Online Access Free S90.20 Practice Test

Service A provides a customized report generating capability. Due to infrastructure limitations, the number of service consumers permitted to access Service A concurrently is strictly controlled. Service A validates request messages based on the supplied credentials (1). If the authentication of the request message is successful, Service A sends a message to Service B (2) to retrieve the required data from Database A (3). Service A stores the response from Service B (4) in memory and then issues a request message to Service C (5). Service C retrieves a different set of data from Database A (6) and sends the result back to Service A (7). Service A consolidates the data received from Services B and C and sends the generated report in the response message to the service consumer (8).

It has been discovered that attackers have been gaining access to confidential data exchanged between Service A and Service B, and between Service A and its service consumers. What changes can be made to this service composition architecture in order to counter this threat?

• A.Apply the Service Perimeter Guard pattern in order to protect message exchanges between Service A and its service consumers. Apply the Direct Authentication pattern in order to protect message exchanges between Service A and Service B.
• B.Apply the Direct Authentication pattern in order to protect message exchanges between Service A and its service consumers and between Service A and Service B.
  This approach will establish a password-based authentication mechanism that relies on a local identity store and will therefore prevent access by attackers.
• C.None of the above
• D.Apply the Data Origin Authentication pattern to protect the final report sent by Service A to its service consumer. Service A can generate a message digest of the final report, after which it can sign the digest with its own private key. It then can send both the final report and the signed message digest to its service consumer. This service consumer can generate its own message digest, decrypt the signed digest using the public key of Service A (which proves that Service A sent the message), and then compare the two digests. If the digests match, it guarantees that the final report was not tampered with during transmission.

• A.Apply the Service Perimeter Guard pattern together with the Trusted Subsystem pattern to establish a perimeter service that can perform security functions on behalf of Service A.
  The utility service can verify the validity of the request messages from Service Consumer A by authenticating the request message against an identity store. If the request message is authenticated, the utility service then sends it to Service A for further processing. All communications between Service A and Service Consumer A can be encrypted using the public key of the intended recipient, and signed using the private key of the sender.
  Industry standards that can be used for this solution are XML-Encryption, XML-Signature, and WS-Trust.
• B.Apply the Trusted Subsystem pattern together with the Data Origin Authentication pattern in order to establish a utility service that performs the security processing on behalf of Service A.
  Service Consumer A must digitally sign all request messages and encrypt the credential information using the public key of the utility service. The utility service can then verify the security credentials and the digital signature to establish the validity of the request message. If the request message is permitted, the utility service establishes a composite trust domain that encompasses Service Consumer A, Service A, Database A, and the legacy system. Because all communications remain within a single trust domain, malicious intermediaries will not be able to gain access to any exchanged data.
• C.Apply the Data Origin Authentication pattern together with the Data Confidentiality pattern in order to establish message-layer security that guarantees the confidentiality and integrity of messages exchanged by Service Consumer A and Service A.
  Further, a security policy can be created to require that security credentials submitted to Service A must be digitally signed and encrypted and also contain a timestamp to validate the actual time the request was issued. Industry standards that can be used for this solution are WS- Policy, WS-SecurityPolicy, XML-Encryption, and XML-Signature.
• D.Apply the Service Perimeter Guard pattern to establish a perimeter service that can perform security functions on behalf of Service A.
  Next, apply the Data Confidentiality pattern so that the security credential information provided by Service Consumer A with the request message is encrypted with the secret key shared between the perimeter service and Service Consumer A.
  The perimeter service evaluates the credentials and if successfully authenticated, forwards the request message to Service A.
  Transport-layer security is used to protect message exchanges between Service A and Service Consumer
• E.

• A.The database rules are changed so that the ID value of database records no longer needs to be unique. As a further precaution, the Service A logic is changed to disallow the update of private database records by service consumers with only public access permissions.
• B.The Exception Shielding pattern is applied to replace the error description text before a response message is returned to the service consumer. Furthermore, the ID value of all database records is appended with a code indicating whether the database record is private or public
• C.Each record in Database A is classified as either private or public. After Service A is invoked by a service consumer (1), it authenticates the request message using an identity store and retrieves the corresponding authorization (2, 3). Once authorized, the service consumer's request is submitted to Database A (4), which then returns the requested data (5) If the service consumer has private access permissions, all of the returned data is included in Service A's response message (6). If the service consumer has public access permissions, then Service A first filters the data in order to remove all unauthorized private data records before sending to the response message to the service consumer (6).
  
  In addition to retrieving data, Service A's data access capability can be used to update database records. An investigation recently revealed an information leakage problem that can occur when service consumers with public access permissions attempt to update the ID value of a database record The ID values of all database records (private or public) must be unique. When a service consumer with public access permissions updates a public database record with an ID value that is already assigned to a private database record, the database returns an error message describing this conflict. This error text reveals confidential information by stating that the ID value submitted by the service consumer with public access permissions already exists within a private database record.
  What steps can be taken to avoid this problem while preserving the requirement that all database records (private and public) have unique ID values?
• D.When Service A detects that a service consumer with public access permissions has submitted an ID value that already exists within a private database record, it stores the service consumer's ID value in a temporary database and returns a response message indicating that the update was successful. A notification message is then sent to a human database administrator who manually contacts the owner of the service consumer in order to explain that the ID value submitted cannot be accepted because it already exists within a private database record.
• E.The service consumer's request message containing the ID value can be encrypted by inserting the private key of the service consumer into the data. Because all service consumers have different private keys, this approach will lead to different encrypted values, even if the plain text ID values are the same. As a result, two data items with the same encrypted unique identifier cannot exist.

Services A, B, and C reside in Service Inventory A and Services D, E, and F reside in Service Inventory B.
Service B is an authentication broker that issues WS-Trust based SAML tokens to Services A and C upon receiving security credentials from Services A and
C. Service E is an authentication broker that issues WS-Trust based SAML tokens to Services D and F upon receiving security credentials from Services D and E.
Service B uses the Service Inventory A identify store to validate the security credentials of Services A and C.
Service E uses the Service Inventory B identity store to validate the security credentials of Services D and F.

It is decided to use Service E as the sole authentication broker for all services in Service Inventories A and B.
Service B is kept as a secondary authentication broker for load balancing purposes. Specifically, it is to be used for situations where authentication requests are expected to be extra time consuming in order to limit the performance burden on Service E.
Even though Service B has all the necessary functionality to fulfill this new responsibility, only Service E can issue SAML tokens to other services.
How can these architectures be modified to support these new requirements?

• A.Because both Service B and Service E issue SAML tokens, these tokens are interchangeable. In order for both services to receive the same amount of authentication requests, a shared key needs to be provided to them for signing the SAML tokens. By signing the SAML tokens with the same key, the SAML tokens generated by Service B cannot be distinguished from the SAML tokens generated by Service E.
• B.When time consuming authentication requests are identified, Service E can forward them to Service B.
  Upon performing the authentication, Service B sends its own signed SAML token to Service E.
  Because Service E trusts Service B.
  it can use the Service B- specific SAML token to issue an official SAML token that is then sent to the original service consumer (that requested authentication) and further used by other services.
• C.To provide load balancing, a service agent needs to be implemented to intercept all incoming requests to Service E.
  The service agent uses a random distribution of the authentication requests between Service B and Service E.
  Because the request messages are distributed in a random manner, the load between the two authentication brokers is balanced.
• D.Because the federation requirements ask for SAML tokens generated by Service E, Service B cannot function as an authentication broker. To address the load balancing requirement, a new utility service needs to be introduced to provide functionality that is redundant with Service E.
  This essentially establishes a secondary authentication broker to which Service E can defer time-consuming authentication tasks at runtime.