Improving Web Application Security: Threats and - CGISecurity

380 Part III: Building Secure Web ApplicationsProtect the Credentials for SQL AuthenticationIf you must use SQL authentication, be sure that the credentials are not sent over thenetwork in clear text and encrypt the database connection string because it containscredentials.To enable SQL Server to automatically encrypt credentials sent over the network,install a server certificate on the database server. Alternatively, use an IPSecencrypted channel between the Web and database servers to secure all traffic sent toand from the database server. To secure the connection string, use DPAPI. For moreinformation, see “Secure Your Connection String” in the “ConfigurationManagement” section, later in this chapter.Connect Using a Least Privileged AccountYour application should connect to the database by using a least privileged account.If you use Windows authentication to connect, the Windows account should be leastprivileged from an operating system perspective and should have limited privilegesand limited ability to access Windows resources. Additionally, whether or not youuse Windows authentication or SQL authentication, the corresponding SQL Serverlogin should be restricted by permissions in the database.For more information about how to create a least privileged database account andthe options for connecting an ASP.NET Web application to a remote database usingWindows authentication, see “Data Access” in Chapter 19, “Securing Your ASP.NETApplication and Web Services.”AuthorizationThe authorization process establishes if a user can retrieve and manipulate specificdata. There are two approaches: your data access code can use authorization todetermine whether or not to perform the requested operation, and the database canperform authorization to restrict the capabilities of the SQL login used by yourapplication.With inadequate authorization, a user may be able to see the data of another user andan unauthorized user may be able to access restricted data. To address these threats:● Restrict unauthorized callers.●●Restrict unauthorized code.Restrict the application in the database.