A single digitally signed instruction was given to a
financial institution to credit a customer's account. The
financial institution received the instruction three times
and credited the account three times. Which of the following
would be the MOST appropriate control against such multiple
credits?
A. Encrypting the hash of the payment instruction with the
public key of the financial institution.
B. Affixing a time stamp to the instruction and using it to
check for duplicate payments.
C. Encrypting the hash of the payment instruction with the
private key of the instructor.
D. Affixing a time stamp to the hash of the instruction
before being digitally signed by the instructor.
Answer / guest
Answer: B
Affixing a time stamp to the instruction and using it to
check for duplicate payments makes the instruction unique.
The financial institution can check that the instruction was
not intercepted and replayed and thus it could prevent
crediting the account three times. Encrypting the hash of
the payment instruction with the public key of the financial
institution does not protect replay, it only protects
confidentiality and integrity of the instruction. Encrypting
the hash of the payment instruction with the private key of
the instructor ensures integrity of the instruction and
nonrepudiation of the issued instruction. The process of
creating a message digest requires applying a cryptographic
hashing algorithm to the entire message. The receiver, upon
decrypting the message digest, will re-compute the hash
using the same hashing algorithm and compare the result with
what was sent. Hence, affixing a time stamp into the hash of
the instruction before being digitally signed by the
instructor would violate the integrity requirements of
digital signature.
| Is This Answer Correct ? | 2 Yes | 0 No |
Which tests is an IS auditor performing when certain program is selected to determine if the source and object versions are the same?
IS auditors are MOST likely to perform compliance tests of internal controls if, after their initial evaluation of the controls, they conclude that: A. a substantive test would be too costly. B. the control environment is poor. C. inherent risk is low. D. control risks are within the acceptable limits.
Which of the following types of firewalls would BEST protect a network from an Internet attack? A. Screened subnet firewall B. Application filtering gateway C. Packet filtering router D. Circuit-level gateway
A network diagnostic tool that monitors and records network information is a/an: A. online monitor. B. downtime report. C. help desk report. D. protocol analyzer.
In the course of performing a risk analysis, an IS auditor has identified threats and potential impacts. Next, an IS auditor should: A. identify and assess the risk assessment process used by management. B. identify information assets and the underlying systems. C. disclose the threats and impacts to management. D. identify and evaluate the existing controls.
Which of the following is the PRIMARY safeguard for securing software and data within an information processing facility? A. Security awareness B. Reading the security policy C. Security committee D. Logical access controls
A web-based bookstore has included the customer relationship management (CRM) system in its operations. An IS auditor has been assigned to perform a call center review. Which of the following is the MOST appropriate first step for the IS auditor to take? A. Review the company's performance since the CRM was implemented. B. Review the IT strategy. C. Understand the business focus of the bookstore. D. Interview salespeople and supervisors.
The knowledge base of an expert system that uses questionnaires to lead the user through a series of choices before a conclusion is reached is known as: A. rules. B. decision trees. C. semantic nets. D. data flow diagrams.
Which of the following provisions in a contract for external information systems services would an IS auditor consider to be LEAST significant? A. Ownership of program and files B. Statement of due care and confidentiality C. Continued service of outsourcer in the event of a disaster D. Detailed description of computer hardware used by the vendor
Which of the following would enable an enterprise to provide access to its intranet (i.e., extranet) across the Internet to its business partners? A. Virtual private network B. Client-server C. Dial-in access D. Network service provider
Which of the following security techniques is the BEST method for authenticating a user's identity? A. Smart card B. Biometrics C. Challenge-response token D. User ID and password
Responsibility and reporting lines cannot always be established when auditing automated systems since: A. diversified control makes ownership irrelevant. B. staff traditionally change jobs with greater frequency. C. ownership is difficult to establish where resources are shared. D. duties change frequently in the rapid development of technology.