Minimizing SSO Effort in Verifying SSL Anti-phishing Indicators

摘要

In an on-line transaction, a user sends her personal sensitive data (e.g., password) to a server for authentication. This process is known as Single Sign-On (SSO). Subject to phishing and pharming attacks, the sensitive data may be disclosed to an adversary when the user is allured to visit a bogus server. There has been much research in anti-phishing methods and most of them are based on enhancing the security of browser indicator. In this paper, we present a completely different approach of defeating phishing and pharming attacks. Our method is based on encrypted cookie. It tags the sensitive data with the server's public key and stores it as a cookie on the user's machine. When the user visits the server so as to perform an online transaction, the sensitive data in the cookie will be encrypted with the stored public key of the server. The ciphertext can only be decrypted by the genuine server. Our encrypted cookie scheme (ECS) has the advantage that the user can ignore SSL indicator in the transaction process. The security is guaranteed even if the user accepts a malicious self-signed certificate. This advantage greatly releases user's burden of checking SSL indicator, which could be very difficult even for an experienced user when the phishing attacks have sophisticated vision design.