is a world-class security architect and consultant expert in low-level system software, kernel development, security training, and reverse engineering. He is coauthor of the last two editions of the Windows Internals series, along with Mark Russinovich and David Solomon. His work has led to the fixing of many critical kernel vulnerabilities, as well as over a few dozen non-security bugs.

Previously, Alex was the lead kernel developer for ReactOS, an open source Windows clone written from scratch, for which he wrote most of the Windows NT-based subsystems. During his studies in Computer Science, Alex worked at Apple on the iOS kernel, boot loader, and drivers on the original core platform team behind the iPhone, iPad and AppleTV. Alex is also the founder of Winsider Seminars & Solutions Inc., a company that specializes in low- level system software, reverse engineering and security trainings for various institutions. In the last three years, he has also contributed to patches and development in two major commercially used operating system kernels.