The results of the previous audit are an important source of information for an IS auditor to consider when performing the risk assessment prior to an audit engagement, as they can provide insights into the current state and performance of the auditee, identify any issues or gaps that need to be followed up or addressed, and highlight any areas that require special attention or focus. The design of controls is an important factor to evaluate during an audit engagement, but it is not the most important thing to consider when performing the risk assessment prior to an audit engagement, as it does not reflect the actual implementation or effectiveness of the controls. Industry standards and best practices are useful benchmarks or guidelines for an IS auditor to compare or measure against during an audit engagement, but they are not the most important thing to consider when performing the risk assessment prior to an audit engagement, as they may not be applicable or relevant to the specific context or objectives of the auditee. The amount of time since the previous audit is a relevant criterion to determine the frequency or timing of an audit engagement, but it is not the most important thing to consider when performing the risk assessment prior to an audit engagement, as it does not indicate the level or nature of risk associated with the auditee.

Section: Protection of Information Assets
Explanation:
Validated electronic signatures are based on qualified certificates that are created by a certification authority (CA), with the technical standards required to ensure the key can neither be forced nor reproduced in a reasonable time. Such certificates are only delivered through a registration authority (RA) after a proof of identity has been passed. Using strong signatures in e- mail traffic, nonrepudiation can be assured and a sender can be tracked. The recipient can configure their e-mail server or client to automatically delete e-mails from specific senders. For confidentiality issues, one must use encryption, not a signature, although both methods can be based on qualified certificates. Without any filters directly applied on mail gateway servers to block traffic without strong signatures, the workload will not increase.
Using filters directly on a gateway server will result in an overhead less than antivirus software imposes.
Digital signatures are only a few bytes in size and will not slash bandwidth. Even if gateway servers were to check CRLs, there is little overhead.

Explanation
The greatest concern for an IS auditor when evaluating an organization's IT strategy and plans is that IT is not engaged in business strategic planning, as this indicates a lack of alignment between IT and business objectives, which could result in inefficient and ineffective use of IT resources and capabilities. The absence of a defined IT security policy, the nondistribution of business strategy meeting minutes, and the inadequate documentation of IT strategic planning are also issues that should be addressed by an IS auditor, but they are not as significant as IT's noninvolvement in business strategic planning. References: CISA Review Manual (Digital Version), Chapter 3, Section 3.1