Linux malware

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The Linux operating system, Unix and other Unix-like computer operating systems are generally regarded as well-protected against computer viruses.[1]

There has not yet been a single widespread Linux malware threat of the type that Microsoft Windows software currently faces; this is commonly attributed to the malware's lack of root access and fast updates to most Linux vulnerabilities.[2] An additional factor is that there is less incentive for a programmer to write malware for Linux due to its relatively low desktop market share (90.66% Windows vs 0.93% Linux).[3]

The number of malicious programs—including viruses, Trojans, and other threats—specifically written for Linux has been on the increase in recent years and more than doubled during 2005 from 422 to 863.[4]

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[edit] Linux vulnerability

Like other 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 cause any serious consequence to the system itself, the malware would have to gain root access to the system.[2]

One of the vulnerabilities of Linux is that many users think it is not vulnerable to viruses. Tom Ferris, a researcher with Mission Viejo, California-based Security Protocols, said in 2006, "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 ..."[4]

Shane Coursen, a senior technical consultant with Kaspersky Lab noted, "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."[4]

The viruses listed below still pose a potential, although minimal, threat to Linux systems. If an infected binary containing one of the viruses were run, the system would be infected. The infection level would depend on which user with what privileges ran the binary. A binary run under the root account would be able to infect the entire system. Privilege escalation vulnerabilities may permit malware running under a limited account to infect the entire system.

The use of software repositories significantly reduces any threat of installation of malware, as the software repositories are checked by maintainers, who try to ensure that their repository is malware-free. Subsequently, to ensure safe distribution of the software, md5 checksums are made available. Careful use of these digital signatures (which reveal possible modifications by e.g. hijacking of communications using a man-in-the-middle attack or via a redirection attack such as arp or DNS poisoning), provides an additional line of defense, which limits the scope of attacks to include only the original authors, package and release maintainers and possibly others with suitable administrative access, depending on how the keys and checksums are handled.

[edit] Cross-platform viruses

A new area of concern identified in 2007 is that of cross-platform viruses, driven by the popularity of cross-platform applications. This was brought to the forefront of malware awareness by the distribution of an Openoffice.org virus called Bad Bunny.

Stuart Smith of Symantec wrote the following:

"What makes this virus worth mentioning is that it illustrates how easily scripting platforms, extensibility, plug-ins, ActiveX, etc, can be abused. All too often, this is forgotten in the pursuit to match features with another vendor... [T]he ability for malware to survive in a cross-platform, cross-application environment has particular relevance as more and more malware is pushed out via Web sites. How long until someone uses something like this to drop a JavaScript infector on a Web server, regardless of platform?"[5]

[edit] Anti-virus applications

There are several anti-virus applications available for Linux computers, including:

SecurityFocus's Scott Granneman stated,

“ ...some Linux machines definitely need anti-virus software. Samba or NFS servers, for instance, may store documents in undocumented, vulnerable Microsoft formats, such as Word and Excel, that contain and propagate viruses. Linux mail servers should run AV software in order to neutralize viruses before they show up in the mailboxes of Outlook and Outlook Express users."[1] ”

Because they are predominately used on mail servers which may send mail to computers running other operating systems, Linux virus scanners generally use definitions for, and scan for, all known viruses for all computer platforms. For example the open source Clam AV claims that it "Detects over 400.000 viruses, worms and trojans, including Microsoft Office macro viruses, mobile malware, and other threats."[9]

[edit] Threats

The following is a partial list of known Linux malware:

[edit] Trojans

  • Kaiten - Linux.Backdoor.Kaiten trojan horse[10]
  • Rexob - Linux.Backdoor.Rexob trojan[11]

[edit] Viruses

  • Alaeda - Virus.Linux.Alaeda[12]
  • Bad Bunny - Perl.Badbunny[5][13]
  • Binom - Linux/Binom[14]
  • Bliss
  • Brundle[15]
  • Bukowski[16]
  • Diesel - Virus.Linux.Diesel.962[17]
  • Kagob a - Virus.Linux.Kagob.a[18]
  • Kagob b - Virus.Linux.Kagob.b[19]
  • MetaPHOR (also known as Simile)[20]
  • Nuxbee - Virus.Linux.Nuxbee.1403[21]
  • OSF.8759
  • Podloso - Linux.Podloso (The iPod virus)[22][23]
  • Rike - Virus.Linux.Rike.1627[24]
  • RST - Virus.Linux.RST.a[25]
  • Satyr - Virus.Linux.Satyr.a[26]
  • Staog
  • Vit - Virus.Linux.Vit.4096[27]
  • Winter - Virus.Linux.Winter.341[28]
  • Winux (also known as Lindose and PEElf[29]
  • ZipWorm - Virus.Linux.ZipWorm[30]

[edit] Worms

[edit] References

  1. ^ a b Granneman, Scott (October 2003). "Linux vs. Windows Viruses". Retrieved on 2008-03-06.
  2. ^ a b Yeargin, Ray (July 2005). "The short life and hard times of a linux virus". Retrieved on 2008-06-24.
  3. ^ Market share of operating systems, Net Applications, retrieved Sept 5 2008
  4. ^ a b c Patrizio, Andy (April 2006). "Linux Malware On The Rise". Retrieved on 2008-03-08.
  5. ^ a b Smith, Stuart (June 2007). "Bad Bunny". Retrieved on 2008-02-20.
  6. ^ "ESET File Security - Antivirus Protection for Linux, BSD, and Solaris". Eset. Retrieved on 2008-10-26.
  7. ^ "ESET Mail Security - Linux, BSD, and Solaris mail server protection". Eset. Retrieved on 2008-10-26.
  8. ^ "ESET NOD32 Antivirus for Linux Gateway® Devices". Eset. Retrieved on 2008-10-26.
  9. ^ ClamAV (September 2008). "Clam AntiVirus 0.94 User Manual". Retrieved on 2008-12-02.
  10. ^ Florio, Elia (February 2006). "Linux.Backdoor.Kaiten". Retrieved on 2008-03-08.
  11. ^ Florio, Elia (December 2007). "Linux.Backdoor.Rexob". Retrieved on 2008-03-08.
  12. ^ Kaspersky Lab (May 2007). "Virus.Linux.Alaeda". Retrieved on 2008-03-08.
  13. ^ Smith, Stuart (May 2007). "Perl.Badbunny". Retrieved on 2008-03-08.
  14. ^ McAfee (December 2004). "Linux/Binom". Retrieved on 2008-03-08.
  15. ^ Rieck, Konrad and Konrad Kretschmer (August 2001). "Brundle Fly 0.0.1 - A Good-Natured Linux ELF Virus". Retrieved on 2008-03-08.
  16. ^ de Almeida Lopes, Anthony (July 2007). "Project Bukowski". Retrieved on 2008-03-08.
  17. ^ Kaspersky Lab (February 2002). "Virus.Linux.Diesel.962". Retrieved on 2008-03-08.
  18. ^ Kaspersky Lab (April 2001). "Virus.Linux.Kagob.a". Retrieved on 2008-03-08.
  19. ^ Kaspersky Lab (undated). "Virus.Linux.Kagob.b". Retrieved on 2008-03-08.
  20. ^ The Mental Driller (February 2002). "Metamorphism in practice or "How I made MetaPHOR and what I've learnt"". Retrieved on 2008-03-08.
  21. ^ Kaspersky Lab (December 2001). "Virus.Linux.Nuxbee.1403". Retrieved on 2008-03-08.
  22. ^ Ferrie, Peter (April 2007). "Linux.Podloso". Retrieved on 2008-03-08.
  23. ^ Ferrie, Peter (April 2007). "The iPod virus". Retrieved on 2008-03-08.
  24. ^ Kaspersky Lab (August 2003). "Virus.Linux.Rike.1627". Retrieved on 2008-03-08.
  25. ^ Kaspersky Lab (January 2002). "Virus.Linux.RST.a". Retrieved on 2008-03-08.
  26. ^ Kaspersky Lab (March 2001). "Virus.Linux.Satyr.a". Retrieved on 2008-03-08.
  27. ^ Kaspersky Lab (March 2000). "Virus.Linux.Vit.4096". Retrieved on 2008-03-08.
  28. ^ Kaspersky Lab (October 2000). "Virus.Linux.Winter.341". Retrieved on 2008-03-08.
  29. ^ Rautiainen, Sami et al (March 2001). "F-Secure Virus Descriptions : Lindose". Retrieved on 2008-03-08.
  30. ^ Kaspersky Lab (January 2001). "Virus.Linux.ZipWorm". Retrieved on 2008-03-08.
  31. ^ Kaspersky Lab (May 2001). "Net-Worm.Linux.Adm". Retrieved on 2008-03-08.
  32. ^ Rautiainen, Sami (April 2001). "F-Secure Virus Descriptions : Adore". Retrieved on 2008-03-08.
  33. ^ Kaspersky Lab (May 2001). "Net-Worm.Linux.Cheese". Retrieved on 2008-03-08.
  34. ^ Rautiainen, Sami (April 2001). "F-Secure Virus Descriptions : Kork". Retrieved on 2008-03-08.
  35. ^ Kaspersky Lab (October 2002). "Net-Worm.Linux.Mighty". Retrieved on 2008-03-08.
  36. ^ Perriot, Frederic (February 2007). "Linux.Millen.Worm". Retrieved on 2008-03-08.
  37. ^ Rautiainen, Sami et al (September 2002). "F-Secure Virus Descriptions : Slapper". Retrieved on 2008-03-08.
  38. ^ Voss, Joel (December 2007). "SSH Bruteforce Virus by AltSci Concepts". Retrieved on 2008-03-13.

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