Before revision:  Many existing studies show the vulnerabilities of machine learning and deep learning modelsagainst adversarial examples . {\em   However, most existing works currently focus on evasion attack on text data instead of positioning attack , also named backdoor attack .
After revision:  Many existing studies show the vulnerabilities of machine learning and deep learning modelsagainst adversarial examples . This raises the security threats of the released models. In addition to the clean models' unintentional weaknesses,{\em However, most existing works currently focus on evasion attack on text data instead of positioning attack , also named backdoor attack .