Alex Ionescu

Alex is coauthor of Windows Internals 5th edition and is currently working on the 6th Edition. He teaches Windows OS internals to Microsoft employees and other security and government organizations worldwide through David Solomon Expert Seminars as well as his own company, Winsider Seminars & Solutions Inc., which also produces low-level system tools. He has also had the chance to contribute to some of Mark Russinovich's Sysinternals tools, such as Process Explorer. He is also 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 and Recon. Previously, Alex was the lead kernel developer for ReactOS, an open source clone of Windows XP/2003 written from scratch, where he wrote most of the NT-based kernel. In the last four years, he has also contributed to patches and development in two major commercially used operating system kernels.