Improving Web Application Security: Threats and - CGISecurity

Chapter 11: Building Secure Serviced Components 3135. The code checks whether or not security is enabled prior to the explicit role check.This is a risk mitigation strategy to ensure that transactions cannot be performed ifthe application security configuration is inadvertently or deliberately disabled byan administrator.Note The IsCallerInRole method always returns “true” if security is disabled.6. Callers must be members of either the Manager or Senior Manager role because ofthe declarative security used on the method. For fine-grained authorization, therole membership of the caller is explicitly checked in code.7. The transaction is audited.8. The audit implementation obtains the identity of the original caller by using theSecurityCallContext object.Code Access Security ConsiderationsApplications that use serviced components are usually fully trusted and, as a result,code access security has limited use to authorize calling code. The calling code shouldconsider the following points:● Unmanaged code permission is required to activate and perform cross contextcalls on serviced components.● If the client of a serviced component is an ASP.NET Web application, then its trustlevel must be set to “Full” as shown below.●If your Web application is configured with a trust level other than “Full,” it doesnot have the unmanaged code permission. In this instance, you must create asandboxed wrapper assembly to encapsulate the communication with the servicedcomponent. You must also configure code access security policy to grant thewrapper assembly the unmanaged code permission. For more information aboutthe sandboxing technique used to encapsulate high privileged code, see Chapter 9,“Using Code Access Security with ASP.NET.”If a reference to a serviced component is passed to untrusted code, methodsdefined on the serviced component cannot be called from the untrusted code.The exception to this rule is with methods than do not require context switching orinterception services and do not call members of System.EnterpriseServices. Suchmethods can be called by untrusted code.