SQL Injection

               SELECT * FROM `login` WHERE `user`=‘test_user’ AND `pass`=‘test_passwd’

                

                    SELECT * FROM `login` WHERE `user`=‘’ OR ‘a’=‘a’ AND `pass`=‘’ OR ‘a’=‘a’ 
                     // 'a'='a' is always true, this query gets all the records from login table.
                    
                    SELECT * FROM `login` WHERE `user`=‘’; DROP TABLE `login`; --’ AND `pass`=‘’
                    //This query add DROP statment as multiple statement and drop the table 'login' in the database.
                   

• Adding the logic to allow only numbers / letters in username and password web page fields
• How should you enforce the constraint? SERVER SIDE.
• ‘ESCAPE’ bad characters.’ becomes \’
• Providing READ ONLY database access.
• Remember this is NOT just for login areas! NOT just for websites!