Improving Web Application Security: Threats and - CGISecurity

372 Part III: Building Secure Web ApplicationsCountermeasuresTo prevent unauthorized access:● Use principal permission demands to authorize the calling user.● Use code access security permission demands to authorize the calling code.●Use limited permissions to restrict the application’s login to the database and toprevent direct table access.Network EavesdroppingThe deployment architecture of most applications includes a physical separation ofthe data access code from the database server. As a result, sensitive data such asapplication-specific data or database login credentials must be protected fromnetwork eavesdroppers.VulnerabilitiesThe following practices increase vulnerability to network eavesdropping:● Clear text credentials passed over the network during SQL authentication● Unencrypted sensitive application data sent to and from the database serverCountermeasuresTo limit vulnerability to network eavesdropping:● Use Windows authentication to avoid sending credentials over the network.● Install a server certificate on the database server. This results in the automaticencryption of SQL credentials over the network.● Use an SSL connection between the Web server and database server to protectsensitive application data. This requires a database server certificate.● Use an IPSec encrypted channel between Web and database server.Design ConsiderationsBefore you start writing code, there are a number of important issues to consider atdesign time. The key considerations are:● Use Windows authentication.●●●●Use least privileged accounts.Use stored procedures.Protect sensitive data in storage.Use separate data access assemblies.