Alex Ionescu

Alex Ionescu is the founder of Winsider Seminars & Solutions Inc., specializing in low-level system software for administrators and developers as well as reverse engineering and security trainings for government intelligence and defence agencies; he also teaches Windows internals courses for David Solomon Expert Seminars, notably at Microsoft. He is coauthor of the Windows Internals series (since the 5th Edition), along with Mark Russinovich and David Solomon.

From 2003-2007, Alex was the lead kernel developer for ReactOS, an open source clone of Windows XP/Server 2003 written from scratch, for which he wrote most of the Windows NT–based kernel. From 2007-2011 Alex worked part-time at Apple (and as an intern between summers) on the iOS kernel, boot loader, firmware, and drivers on the original core platform team behind the iPhone, iPad and AppleTV. Returning to his Windows security roots, Alex is now Chief Architect at a Seattle and San Francisco-based startup still under stealth.

Alex continues to be very active in the security research community, discovering and reporting several vulnerabilities related to the Windows kernel and presenting talks at conferences such as Blackhat, SyScan, and Recon. His work has led to the fixing of many critical kernel vulnerabilities, as well as to over a few dozen non-security bugs.