Improving Web Application Security: Threats and - CGISecurity

558 Part IV: Securing Your Network, Host, and ApplicationDo Not Run ASP.NET as SYSTEMDo not use the SYSTEM account to run ASP.NET and do not grant the ASP.NETprocess account the “Act as part of the operating system” user right. Doing so defeatsthe principle of least privilege and increases the damage that can be done by anattacker who is able to execute code using the Web application’s process securitycontext.ImpersonationBy default, ASP.NET applications do not impersonate. The security context of theASP.NET worker process account (ASPNET by default) is used when yourapplication accesses Windows resources.The element is used to enable impersonation. You can impersonate:●●The original caller (the IIS authenticated identity)A fixed identityImpersonating the Original CallerTo impersonate the original caller, use the following configuration:The impersonation uses the access token provided by IIS that represents theauthenticated caller. This may be the anonymous Internet user account, for example,if your application uses Forms authentication, or it may be a Windows account thatrepresents the original caller, if your application uses Windows authentication.If you do enable original caller impersonation, note the following issues:● Application scalability is reduced because database connections cannot beeffectively pooled.● Administration effort increases as ACLs on back-end resources need to beconfigured for individual users.● Delegation requires Kerberos authentication and a suitably configuredWindows 2000 environment.For more information, see “How To: Implement Kerberos Delegation forWindows 2000” in the “How To” section of “Microsoft patterns & practices Volume I,Building Secure ASP.NET Applications: Authentication, Authorization, and SecureCommunication” at http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnnetsec/html/SecNetHT05.asp.