Linux malware includes viruses, Trojans, worms and other types of malware that affect the Linux family of operating systems. Linux, Unix and other Unix-like computer operating systems are generally regarded as very well-protected against, but not immune to, computer viruses.
Like Unix systems, Linux implements a multi-user environment where users are granted specific privileges and there is some form of access control implemented. To gain control over a Linux system or to cause any serious consequences to the system itself, the malware would have to gain root access to the system.
In the past, it has been suggested that Linux had so little malware because its low market share made it a less profitable target. Rick Moen, an experienced Linux system administrator, counters that:
[That argument] ignores Unix's dominance in a number of non-desktop specialties, including Web servers and scientific workstations. A virus/trojan/worm author who successfully targeted specifically Apache httpd Linux/x86 Web servers would both have an extremely target-rich environment and instantly earn lasting fame, and yet it doesn't happen.
In 2008 the quantity of malware targeting Linux was noted as increasing. Shane Coursen, a senior technical consultant with Kaspersky Lab, said at the time, "The growth in Linux malware is simply due to its increasing popularity, particularly as a desktop operating system ... The use of an operating system is directly correlated to the interest by the malware writers to develop malware for that OS."
Tom Ferris, a researcher with Security Protocols, commented on one of Kaspersky's reports, stating, "In people's minds, if it's non-Windows, it's secure, and that's not the case. They think nobody writes malware for Linux or Mac OS X. But that's not necessarily true."
Some Linux users do run Linux-based anti-virus software to scan insecure documents and email which comes from or is going to Windows users. SecurityFocus's Scott Granneman stated:
some Linux machines definitely need anti-virus software.