Abstract: Network security is the condition of being protected against danger or loss. In the general sense, security is a concept similar to safety. This safety plays a vital role in bank transactions where disclosure of any data results in huge loss. In this paper, Various security threats are illustrated using a tree structure being root nodes as the threats and leaf nodes to achieve those threats and probable measures to overcome the same has been described. security of online bank transactions have been improved by increasing the number of bits used in establishing the SSL connection as well as in RSA asymmetric key encryption along with SHA1 used for digital signature to authenticate the client. Analysis and the results obtained will prove the improved security in proposed method.