F-Secure plc (formerly Data Fellows) is an anti-virus and computer security software company based in Helsinki, Finland. The company has large branch offices in the USA and Japan, where some antivirus analysis and software development work is also being undertaken. F-Secure Corp. is publicly traded on the Helsinki Stock Exchange under the symbol FSC.

Mikko Hyppönen is the Chief Research Officer.

The company sells security software to fight malicious code on diverse platforms:

* F-Secure's IBM PC compatible offerings traditionally had an emphasis on protecting the Microsoft Windows platform, but Linux versions of comparable functionality have been introduced during 2004 and 2005.
o F-Secure 2008: Home user and SOHO oriented protection for Windows desktops and laptops, central management is done by the vendor. Rebadged versions are also available via many ISPs selling monthly or yearly subscription plans. Includes child-lock and web-censorship filtering functionality for parents.
o F-Secure Protection Service: Integrated protection suite for smaller companies, with defensive feature set and hosted web-based central management
o F-Secure Anti-Virus: Traditional antivirus defence for corporate Windows workstations and servers, with Java-based unified central management
o F-Secure Client Security: Integrated protection suite for corporate Windows workstations. Uses antivirus, behavioural analysis, sandboxing, anti-rootkit and personal firewall technologies for security, with Java-based central management
o F-Secure Linux Security: Integrated protection for corporate Linux servers and workstations, available RPM and DEB packages support up to 28 popular Linux distributions, with Java-based central management
o F-Secure for Exchange: Anti-virus and anti-spam defence for corporate Exchange mail server and cluster installations, with Java-based central management
o F-Secure Policy Manager Framework: A combination of Sun Java based platform independent GUI and a customized Apache webserver to centrally manage up to 15,000 seats of F-Secure corporate installations
o F-Secure Messaging Security Gateway: A family of re-badged Proofpoint intelligent spam-filtering appliances, which run an extra layer of F-Secure anti-virus protection on custom Linux-based rack-mount server hardware. Management via local rich web interface.

* F-Secure also produces products to counter mobile malware threats. Security software for the Windows CE derived handhelds and Symbian smartphones are available. The company's public weblog closely follows the mobile malware situation and has been voted as one of the web's 500 most read blog sources. The company also claims to be the first antivirus vendor to establish a World Wide Web presence back in 1994.

F-Secure products for the PC traditionally feature CounterSign, an anti-virus technology integrating multiple scanning engines for on-access malware and adware identification as well as run-time detection of root kits. F-Secure has OEM agreements with several security vendors to integrate detection technology engines in its own offerings, including a long-standing cooperation with Kaspersky Lab, Russia, Frisk of Iceland and sandbox specialist Norman AB. Its products previously included Kaspersky, Orion, Pegasus, Draco, Libra, Hydra and Gemini with Blacklight and DeepGuard (F-Secure's own products). However, the newest version includes only Kaspersky extended base engine, Hydra, Gemini, Pegasus, the new DeepGuard 2.0 and Blacklight, in order to be lighter on system resources. This choice also resulted in an improved detection rate

DeepGuard, now in its 2.0 incarnation, is an F-Secure in-house developed HIPS or advanced system monitoring technology, which detects new or unknown malware intrusions based on unusual, suspicious changes in the Windows system and automatically blocks processes caught in the act. The solution featured well in c't magazine's 2008 January comparative test, where it uniquely stopped all 12 tested threats without the use of traditional anti-virus signatures. DeepGuard, however is resource intensive and requires fairly strong hardware to work without affecting customer experience (1GHz+ CPU and 512MB RAM or better recommended).
Engines used by F-Secure Client Security 8

F-Secure's patented workstation side e-mail and web traffic filtering method is an unusual solution, which relies on a wedge-and-pump software module to syphon off traffic from the NDIS layer, before inspecting and re-inserting the content. This venue is theoretically safer than the "local proxy" based solution used by most competitors, but the strictly on-line nature of checks causes time-out issues with large, complex files and attachments on lower-end hardware based systems.