Try and practice the latest SOA : S90.20 real questions & answers

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.

The service contracts of Services A and B both comply with the same XML schema.
However, each organization employs different security technologies for their service architectures. To protect the confidential financial data sent by Service A to Service B, each organization decides to independently apply the Data Confidentiality and the Data Origin Authentication patterns to establish message-layer security for external message exchanges. However, when an encrypted and digitally signed test message is sent by Service A to Service B, Service B was unable to decrypt the message.
Which of the following statements describes a solution that solves this problem?

• A. The problem with the test message occurred because Service A used incorrect keys to protect the message sent to Service B.
  Service A used its own public key to sign the message and then used Service B's public key to encrypt the message content. To correct the problem, Service A must use WS-SecureConversation to agree on a secret session key to be used to encrypt messages exchanged between Services A and B.
  Because this session key is only known by Services A and B, encrypting the messages with this key also provides authentication of the origin of the data.
• B. Although both of the organizations successfully applied the Data Confidentiality and the Data Origin Authentication patterns, the order in which the patterns were applied is incorrect. The application of the Data Origin Authentication pattern must always follow the application of the Data Confidentiality pattern to ensure that the message confidentiality from a third party authenticates the origin of the message.
• C. The problem with the test message occurred because Service A needed the private key of Service B to digitally sign the message. An attacker pretending to be Service B likely sent a fake private/public keys pair to Service A.
  Using these fake keys to encrypt and digitally sign the message made the message incompatible for Service B.
  Because the fake private key was also used to sign the hash, it explains the source of the problem.
• D. Although both of the organizations applied the Data Confidentiality and the Data Origin Authentication patterns, the security technologies used for the Service A and Service B architectures may be incompatible. Because there are several technologies and versions of technologies that can be used to apply these patterns, the organizations need to standardize implementation level details of the relevant security technologies.

Service Consumer A sends a request message to Service A (1), after which Service A sends a request message to Service B (2). Service B forwards the message to have its contents calculated by Service C (3). After receiving the results of the calculations via a response message from Service C (4), Service B then requests additional data by sending a request message to Service D (5). Service D retrieves the necessary data from Database A (6), formats it into an XML document, and sends the response message containing the XML-formatted data to Service B (7).
Service B appends this XML document with the calculation results received from Service C, and then records the entire contents of the XML document into Database B (8). Finally, Service B sends a response message to Service A (9) and Service A sends a response message to Service Consumer A (10).

Services A, B and D are agnostic services that belong to Organization A and are also being reused in other service compositions. Service C is a publicly accessible calculation service that resides outside of the organizational boundary. Database A is a shared database used by other systems within Organization A and Database B is dedicated to exclusive access by Service B.
Service B has recently been experiencing a large increase in the volume of incoming request messages. It has been determined that most of these request messages were auto-generated and not legitimate. As a result, there is a strong suspicion that the request messages originated from an attacker attempting to carry out denial-of-service attacks on Service B.
Additionally, several of the response messages that have been sent to Service A from Service B contained URI references to external XML schemas that would need to be downloaded in order to parse the message data. It has been confirmed that these external URI references originated with data sent to Service B by Service C.
The XML parser currently being used by Service A is configured to download any required XML schemas by default. This configuration cannot be changed.
What steps can be taken to improve the service composition architecture in order to avoid future denial-of-service attacks against Service B and to further protect Service A from data access-oriented attacks?

• A. Apply the Service Perimeter Guard pattern and the Message Screening pattern together to establish a service perimeter guard that can filter response messages from Service C before they reach Services A and B.
  The filtering rules are based on the IP address of Service C.
  If a request message originates from an IP address not listed as one of the IP addresses associated with Service C.
  then the response message is rejected.
• B. Apply the Direct Authentication pattern so that Service C is required to provide security credentials, such as Username tokens, with any response messages it sends to Service B.
  Furthermore, add logic to Service A so that it can validate security credentials passed to it via response messages from Service B.
  by using an identity store that is shared by Services A and B.
• C. Apply the Data Origin Authentication pattern so that Service B can verify that request messages that claim to have been sent by Service A actually did originate from Service A.
  Apply the Message Screening pattern to add logic to Service A so that it can verify that external URIs in response messages from Service B refer to trusted sources.
• D. Apply the Service Perimeter Guard pattern to establish a perimeter service between Service B and Service C.
  Apply the Brokered Authentication pattern by turning the perimeter service into an authentication broker that is capable of ensuring that only legitimate response messages are being sent to Service C from Service B Further apply the Data Origin Authentication pattern to enable the perimeter service to verify that messages that claim to have been sent by Service C actually originated from Service C.
  Apply the Message Screening pattern to add logic to the perimeter service to also verify that URIs in request messages are validated against a list of permitted URIs from where XML schema downloads have been pre-approved.

Service Consumer A sends a request message to Service A (1), after which Service A sends a request message with security credentials to Service B (2). Service B authenticates the request and, if the authentication is successful, writes data from the request message into Database B (3). Service B then sends a request message to Service C (4), which is not required to issue a response message. Service B then sends a response message back to Service A (5). After processing Service B's response, Service A sends another request message with security credentials to Service B (6). After successfully authenticating this second request message from Service A, Service B sends a request message to Service D (7). Service D is also not required to issue a response message. Finally, Service B sends a response message to Service A (8), after which Service A records the response message contents in Database A (9) before sending its own response message to Service Consumer A (10).

To use Service A, Service Consumer A is charged a per usage fee. The owner of Service Consumer A has filed a complaint with the owner of Service A, stating that the bills that have been issued are for more usage of Service A than Service Consumer A actually used.
Additionally, it has been discovered that malicious intermediaries are intercepting and modifying messages being sent from Service B to Services C and D.
Because Services C and D do not issue response messages, the resulting errors and problems were not reported back to Service B.
Which of the following statements describes a solution that correctly addresses these problems?

• A. Apply the Brokered Authentication to establish an authentication broker between Service Consumer A and Service A that can carry out the Kerberos authentication protocol. Before invoking Service A, Service Consumer A must request a ticket granting ticket and then it must request service granting tickets to all services in the service composition, including Services C and D.
  Messages sent by Service B to Services C and D must further be encrypted with the public key of Service Consumer A.
• B. Apply the Service Perimeter Guard and the Message Screening patterns together to establish a perimeter service between Service Consumer A and Service A.
  The perimeter service screens and authenticates incoming request messages from Service Consumer A.
  After successful authentication, the perimeter service generates a signed SAML assertion that is used by the subsequent services to authenticate and authorize the request message and is also carried forward as the security credential included in messages sent to Services C and D.
• C. The Data Confidentiality and Data Origin Authentication patterns need to be applied in order to establish message-layer confidentiality and integrity for messages sent to Services C and D.
  The Direct Authentication pattern can be applied to require that service consumer be authenticated in order to use Service A.
• D. Messages sent to Services C and D must be protected using transport-layer encryption in order to ensure data confidentiality. Service consumers of Service A must be authenticated using X.509 certificates because they can be reused for several request messages.