• Establish entry-wide procedures for making changes to production programs.
• Establish an educational program to raise user awareness regarding threats from viruses and malicious programs.
• Install all new applications on a stand-alone computer and thoroughly test them with antiviral software prior to implementing then on the mainframe or local area network (LAN) server.
• Routinely make backup copies of key files stored on mainframe, server, and workstations.
• Wherever possible, limit users to read and execute rights only. This allows users to extract data and run authorized applications, but denies them the ability to write directly to mainframe and sever directories.
• Require protocols that explicitly invoke the operating system’s log-on procedures to bypass Trojan horses. A typical scenario is one in which a user sits down to a terminal that is already displaying the log-on screen and procedure to enter his or her ID and password. This, however, may be a Trojan horse rather than the legitimate procedure. Some operating systems allow the user to directly invoke the operating system log-on procedure by entering a key sequence such as CTRL + ALT + DEL. The user then knows that the log-on procedure on the screen is legitimate.
• Use antiviral software (also called vaccines) to examine application and operating system programs for the presence of a virus and remove it from the affected program. Antiviral programs are used to safeguard mainframes, network servers, and personal computer and automatically test all files that are uploaded to the host. The software, however, works only on known viruses. If a virus has been modified slightly (mutated), there is no guarantee that the vaccine will work. Therefore, maintaining a current version of the vaccine is critical.
Audit Objective Relating to Viruses
And Other Destructive Programs
The key to computer virus control is prevention through strict adherence to organizational policies and procedures that guard against virus infection. The auditor’s objective is to verify that effective management policies and procedures are in place to prevent the introduction and spread of destructive programs, including viruses, worms, back doors, logic bombs, and Trojan horses.