Ryan "elfmaster" O'Neill is a computer security researcher and software engineer with a background in reverse engineering, software exploitation, security defense, and forensics technologies. He grew up in the computer hacker subculture, the world of EFnet, BBS systems, and remote buffer overflows on systems with an executable stack. He was introduced to system security, exploitation, and virus writing at a young age. His great passion for computer hacking has evolved into a love for software development and professional security research. Ryan has spoken at various computer security conferences, including DEFCON and RuxCon, and also conducts a 2-day ELF binary hacking workshop.

He has an extremely fulfilling career and has worked at great companies such as Pikewerks, Leviathan Security Group, and more recently Backtrace as a software engineer.

Ryan has not published any other books, but he is well known for some of his papers published in online journals such as Phrack and VXHeaven. Many of his other publications can be found on his website at http://www.bitlackeys.org.