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Operating System (O/S)

The main program responsible for organizing and directing the resources of a computer - both hardware and software - so that a user can effectively use it to perform various tasks.

There are a handful of operating systems (sometimes abbreviated as 'os' or 'o/s') available for the general user, each offering unique advantages and disadvantages.

How An Operating System Works

A simple way to understand an OS is to think of it as a facilitator - its job is to make sure that whatever the user wants to happen, does so, and does so seamlessly and efficiently. Like an air traffic controller at a busy airport, the OS directs the vital activity that underpins the airport - but the passenger, or user, only needs to worry about what they want to do.

An OS is involved in a wide variety of tasks, such as:

  • Managing a computer's physical resources (CPU, RAM, etc) so that they process data efficiently;
  • Organize data on the computer's hard disk;
  • Managing data processes and programs efficiently so that they do not overwhelm the capabilities of the available hardware;
  • 'Interpreting' the interactions between the user and the computer - for example, translating movements of the physical mouse to actions affecting programs;

Early on in computing history, many of these tasks needed to be done by the human users. As operating systems have progressed however, these tasks have become automated, and using computers has become steadily less technically-demanding and more accessible to the general population.

Operating Systems and Malware

Understandably, since operating systems are so vital to computer use, they are the main target of most types of attacks. An attack on an OS will typically subvert a legitimate operating process - such as opening a file or running a program - and 'hijack' it for the attacker's own purposes. Types of malware that do so include viruses, worms, rootkits, backdoors and so on.



On-Access Scanner

A virus scanner that runs as a real-time, background process while the user performs other tasks, in order to provide constant protection against malware. This is in contrast to On-DemandScanners, which a user must manually launch.



On-Demand Scanner

A specialized program that scans files on the computer system for infection.

'On-demand' indicates the user must manually launch the scanner before it will check the system for infection; this is in contrast to On-Access Scanners, which is a more constant process that quietly checks files in the background while the user continues with their tasks in the foreground.

Virus scanners are typically a major component of comprehensive antivirus programs, but standalone virus scanner of varying quality can also be found freely available online.




OSX is the platform designator for Apple's Mac OS X and is simply shorthand for 'Operating system version 10'.

Mac OS X is based on Unix-like architecture and is the successor to the Classic MacOS series.




The Type designation 'Joke' was previously used by F-Secure to describe a program that does not easily fit into any other Type categorization.

With changes in the threat landscape today, programs previously identified as 'Other' have been reclassified under the Riskware Category, with the Type designation 'Application'.

The update in naming better clarifies the program's overall security profile in the current, more complex threat landscape.





A classification term used by F-Secure to indicate the potential severity of threat a program may pose to the user's computer system and/or confidential information.



About Detection Names

A quick guide to Detections - why they are important, how they work and how to read them. Also includes Generic Detections and how they differ from traditional Detections.