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Antivirus software

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Antivirus or anti-virus software is used to prevent, detect, and sex malware, including but not limited to computer viruses, computer worms, trojan horses, spyware and adware. Computer security, including protection from social engineering techniques, is commonly offered in products and services of antivirus software companies. This page discusses the software used for the prevention and removal of malware threats, rather than computer security implemented by software methods.

A variety of strategies are typically employed. Signature-based detection involves searching for known patterns of data within executable code. However, it is possible for a computer to be infected with new malware for which no signature is yet known. To counter such so-called zero-day threats, heuristics can be used. One type of heuristic approach, generic signatures, can identify new viruses or variants of existing viruses by looking for known malicious code, or slight variations of such code, in files. Some antivirus software can also predict what a file will do by running it in a sandbox and analyzing what it does to see if it performs any malicious actions.

No matter how useful antivirus software can be, it can sometimes have drawbacks. Antivirus software can impair a computer's performance. Inexperienced users may also have trouble understanding the prompts and decisions that antivirus software presents them with. An incorrect decision may lead to a security breach. If the antivirus software employs heuristic detection, success depends on achieving the right balance between false positives and false negatives. False positives can be as destructive as false negatives.[1] Finally, antivirus software generally runs at the highly trusted kernel level of the operating system, creating a potential avenue of attack.[2]

History

An example of free antivirus software: ClamTk 3.08.
See also: Timeline of notable computer viruses and worms

Most of the computer viruses written in the early and mid 1980s were limited to self-reproduction and had no specific damage routine built into the code.[3] That changed when more and more programmers became acquainted with virus programming and created viruses that manipulated or even destroyed data on infected computers.

There are competing claims for the innovator of the first antivirus product. Possibly the first publicly documented removal of a computer virus in the wild was performed by Bernd Fix in 1987.[4][5] There were also two antivirus applications for the Atari ST platform developed in 1987. The first one was G Data [6] and second was UVK 2000.[7]

Fred Cohen, who published one of the first academic papers on computer viruses in 1984,[8] began to develop strategies for antivirus software in 1988[9] that were picked up and continued by later antivirus software developers. In 1987, he published a demonstration that there is no algorithm that can perfectly detect all possible viruses.[10]

Also in 1988 a mailing list named VIRUS-L[11] was started on the BITNET/EARN network where new viruses and the possibilities of detecting and eliminating viruses were discussed. Some members of this mailing list like John McAfee or Eugene Kaspersky later founded software companies that developed and sold commercial antivirus software.

Before internet connectivity was widespread, viruses were typically spread by infected floppy disks. Antivirus software came into use, but was updated relatively infrequently. During this time, virus checkers essentially had to check executable files and the boot sectors of floppy disks and hard disks. However, as internet usage became common, viruses began to spread online.[12]

Over the years it has become necessary for antivirus software to check an increasing variety of files, rather than just executables, for several reasons:

  • Powerful macros used in word processor applications, such as Microsoft Word, presented a risk. Virus writers could use the macros to write viruses embedded within documents. This meant that computers could now also be at risk from infection by opening documents with hidden attached macros.[13]
  • The possibility of embedding executable objects inside otherwise non-executable file formats can make opening those files a risk.[14]
  • Later email programs, in particular Microsoft's Outlook Express and Outlook, were vulnerable to viruses embedded in the email body itself. A user's computer could be infected by just opening or previewing a message.[15]

As always-on broadband connections became the norm, and more and more viruses were released, it became essential to update virus checkers more and more frequently. Even then, a new zero-day virus could become widespread before antivirus companies released an update to protect against it.

Identification methods

File:MalwarebytesMainGUI.png
Malwarebytes' Anti-Malware version 1.46 - a proprietary freeware antimalware product

One of the few solid theoretical results in the study of computer viruses is Frederick B. Cohen's 1987 demonstration that there is no algorithm that can perfectly detect all possible viruses.[10] The proof relies on the "infect" and "spread" abilities of computer viruses. While common, the "infect" and "spread" abilities of a computer code, which create the "replicate" ability, are not necessarily contained in malware. "Computer virus", in its recent meaning, and "malware" are overlapping terms, but not synonymous. The difference is between a code with the ability to "infect" and "spread" and a code with malicious purpose.[citation needed]

There are several methods which antivirus software can use to identify malware.

Signature based detection is the most common method. To identify viruses and other malware, antivirus software compares the contents of a file to a dictionary of virus signatures. Because viruses can embed themselves in existing files, the entire file is searched, not just as a whole, but also in pieces.[16]

Heuristic-based detection, like malicious activity detection, can be used to identify unknown viruses.

File emulation is another heuristic approach. File emulation involves executing a program in a virtual environment and logging what actions the program performs. Depending on the actions logged, the antivirus software can determine if the program is malicious or not and then carry out the appropriate disinfection actions.[17]

Signature-based detection

Traditionally, antivirus software heavily relied upon signatures to identify malware. This can be very effective, but cannot defend against malware unless samples have already been obtained and signatures created. Because of this, signature-based approaches are not effective against new, unknown viruses.

As new viruses are being created each day, the signature-based detection approach requires frequent updates of the virus signature dictionary. To assist the antivirus software companies, the software may allow the user to upload new viruses or variants to the company, allowing the virus to be analyzed and the signature added to the dictionary.[16] Signatures are obtained by human experts using reverse engineering.[citation needed] An example of software used in reversed engineering is Interactive Disassembler. Such a software does not implement antivirus protection, but facilitates human analysis.[citation needed]

Although the signature-based approach can effectively contain virus outbreaks, virus authors have tried to stay a step ahead of such software by writing "oligomorphic", "polymorphic" and, more recently, "metamorphic" viruses, which encrypt parts of themselves or otherwise modify themselves as a method of disguise, so as to not match virus signatures in the dictionary.[18]

Heuristics

Some more sophisticated antivirus software uses heuristic analysis to identify new malware or variants of known malware.

Many viruses start as a single infection and through either mutation or refinements by other attackers, can grow into dozens of slightly different strains, called variants. Generic detection refers to the detection and removal of multiple threats using a single virus definition.[19]

For example, the Vundo trojan has several family members, depending on the antivirus vendor's classification. Symantec classifies members of the Vundo family into two distinct categories, Trojan.Vundo and Trojan.Vundo.B.[20][21]

While it may be advantageous to identify a specific virus, it can be quicker to detect a virus family through a generic signature or through an inexact match to an existing signature. Virus researchers find common areas that all viruses in a family share uniquely and can thus create a single generic signature. These signatures often contain non-contiguous code, using wildcard characters where differences lie. These wildcards allow the scanner to detect viruses even if they are padded with extra, meaningless code.[22] A detection that uses this method is said to be "heuristic detection."

Variants of viruses are referred to with terminology such as: "oligomorphic", "polymorphic" and "metamorphic", where the differences between specific variants of the same virus are significantly high.[citation needed] In such cases, there are dedicated statistical analysis-based algorithms, implemented in the "real time" protection, which analyses software behaviour. This approach is not absolutely exact and results in higher resource usage on the computer. Since "oligomorphic", "polymorphic" and "metamorphic" engine development is difficult and the resulting computer code has a (relatively) high dimension (although such cases are very rare), this approach can be used with a relatively high success rate.[citation needed] This approach may imply human ingeniousness for the design of the algorithm.[citation needed]

If the antivirus software employs heuristic detection, success depends on achieving the right balance between false positives and false negatives. Due to the existence of the possibility of false positives and false negatives, the identification process is subject to human assistance which may include user decisions, but also analysis from an expert of the antivirus software company.[citation needed]

Rootkit detection

Main article: Rootkit

Anti-virus software can attempt to scan for rootkits; a rootkit is a type of malware that is designed to gain administrative-level control over a computer system without being detected. Rootkits can change how the operating system functions and in some cases can tamper with the anti-virus program and render it ineffective. Rootkits are also difficult to remove, in some cases requiring a complete re-installation of the operating system. [23]

Issues of concern

Unexpected renewal costs

Some commercial antivirus software end-user license agreements include a clause that the subscription will be automatically renewed, and the purchaser's credit card automatically billed, at the renewal time without explicit approval. For example, McAfee requires users to unsubscribe at least 60 days before the expiration of the present subscription[24] while BitDefender sends notifications to unsubscribe 30 days before the renewal.[25] Norton AntiVirus also renews subscriptions automatically by default.[26]

Rogue security applications

Main article: Rogue security software

Some apparent antivirus programs are actually malware masquerading as legitimate software, such as WinFixer, MS Antivirus, and Mac Defender.[27]

Problems caused by false positives

A "false positive" is when antivirus software identifies a non-malicious file as a virus. When this happens, it can cause serious problems. For example, if an antivirus program is configured to immediately delete or quarantine infected files, a false positive in an essential file can render the operating system or some applications unusable.[28] In May 2007, a faulty virus signature issued by Symantec mistakenly removed essential operating system files, leaving thousands of PCs unable to boot.[29] Also in May 2007, the executable file required by Pegasus Mail was falsely detected by Norton AntiVirus as being a Trojan and it was automatically removed, preventing Pegasus Mail from running. Norton AntiVirus had falsely identified three releases of Pegasus Mail as malware, and would delete the Pegasus Mail installer file when that happened.[30] In response to this Pegasus Mail stated:

On the basis that Norton/Symantec has done this for every one of the last three releases of Pegasus Mail, we can only condemn this product as too flawed to use, and recommend in the strongest terms that our users cease using it in favour of alternative, less buggy anti-virus packages.[30]

In April 2010, McAfee VirusScan detected svchost.exe, a normal Windows binary, as a virus on machines running Windows XP with Service Pack 3, causing a reboot loop and loss of all network access.[31][32]

In December 2010, a faulty update on the AVG anti-virus suite damaged 64-bit versions of Windows 7, rendering it unable to boot, due to an endless boot loop created.[33]

In October 2011, Microsoft Security Essentials (MSE) removed the Google Chrome web browser, rival to Microsoft's own Internet Explorer. MSE flagged Chrome as a Zbot banking trojan.[34]

When Microsoft Windows becomes damaged by faulty anti-virus products, fixing the damage to Microsoft Windows incurs technical support costs and businesses can be forced to close whilst remedial action is undertaken.[35][36]

Running multiple antivirus programs concurrently can degrade performance and create conflicts.[37] However, using a concept called multiscanning, several companies (including G Data[38] and Microsoft[39]) have created applications which can run multiple engines concurrently.

It is sometimes necessary to temporarily disable virus protection when installing major updates such as Windows Service Packs or updating graphics card drivers.[40] Active antivirus protection may partially or completely prevent the installation of a major update. Anti-virus software can cause problems during the installation of an operating system upgrade, e.g. when upgrading to a newer version of Windows "in place" — without erasing the previous version of Windows. Microsoft recommends that anti-virus software be disabled to avoid conflicts with the upgrade installation process.[41][42][43]

The functionality of a few software programs can be hampered by active anti-virus software. For example TrueCrypt, a disk encryption program, states on its troubleshooting page that anti-virus programs can conflict with TrueCrypt and cause it to malfunction or operate very slowly.[44]

Support issues also exist around antivirus application interoperability with common solutions like SSL VPN remote access and network access control products.[45] These technology solutions often have policy assessment applications which require that an up to date antivirus is installed and running. If the antivirus application is not recognized by the policy assessment, whether because the antivirus application has been updated or because it is not part of the policy assessment library, the user will be unable to connect.

Effectiveness

Studies in December 2007 showed that the effectiveness of antivirus software had decreased in the previous year, particularly against unknown or zero day attacks. The computer magazine c't found that detection rates for these threats had dropped from 40-50% in 2006 to 20-30% in 2007. At that time, the only exception was the NOD32 antivirus, which managed a detection rate of 68 percent.[46]

The problem is magnified by the changing intent of virus authors. Some years ago it was obvious when a virus infection was present. The viruses of the day, written by amateurs, exhibited destructive behavior or pop-ups. Modern viruses are often written by professionals, financed by criminal organizations.[47]

Independent testing on all the major virus scanners consistently shows that none provide 100% virus detection. The best ones provided as high as 99.6% detection, while the lowest provided only 81.8% in tests conducted in February 2010. All virus scanners produce false positive results as well, identifying benign files as malware.[48]

Although methodologies may differ, some notable independent quality testing agencies include AV-Comparatives, ICSA Labs, West Coast Labs, VB100 and other members of the Anti-Malware Testing Standards Organization.[49]

New viruses

Anti-virus programs are not always effective against new viruses, even those that use non-signature-based methods that should detect new viruses. The reason for this is that the virus designers test their new viruses on the major anti-virus applications to make sure that they are not detected before releasing them into the wild.[50]

Some new viruses, particularly ransomware, use polymorphic code to avoid detection by virus scanners. Jerome Segura, a security analyst with ParetoLogic, explained:[51]

It's something that they miss a lot of the time because this type of [ransomware virus] comes from sites that use a polymorphism, which means they basically randomize the file they send you and it gets by well-known antivirus products very easily. I've seen people firsthand getting infected, having all the pop-ups and yet they have antivirus software running and it's not detecting anything. It actually can be pretty hard to get rid of, as well, and you're never really sure if it's really gone. When we see something like that usually we advise to reinstall the operating system or reinstall backups.[51]

A proof of concept virus has used the Graphics Processing Unit (GPU) to avoid detection from anti-virus software. The potential success of this involves bypassing the CPU in order to make it much harder for security researchers to analyse the inner workings of such malware.[52]

Rootkits

Detecting rootkits is a major challenge for anti-virus programs. Rootkits have full administrative access to the computer and are invisible to users and hidden from the list of running processes in the task manager. Rootkits can modify the inner workings of the operating system[53] and tamper with antivirus programs.

Damaged files

Files which have been damaged by computer viruses are normally damaged beyond recovery. Anti-virus software removes the virus code from the file during disinfection, but this does not always restore the file to its undamaged state. In such circumstances, damaged files can only be restored from existing backups; installed software that is damaged requires re-installation.[54]

Firmware issues

Active anti-virus software can interfere with a firmware update process.[55] Any writeable firmware in the computer can be infected by malicious code.[56] This is a major concern, as an infected BIOS could require the actual BIOS chip to be replaced to ensure the malicious code is completely removed.[57] Anti-virus software is not effective at protecting firmware and the motherboard BIOS from infection.[58]

Adverse effects on system performance

By default, antivirus programs are designed to start automatically when the computer boots. Once they are running they are likely to run into communication and scanning conflicts, which cause the Antivirus to use large amounts of system memory, resulting in degraded computer performance.[citation needed]

Other methods

A command-line virus scanner, Clam AV 0.95.2, running a virus signature definition update, scanning a file and identifying a Trojan

Installed antivirus software running on an individual computer is only one method of guarding against viruses. Other methods are also used, including cloud-based antivirus, firewalls and on-line scanners.

Cloud antivirus

Cloud antivirus is a technology that uses lightweight agent software on the protected computer, while offloading the majority of data analysis to the provider's infrastructure.[59]

One approach to implementing cloud antivirus involves scanning suspicious files using multiple antivirus engines. This approach was proposed by an early implementation of the cloud antivirus concept called CloudAV. CloudAV was designed to send programs or documents to a network cloud where multiple antivirus and behavioral detection programs are used simultaneously in order to improve detection rates. Parallel scanning of files using potentially incompatible antivirus scanners is achieved by spawning a virtual machine per detection engine and therefore eliminating any possible issues. CloudAV can also perform "retrospective detection," whereby the cloud detection engine rescans all files in its file access history when a new threat is identified thus improving new threat detection speed. Finally, CloudAV is a solution for effective virus scanning on devices that lack the computing power to perform the scans themselves.[60]

Network firewall

Network firewalls prevent unknown programs and processes from accessing the system. However, they are not antivirus systems and make no attempt to identify or remove anything. They may protect against infection from outside the protected computer or network, and limit the activity of any malicious software which is present by blocking incoming or outgoing requests on certain TCP/IP ports. A firewall is designed to deal with broader system threats that come from network connections into the system and is not an alternative to a virus protection system.

Online scanning

Some antivirus vendors maintain websites with free online scanning capability of the entire computer, critical areas only, local disks, folders or files. Periodic online scanning is a good idea for those that run antivirus applications on their computers because those applications are frequently slow to catch threats. One of the first things that malicious software does in an attack is disable any existing antivirus software and sometimes the only way to know of an attack is by turning to an online resource that is not installed on the infected computer.[61]

Specialist tools

Using rkhunter to scan for rootkits on an Ubuntu Linux computer.

Virus removal tools are available to help remove stubborn infections or certain types of infection. Examples include Trend Micro's Rootkit Buster,[62] and rkhunter for the detection of rootkits, Avira's AntiVir Removal Tool,[63] PCTools Threat Removal Tool,[64] and AVG's Anti-Virus Free 2011.[65]

A rescue disk that is bootable, such as a CD or USB storage device, can be used to run antivirus software outside of the installed operating system, in order to remove infections while they are dormant. A bootable antivirus disk can be useful when, for example, the installed operating system is no longer bootable or has malware that is resisting all attempts to be removed by the installed antivirus software. Examples of some of these bootable disks include the Avira AntiVir Rescue System,[63] PCTools Alternate Operating System Scanner,[66] and AVG Rescue CD.[67] The AVG Rescue CD software can also be installed onto a USB storage device, that is bootable on newer computers.[67]

Popularity

According to an FBI survey, major businesses lose $12 million annually dealing with virus incidents.[68] A survey by Symantec in 2009 found that a third of small to medium sized business did not use antivirus protection at that time, whereas more than 80% of home users had some kind of antivirus installed.[69]

See also

References

  1. ^ "Softpedia Exclusive Interview: Avira 10". Ionut Ilascu. Softpedia. 14 April 2010. Retrieved 2011-09-11.
  2. ^ "Norton AntiVirus ignores malicious WMI instructions". Munir Kotadia. CBS Interactive. 21 October 2004. Retrieved 2009-04-05.
  3. ^ History of viruses
  4. ^ Kaspersky Lab Virus list
  5. ^ Wells, Joe (1996-08-30). "Virus timeline". IBM. Retrieved 2008-06-06.
  6. ^ G Data Software AG (2011). "G Data presents security firsts at CeBIT 2010". Retrieved 22 August 2011.
  7. ^ Karsmakers, Richard (2010). "The ultimate Virus Killer UVK 2000". Retrieved 22 August 2011. {{cite web}}: Unknown parameter |month= ignored (help)
  8. ^ Fred Cohen 1984 "Computer Viruses – Theory and Experiments"
  9. ^ Fred Cohen 1988 "On the implications of Computer Viruses and Methods of Defense"
  10. ^ a b Cohen, Fred, An Undetectable Computer Virus, 1987, IBM
  11. ^ VIRUS-L mailing list archive
  12. ^ Panda Security (2004). "(II) Evolution of computer viruses". Retrieved 2009-06-20. {{cite web}}: Unknown parameter |month= ignored (help)
  13. ^ Szor 2005, pp. 66–67
  14. ^ "New virus travels in PDF files". 7 August 2001. Retrieved 2011-10-29.
  15. ^ Slipstick Systems (2009). "Protecting Microsoft Outlook against Viruses". Retrieved 2009-06-18. {{cite web}}: Unknown parameter |month= ignored (help)
  16. ^ a b Landesman, Mary (2009). "What is a Virus Signature?". Retrieved 2009-06-18.
  17. ^ Szor 2005, pp. 474–481
  18. ^ Szor 2005, pp. 252–288
  19. ^ "Generic detection". Kaspersky. Retrieved 2009-02-24.
  20. ^ Symantec Corporation (2009). "Trojan.Vundo". Retrieved 2009-04-14. {{cite web}}: Unknown parameter |month= ignored (help)
  21. ^ Symantec Corporation (2007). "Trojan.Vundo.B". Retrieved 2009-04-14. {{cite web}}: Unknown parameter |month= ignored (help)
  22. ^ "Antivirus Research and Detection Techniques". ExtremeTech. Retrieved 2009-02-24.
  23. ^ Rootkit
  24. ^ Kelly, Michael (2006). "Buying Dangerously". Retrieved 2009-11-29. {{cite web}}: Unknown parameter |month= ignored (help)
  25. ^ Bitdefender (2009). "Automatic Renewal". Retrieved 2009-11-29.
  26. ^ Symantec (undated). "Ongoping Protection". Retrieved 2009-11-29. {{cite web}}: Check date values in: |year= (help)CS1 maint: year (link)
  27. ^ SpywareWarrior (2007). "Rogue/Suspect Anti-Spyware Products & Web Sites". Retrieved 2009-11-29.
  28. ^ Emil Protalinski (November 11, 2008). "AVG incorrectly flags user32.dll in Windows XP SP2/SP3". Ars Technica. Retrieved 2011-02-24. {{cite web}}: Italic or bold markup not allowed in: |publisher= (help)
  29. ^ Aaron Tan (May 24, 2007). "Flawed Symantec update cripples Chinese PCs". CNET Networks. Retrieved 2009-04-05. {{cite web}}: Italic or bold markup not allowed in: |publisher= (help)
  30. ^ a b David Harris (June 29, 2009). "January 2010 - Pegasus Mail v4.52 Release". Pegasus Mail. Retrieved 2010-05-21. {{cite web}}: Italic or bold markup not allowed in: |publisher= (help)
  31. ^ "McAfee DAT 5958 Update Issues". 21 April 2010. Retrieved 22 April 2010.
  32. ^ "Botched McAfee update shutting down corporate XP machines worldwide". 21 April 2010. Retrieved 22 April 2010.
  33. ^ John Leyden (December 2, 2010). "Horror AVG update ballsup bricks Windows 7". The Register. Retrieved 2010-12-02. {{cite web}}: Italic or bold markup not allowed in: |publisher= (help)
  34. ^ MSE false positive detection forces Google to update Chrome, retrieved Monday, 3 October 2011 {{citation}}: Check date values in: |accessdate= (help)
  35. ^ McAfee to compensate businesses for buggy update, retrieved Thursday, 2 December 2010 {{citation}}: Check date values in: |accessdate= (help)
  36. ^ Buggy McAfee update whacks Windows XP PCs, retrieved Thursday, 2 December 2010 {{citation}}: Check date values in: |accessdate= (help)
  37. ^ Microsoft (2007). "Plus! 98: How to Remove McAfee VirusScan". Retrieved 2009-11-29. {{cite web}}: Unknown parameter |month= ignored (help)
  38. ^ Robert Vamosi (May 28, 2009). "G-Data Internet Security 2010". PC World. Retrieved 2011-02-24. {{cite web}}: Italic or bold markup not allowed in: |publisher= (help)
  39. ^ Kelly Jackson Higgins (May 5, 2010). "New Microsoft Forefront Software Runs Five Antivirus Vendors' Engines". Darkreading. Retrieved 2011-02-24. {{cite web}}: Italic or bold markup not allowed in: |publisher= (help)
  40. ^ Microsoft (2009). "Steps to take before you install Windows XP Service Pack 3". Retrieved 2009-11-29. {{cite web}}: Unknown parameter |month= ignored (help)
  41. ^ "Upgrading from Windows Vista to Windows 7". Retrieved 24 March 2012. Mentioned within "Before you begin".
  42. ^ "Upgrading to Microsoft Windows Vista recommended steps". Retrieved 24 March 2012.
  43. ^ "How to troubleshoot problems during installation when you upgrade from Windows 98 or Windows Millennium Edition to Windows XP". Last Review: May 7, 2007. Retrieved 24 March 2012. {{cite web}}: Check date values in: |date= (help) Mentioned within "General troubleshooting".
  44. ^ "Troubleshooting". Retrieved 2011-02-17.
  45. ^ Field Notice: FN - 63204 - Cisco Clean Access has Interoperability issue with Symantec Anti-virus - delays Agent start-up
  46. ^ Dan Goodin (December 21, 2007). "Anti-virus protection gets worse". Channel Register. Retrieved 2011-02-24. {{cite web}}: Italic or bold markup not allowed in: |publisher= (help)
  47. ^ Dan Illett (July 13, 2007). "Hacking poses threats to business". Computer Weekly. Retrieved 2009-11-15. {{cite web}}: Italic or bold markup not allowed in: |publisher= (help)
  48. ^ AV Comparatives (2010). "Anti-Virus Comparative No. 25" (PDF). Retrieved 18 April 2010. {{cite web}}: Unknown parameter |month= ignored (help)
  49. ^ Guidelines released for antivirus software tests
  50. ^ Kotadia, Munir (2006). "Why popular antivirus apps 'do not work'". Retrieved 14 April 2010. {{cite web}}: Unknown parameter |month= ignored (help)
  51. ^ a b The Canadian Press (2010). "Internet scam uses adult game to extort cash". CBC News. Retrieved 17 April 2010. {{cite news}}: Unknown parameter |month= ignored (help)
  52. ^ Researchers up evilness ante with GPU-assisted malware - Coming to a PC near you, by Dan Goodin
  53. ^ GIBSON RESEARCH CORPORATION SERIES: Security Now!
  54. ^ "How Anti-Virus Software Works". Retrieved 2011-02-16.
  55. ^ "BT Home Hub Firmware Upgrade Procedure". Retrieved 2011-03-06.
  56. ^ "The 10 faces of computer malware". July 17, 2009. Retrieved 2011-03-06.
  57. ^ "New BIOS Virus Withstands HDD Wipes". Friday 27 March 2009. Retrieved 2011-03-06. {{cite web}}: Check date values in: |date= (help)
  58. ^ "Phrack Inc. Persistent BIOS Infection". June 1, 2009. Retrieved 2011-03-06.
  59. ^ Zeltser, Lenny (2010). "What Is Cloud Anti-Virus and How Does It Work?". Retrieved 2010-10-26. {{cite web}}: Unknown parameter |month= ignored (help)
  60. ^ Jon Erickson (August 6, 2008). "Antivirus Software Heads for the Clouds". Information Week. Retrieved 2010-02-24. {{cite web}}: Italic or bold markup not allowed in: |publisher= (help)
  61. ^ Brian Krebs (March 9, 2007). "Online Anti-Virus Scans: A Free Second Opinion". Washington Post. Retrieved 2011-02-24. {{cite web}}: Italic or bold markup not allowed in: |publisher= (help)
  62. ^ Ryan Naraine (February 2, 2007). "Trend Micro ships free 'rootkit buster'". ZDNet. Retrieved 2011-02-24. {{cite web}}: Italic or bold markup not allowed in: |publisher= (help)
  63. ^ a b Neil J. Rubenking (March 26, 2010). "Avira AntiVir Personal 10". PC Magazine. Retrieved 2011-02-24. {{cite web}}: Italic or bold markup not allowed in: |publisher= (help)
  64. ^ Neil J. Rubenking (September 16, 2010). "PC Tools Spyware Doctor with AntiVirus 2011". PC Magazine. Retrieved 2011-02-24. {{cite web}}: Italic or bold markup not allowed in: |publisher= (help)
  65. ^ Neil J. Rubenking (October 4, 2010). "AVG Anti-Virus Free 2011". PC Magazine. Retrieved 2011-02-24. {{cite web}}: Italic or bold markup not allowed in: |publisher= (help)
  66. ^ Neil J. Rubenking (November 19, 2009). "PC Tools Internet Security 2010". PC Magazine. Retrieved 2011-02-24. {{cite web}}: Italic or bold markup not allowed in: |publisher= (help)
  67. ^ a b Carrie-Ann Skinner (March 25, 2010). "AVG Offers Free Emergency Boot CD". PC World. Retrieved 2011-02-24. {{cite web}}: Italic or bold markup not allowed in: |publisher= (help)
  68. ^ "FBI estimates major companies lose $12m annually from viruses". 30 January 2007. Retrieved 20 February 2011.
  69. ^ Michael Kaiser (April 17, 2009). "Small and Medium Size Businesses are Vulnerable". National Cyber Security Alliance. Retrieved 2011-02-24. {{cite web}}: Italic or bold markup not allowed in: |publisher= (help)

Bibliography

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