Portal site is not only providing search engine and e-mail service but also various services including blog, news, shopping, and others. The fact that average number of daily login for Korean portal site Naver is reaching 300 million suggests that many people are using portal sites. With the increase in number of users followed by the diversity in types of services provided by portal sites, the attack is also increasing. Most of studies of password authentication is focused on threat and

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... measures, however, in this study, we analyse the security threats and security requirement of membership, login, password reset first phase, password reset second phase. Also, we measure security score with common criteria of attack potential. As a result, we compare password authentication system of domestic and abroad portal sites.