I buy and listen to this person's lectures every time they come out. 

They're so good!

hyeonseok985238

This lecture covers the king of client attacks, XSS (Cross-Site Scripting). You can systematically learn about the basic concepts of XSS, the attack principles, and most importantly, what process to go through to perform the attack procedure.

crehacktive

XSS attack techniques explained by a mock hacking practitioner

입문

초급

중급이상

Penetration Testing

Education Prologue

Understanding XSS Attacks

Understanding JavaScript for XSS Attacks

Detailed analysis of attack techniques and attack principles

Attack Detail Methodology

Various bypass techniques according to verification logic

Understanding the principles of session hijacking attacks and practicing attacks

Understanding the principles of keylogging attacks and practicing attacks

Precautions when conducting a practical diagnosis

Countermeasures