Wei Xu is a malware research engineer in Palo Alto Networks. He received his B.S. degree and M.S. degree in Eletrical Engineering from Tsinghua University, Beijing, China, in 2005 and 2007 respectively. His research interests include Web security, online privacy protection and smartphone security. Currently, he is working on the detection of malicious documents and the analysis of permission usage in Android apps. His past research projects include the early detection of worm propagation in online social networks and the detection of obfuscated malicious JavaScript code in Web pages.