Services A, B and C belong to Service Inventory A.
Services D, E and F belong to Service Inventory B.
Service C acts as an authentication broker for Service Inventory A.
Service F acts as an authentication broker for Service Inventory B.
Both of the authentication brokers use Kerberos-based authentication technologies. Upon receiving a request message from a service consumer, Services C and F authenticate the request using a local identity store and then use a separate Ticket Granting Service (not shown) to issue the Kerberos ticket to the service consumer.

A recent security audit of the two service inventories revealed that both authentication brokers have been victims of attacks. In Service Inventory A, the attacker has been intercepting and modifying the credential information sent by Service C (the ticket requester) to the Ticket Granting Service. As a result, the requests have been invalidated and incorrectly rejected by the Ticket Granting Service. In Service Inventory B, the attacker has been obtaining service consumer credentials and has used them to request and receive valid tickets from the Ticket Granting Service. The attacker has then used these tickets to enable malicious service consumers to gain access to other services within the service inventory.
How can the two service inventory security architectures be improved in order to counter these attacks?

• A. WS-SecureConversation can be used to secure the communication between the authentication broker and service consumers in Service Inventory A.
  This ensures that Services A and B will contact Service C to request a security context token that will be used to generates a session key for the encryption of the ticket submitted to Service C.
  The Data Origin Authentication pattern can be applied to messages exchanged by services in Service Inventory B.
  This will ensure the integrity of messages try verifying their origins to the message recipients.
• B. The Data Confidentiality pattern can be applied to messages exchanged by the services in Service Inventory A.
  The Data Origin Authentication pattern can be applied to messages exchanged by services in Service Inventory B.
• C. WS-Trust can be used to establish secure communication between the authentication broker and the service consumers. After receiving the request message and the corresponding credentials from service consumers, the authentication broker can validate their identity, and if successful, a signed SAML assertion containing all authentication information will be issued. The SAML assertion will then be used to authenticate the service consumers during subsequent communications. Because the messages are signed and encrypted, malicious service consumers cannot access the data. This approach can be applied to counter the threats in both Service Inventories A and B.
• D. The Service Perimeter Guard pattern can be applied to Service Inventory A in order to establish a perimeter service responsible for validating and filtering all incoming request messages on behalf of Service C.
  The Data Origin Authentication pattern can be applied to messages exchanged by services in Service Inventory B.
  This will ensure the integrity of messages by verifying their origins to the message recipients.

Service Consumer A sends a request to Service A (1). Service A replies with an acknowledgement message (2) and then processes the request and sends a request message to Service B (3). This message contains confidential financial data. Service B sends three different request messages together with its security credentials to Services C.
D.
and E (4, 5, 6). Upon successful authentication, Services C.
D. and E store the data from the message in separate databases (7.8, 9). Services B.
C.D, and E belong to Service Inventory A, which further belongs to Organization B.
Service Consumer A and Service A belong to Organization A.

Organization B decides to create a new service inventory (Service Inventory B) for services that handle confidential data. Access to these services is restricted by allocating Service Inventory B its own private network. Access to this private network is further restricted by a dedicated firewall. Services C, D and E are moved into Service Inventory B, and as a result. Service B can no longer directly access these services.
How can this architecture be changed to allow Service B to access Services C, D and E in a manner that does not jeopardize the security of Service Inventory B while also having a minimal impact on the service composition's performance?

• A. The Service Perimeter Guard pattern is applied together with the Message Screening pattern. A new perimeter service is created specifically for Service Inventory B.
  This service filters all messages before they reach the firewall and further evaluates the IP address of the messages to verify the identity of the message originators. If the originator is successfully authenticated, then the perimeter guard checks the request message for potentially malicious content. If the request message does not contain malicious content, it is sent through the firewall to proceed to Services C, D, and E for further processing.
• B. The Data Confidentiality pattern is applied together with the Direct Authentication pattern. A new utility service is created to validate request messages sent to Service Inventory B.
  Service B must encrypt the message content using the utility service's public key and attach its own digital certificate to the request message. This message is first evaluated by the firewall to filter out requests from disallowed sources and can then be forwarded to the utility service, which then verifies the identity of the message originator (using a digital certificate) and decrypts the request message contents. If the originator is authorized to access Services C, D, and E, the appropriate request messages are sent to these services.
• C. The Brokered Authentication pattern is applied by extending the firewall functionality with a single sign-on mechanism. Because the firewall already restricts accesses to Service Inventory B, adding authentication logic to the firewall optimizes the performance of the overall security architecture. Service B needs to be authenticated by the authentication broker only once in order to get a security token that can be used to access Services C, D, and E.
  This eliminates the need for Service B to authenticate several times during the same service composition.
• D. The Service Perimeter Guard pattern is applied together with the Brokered Authentication pattern. A new perimeter service is created to intercept all request messages sent to services inside the private network (inside Service Inventory B), before they reach the firewall. The perimeter service also acts as the authentication broker that authenticates request messages sent to Services C, D, and E by evaluating the accompanying security credentials and issuing a security token to be used by Service B when accessing Services C, D, and E.