A Survey on CAPTCHA as Graphical Password

There are various challenges to be faced to provide security to Web applications. To reach the backend problems attackers use information that is not validated before by any Web applications. Unauthorized functions are used to access to other accounts. There are various injection flaws in which malicious commands are embedded in parameters and the external system executes the commands accordingly on behalf of the Web application. Improper coding results in weak protection of web applications that use cryptographic functions to protect information and credentials. Thus, in various ways access to the Web application is provided with security. Applications are such that they are robust against input data of all forms be it user, database or any other external entity. CAPTCHA stand for Completely Automated Public Turning Test to Tell Computers and Humans. It is a test that authenticated users have to pass the test to gain access to their respective mail accounts. Malicious programs like bots, attack the accounts that are a threat to the data integrity, privacy, and confidentiality. To avoid this, CAPTCHA was introduced. Here all type of CAPTCHA and their drawbacks are going to describe.