Prof. Ekta Parikh DDU SEM 3 System Analysis and Design
Chapter 8
Control, audit and security of
Information system
CONTROLS
It is very important to ensure the reliability of reports produced by an information system If
unreliability is seen by users the entire credibility of the system is lost Ensuring reliability is not difficult
for small systems but when a system has to handle massive data it is a challenge Systematic controls
are thus essential when a system is designed.
AUDITS
Many organizations are now entirely dependent on computer based information system. These
information systems contain financial data and other critical procedures. It is essential to protect the
systems against frauds and ensure that sound accounting practices are followed. It is necessary to trace
the origin and fix responsibilities when frauds occur. Audit methods primary purpose is to ensure this.
TESTING
Systems contain many individual subsystems. Usually sub-systems and programs are individually tested
However when a whole system is integrated unforeseen errors may be seen. Thus before releasing a
system the entire operational system should be tested for correctness and completeness.
SECURITY
Systems contain sensitive data about the organization and also about persons working in the
organization. Sensitive data should be protected from spies, thieves or disgruntled employees. Thus
access should be carefully controlled and provided only on a need to know basis. When computers are
networked corruption/erasure may take place due to viruses. Services may be disrupted due to denial of
service attacks thus systems should be designed with appropriate security measures.
CONTROL- Method to ensure that a system processes data as per design and that all data is
included and are correct
AUDIT AND TESTING - Ensure that the system is built as per specifications and that processed
results are correct. Protect systems from frauds.
