Security Problems with Multiprogramming and Time-Sharing Environment

In a multiprogramming and time-sharing environment, several users share the system simultaneously. This situation can result in various security problems. 

These are the following:

      To lower the cost of of providing computing capability, time-sharing and multiprogramming made it possible for individuals and organizations to use ocmputer without owning one (such as in Internet Cafes, laborities in school, etc.). It also promotes the interactive sense of using computers.

 (1.)

      Let us state some computer laboratories in schools as an instance. Because users share the system simultaneously, they have the opportunity to copy other user's file from the system. Once a user saves a file to his/her unit, other users of that group or connected system may also have an access to the file. Other users may change an information inside the file or even steal the file from the owner itself without the owner knowing it. They may also modify the files or programs that was saved or ran by the owner. Furthermore, some of the threats that the owner of a certain file may encounter is the data confidentiality. Without him not being aware of the system used as the time-sharing and multiprogramming, he may insert or have a secret or confidential data that he wants to remain at the file. Another one is the data integrity. Other users may change, add, or even remove some information in the file if he wants to.

(2.)

      Internet cafes also have a multiprogramming and time-sharing environment. Some internet cafes have hardwares like printers that is also connected with the system. State that a certain user is asking the attendant to print a certain file form his unit. The file now is being printed. There comes this another user that accidentally hit the print button and clicked OK, so the file is being processed to be printed. The result is, it will interrupt the current printing process . It will cause the printer to mix output in printing the data because the other user is now accidentally printing his own file. Because they also share system resources, it will interrupt other current processing files.

Can we ensure the same degree of security in a time-share machine as we have in a dedicated machine?

      A time-share machine is interactive and is used by many users and performs different functions or tasks while a dedicated machine's purpose is to serve one primary function or task. We can not ensure the same degree of security because they are used in different ways and since human's security protection can be also hacked, broked, or damaged by others, it will be more difficult to for users to know the right usage and controls of the machines. For example, an automobile which is a dedicated machine will have its own level of security because it's usage is dedicated solely to the navigation of the car which is not the same with the time-shared machines which can be accessed by others if and only if the authority or the main system implements a certain security for the protection of the files.