Antivirus or anti-virus software (often abbreviated as AV ), sometimes known as anti-malware software, is computer software used to prevent, detect and remove malicious software . 
Antivirus software was originally developed to detect and remove computer viruses , hence the name. However, with the proliferation of other kinds of malware , antivirus software is starting to provide protection from other computer threats. In particular, modern antivirus software can protect from: malicious browser helper objects (BHOs), browser hijackers , ransomware , keyloggers , backdoors , rootkits , trojan horses , worms , malicious LSPs , dialers , fraudtools , adware andspyware .  Some products aussi include protection from other computer threats , Such As infected and malicious URLs , spam , scam and phishing attacks, online identity (privacy), online banking attacks, social engineering techniques, advanced persistent threat (APT) and botnet DDoS attacks. 
1949-1980 period (pre-antivirus days)
ALTHOUGH the roots of the computer virus dates back as early as 1949. When the Hungarian scientist John von Neumann published the “Theory of Self-Reproducing automata” ,  the first Known computer virus Appeared in 1971 and Was dubbed the ” Creeper virus “.  This computer virus infected Digital Equipment Corporation’s ( DEC ) PDP-10mainframe computers running the TENEX operating system.  
The Creeper virus was eventually released by Ray Tomlinson and known as “The Reaper”.  Some people consider “The Reaper” the first antivirus software ever written – it may be the case, but it is important to note that the Reaper is actually a virus that is specifically designed to remove the Creeper virus.   
The Creeper has been followed by several other viruses. The first known “appeared in the wild” was ” Elk Cloner “, in 1981, which infected Apple II computers.   
In 1983, the term “computer virus” was coined by Fred Cohen in one of the first ever published academic papers on computer viruses .  Cohen used the term “computer virus” to describe a program that: “affect other computer programs by modifying them in such a way to include a (possibly evolved) copy of itself.”  (note that a more recent, and precise, definition of computer virus by Pete Szőr : “a code that recursively replicates a possible evolved copy of itself”   )
The first IBM PC compatible “in the wild” computer virus, and one of the first widespread infections, was ” Brain ” in 1986. From then, the number of viruses has grown exponentially.   Most of the computer viruses were written in the early and mid-1980s were limited to self-reproduction and had no specific damage routine built into the code. That changed when more programmers became acquainted with computer viruses and created viruses that were manipulated or even destroyed. 
Before internet connectivity was widespread, computer viruses were typically spread by infected floppy disks . Antivirus software came into use, but was updated relatively infrequently. During this time, most of the time, the virus checkers had to check executable files and the boot sectors of floppy disks and hard disks. However, the use of Internet has become common, viruses began to spread online. 
1980-1990 period (early days)
There are competing claims for the innovator of the first antivirus product. Possibly, the first year Publicly documented removal of “in the wild” computer viruses (ie the “Vienna virus”) Was Performed by Bernd Fix in 1987.  
In 1987, Andreas Lüning and Kai Figge founded G Data Software and released their first antivirus product for the Atari ST platform.  Dubiously, they later also produced Virus Construction Kits.  In 1987, the Ultimate Virus Killer (UVK) was also released.  This was the de facto industry standard killer virus for the Atari ST and Atari Falcon , the last version of which (version 9.0) was released in April 2004. [ citation needed ] In 1987, in the United States, John McAfee was founded the McAfee company (now part ofIntel Security  and, at the end of that year, he released the first version of VirusScan .  Also in 1987 (in Czechoslovakia ), Peter Paško, Rudolf Hrubý, and Miroslav Trnka created the first version of NOD antivirus.  
In 1987, Fred Cohen wrote that there is no algorithm that can not detect all possible computer viruses . 
Finally, at the end of 1987, the first two heuristic antivirus utilities were released: Flushot Plus by Ross Greenberg    and Anti4us by Erwin Lanting.  In his O’Reilly book, Malicious Mobile Code: Virus Protection for Windows, Roger Grimes describes Flushot Plus as “the first holistic program to fight MMC [malicious mobile code].” 
However, the kind of heuristic used by early AV engines was totally different from those used today. The first product with a heuristic engine resembling modern ones was F-PROT in 1991. Data section, code section (in a legitimate binary, it usually starts from the same location). Indeed, the initial viruses re-organized the layout of the sections, or overrode the initial portion of section in order to jump to the end of where the code was located. This is a very specific pattern, which is an elegant heuristic to catch a suspicious code. Other types of more advanced heuristics were added, such as suspicious section names, incorrect header size, regular expressions, and partial pattern in-memory matching.
In 1988, the growth of antivirus companies continued. In Germany, Tjark Auerbach founded Avira ( H + BEDV at the time) and released the first version of AntiVir (named “Luke Filewalker” at the time). In Bulgaria , Dr. Vesselin Bontchev released his first freeware antivirus program (later FRISK Software ). Also Frans Veldman released the first version of ThunderByte Antivirus , also known as TBAV (he sold his company to Norman Safeground in 1998). In Czechoslovakia , Pavel Baudiš and Eduard Kučera started avast! (at the time ALWIL Software) and released their first version of avast! anti-virus. In June 1988, in South Korea , Dr. Ahn Cheol-Soo released its first antivirus software, called V1 (he founded AhnLab later in 1995). Finally, in the Autumn 1988, in United Kingdom, Alan Solomon founded S & S International and created his own Dr. Solomon’s Anti-Virus Toolkit (in which case it was launched in 1991 – in 1998 Dr. Solomon’s was acquired by McAfee). In November 1988 a professor at the Panamerican University in Mexico City named Alejandro E. Carriles copyrighted the first antivirus software in Mexico under the name “Byte Matabichos” (Byte Bugkiller) to help solve the rampant virus infestation among students. 
Also in 1988, a mailing list named VIRUS-L  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 were: Alan Solomon, Eugene Kaspersky ( Kaspersky Lab ), Friðrik Skúlason ( FRISK Software ), John McAfee ( McAfee ), Luis Corrons ( Panda Security ), Mikko Hyppönen ( F-Secure ), Peter Szőr , Tjark Auerbach ( Avira ) and Dr. Vesselin Bontchev ( FRISK Software). 
In 1989, in Iceland , Friðrik Skúlason created the first version of F-PROT Anti-Virus back in 1989 (he founded FRISK Software only in 1993). In the meanwhile, in United States, Symantec (founded by Gary Hendrix in 1982) launched its first Symantec antivirus for Macintosh (SAM).   SAM 2.0, released March 1990, authored SAM to intercept and eliminate new viruses, including many that did not exist at the time of the program’s release. 
In the end of the 1980s, in United Kingdom, Jan Hruska and Lammer Peter founded the security firm Sophos and their first production antivirus and encryption products. In the same period, in Hungary, also VirusBuster was founded (which has recently been incorporated by Sophos ).
1990-2000 period (emergence of the antivirus industry)
In 1990, in Spain, Mikel Urizarbarrena founded Panda Security ( Panda Software at the time).  In Hungary, the security researcher Péter Szőr released the first version of Pasteur antivirus. In Italy, Gianfranco Tonello created the first version of VirIT eXplorer antivirus (he founded TG Soft one year later). 
In 1990, the Computer Antivirus Research Organization ( CARO ) was founded. In 1991, CARO released the “Virus Naming Scheme” , originally written by Friðrik Skúlason and Vesselin Bontchev.  Although this naming scheme is now obsolete, it remains the only existing standard to adopt. CARO members includes: Alan Solomon, Costin Raiu, Dmitry Gryaznov, Eugene Kaspersky , Friðrik Skúlason , Igor Muttik , Mikko Hyppönen, Morton Swimmer, Nick FitzGerald, Padgett Peterson, Peter Ferrie, Righard Zwienenberg, and Dr. Vesselin Bontchev.  
In 1991, in the United States, Symantec released the first version of Norton AntiVirus . In the same year, in the Czech Republic , Jan Gritzbach and Tomáš Hofer founded AVG Technologies ( Grisoft at the time), but they released the first version of their Anti-Virus Guard (AVG) only in 1992. On the other hand, in Finland , F-Secure (Founded in 1988 by Petri Allas and Risto Siilasmaa – with the name of Data Fellows) released the first version of their antivirus product. F-Secure claims to be the first antivirus firm to establish a presence on the World Wide Web. 
In 1991, the European Institute for Computer Antivirus Research ( EICAR ) was founded to further develop antivirus and antivirus software.  
In 1992, in Russia, Igor Danilov released the first version of SpiderWeb , which later became Dr. Web . 
In 1994, AV-TEST reported that there were 28,613 unique malware samples (based on MD5) in their database. 
Over time other companies were founded. In 1996, in Romania , Bitdefender was founded and released the first version of Anti-Virus eXpert (AVX).  In 1997, in Russia, Eugene Kaspersky and Natalia Kaspersky co-founded security firm Kaspersky Lab . 
In 1996, there was also the first “in the wild” Linux virus, known as ” Staog “ . 
In 1999, AV-TEST reported that there were 98,428 unique malware samples (based on MD5) in their database. 
In 2000, Rainer Link and Howard Fuh started the first open source antivirus engine, called OpenAntivirus Project . 
In 2001, Tomasz Kojm released the first version of ClamAV , the first ever open source antivirus engine to be commercialized. In 2007, ClamAV was bought by Sourcefire ,  which in turn was acquired by Cisco Systems in 2013. 
In 2002, Morten Lund and Theis Søndergaard co-founded the antivirus firm BullGuard. 
In 2005, AV-TEST reported that there were 333,425 unique malware samples (based on MD5) in their database. 
2005 to 2014 period
In 2007, AV-TEST reported a number of 5,490,960 new unique malware samples (based on MD5) only for that year.  In 2012 and 2013, antivirus firms reported a new malware samples range from 300,000 to over 500,000 per day.  
Multiple detection strategies and detection algorithms, rather than just executables, for more reasons :
- Powerful macros used in word processor applications, such as Microsoft Word , presented a risk. Virus writers could use the macro to write viruses embedded within documents. This means that computers could be at risk of becoming infected with macros. 
- The possibility of embedding executable objects inside otherwise non-executable file formats 
- 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. 
In 2005, F-Secure was the first security firm that developed Anti-Rootkit technology, called BlackLight .
Given the fact that most of the people are nowadays connected to the Internet round-the-clock, in 2008, Jon Oberheide first proposed a Cloud-based antivirus design. 
In February 2008 McAfee Labs added the industry-first cloud-based anti-malware feature to VirusScan under Artemis name. It was tested by AV-Comparatives in February 2008  and officially unveiled in August 2008 in McAfee VirusScan . 
Cloud computing created problems for the analysis of security software – part of the definition of the AV company (s) thus making non-repeatable results. As a result, the Anti-Malware Testing Standards Organization ( AMTSO ) was launched on May 7, 2009. 
In 2011, AVG introduced a similar cloud service called Protective Cloud Technology. 
2014 to present (rise of next-gen)
More recently, following the 2014 release of the APT 1 report from Mandiant, the industry has seen a shift towards signature-less approaches to the problem capable of detecting and mitigating zero-day attacks. Numerous approaches to address these new forms of threats have appeared, including behavioral detection, artificial intelligence, machine learning, and cloud-based file detonation. According to Gartner, it is expected the rise of new entrants, such Carbon Black, Cylance and Crowdstrike will force EPP incumbents into a new phase of innovation and acquisition. One method from Bromium involves micro-virtualization to protect desktops from malicious code execution initiated by the end user. Another approach from SentinelOne and Carbon Black focuses on behavioral detection by building a full context around every process execution path in real time, while Cylance leverages an artificial intelligence model based on machine learning. Increasingly, these signature-less approaches have been defined by the media and analyst firms as “next-generation” antivirus and are seeing rapid market adoption as certified antivirus replacement technologies by firms such as Coalfire and DirectDefense. In response, traditional antivirus vendors such as Trend Micro, Symantec and Sophos have responded by incorporating “next-gen” offerings into their portfolios as analyst firms such as Forrester and Gartner have called traditional signature-based antivirus “ineffective” and “outdated”.
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. However, using different layers of defense, a good detection rate may be achieved.
There are several methods which antivirus engine can use to identify malware:
- Sandbox detection: is a particular behavioural-based detection technique that, instead of detecting the behavioural fingerprint at run time, it executes the programs in a virtual environment, logging what actions the program performs. Depending on the actions logged, the antivirus engine can determine if the program is malicious or not. If not, then, the program is executed in the real environment. Albeit this technique has shown to be quite effective, given its heaviness and slowness, it is rarely used in end-user antivirus solutions.
- Data mining techniques: are one of the latest approach applied in malware detection. Data mining and machine learning algorithms are used to try to classify the behaviour of a file (as either malicious or benign) given a series of file features, that are extracted from the file itself.
Traditional antivirus software relies heavily upon signatures to identify malware.
Substantially, when a malware arrives in the hands of an antivirus firm, it is analyzed by malware researchers or by dynamic analysis systems. Then, it is determined to be a malware, a proper signature of the file is extracted and added to the signatures database of the antivirus software. 
Although the signature-based approach has been made by the authors of ” oligomorphic “, ” polymorphic ” and, more recently, ” metamorphic ” viruses, which encrypt parts of themselves or otherwise modify themselves as a method of disguise, so do not match virus signatures in the dictionary. 
Many viruses start as a single infection and through Either mutation gold Refinements by other attackers, can grow into Dozens of Slightly different strains, called Expired variants. Generic detection refers to the detection and removal of multiple threats using a single virus definition. 
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 separate categories, Trojan.Vundo and Trojan.Vundo.B .  
While it may be advantageous to identify a specific virus, it can be detected by a generic signature or an inexact match to an existing signature. Virus researchers find common areas that all viruses in a family share uniquely and thus can 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.  A detection that uses this method is said to be “heuristic detection.”
Anti-virus software can be used to scan for rootkits. A rootkit is a type of malware designed to gain administrative-level control over a computer system without being detected. Rootkits can change 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. 
Real-time protection, anti-spyware, anti-spyware, anti-spyware and other anti-malware programs. Computer monitors, spyware, adware, and other malicious objects in ‘real-time’, in other words while data is loaded into the computer’s active memory: when inserting a CD, opening an email, or browsing the web, or when a file is already installed. 
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 subscribe to at least 60 days before the expiration of the present subscription  while BitDefender sends notifications to unsubscribe 30 days before the renewal.  Norton AntiVirus also renews subscriptions automatically by default. 
Rogue security applications
Some antivirus programs are apparent Actually malware masquerading as legitimate software, Such As winfixer , MS Antivirus , and Mac Defender . 
Problems caused by false positives
A “false positive” or “false alarm” is when antivirus software is identified as non-malicious file as malware. When this happens, it can cause serious problems. For example, if an antivirus program is configured to immediately delete or quarantine infected files, as it is common to Microsoft Windows antivirus applications, a false positive in an essential file can render the Windows operating system or some applications unusable.  Recovering from such damage to critical software infrastructure and operations is undertaken.   For example, in May 2007 a faulty virus signature issued by Symantecmistakenly removed essential operating system files, leaving thousands of PCs will not boot . 
Also in May 2007, the executable file required by Pegasus Mail on Windows Was falsely detected by Norton AntiVirus as being white and a Trojan It was automatically removed, Preventing Pegasus Mail from running. Norton AntiVirus had been falsely identified from Pegasus Mail as malware, and would delete the Pegasus Mail install file when that happened.  In response to this Pegasus Mail stated:
|“||On the basis that Norton / Symantec has done for this one of the last three releases of Pegasus Mail, we can only condemn this product as too flawed to use, and recommend it in the strongest terms that our users cease using it in favor of alternative , less buggy anti-virus packages. ||“|
In April 2010, McAfee VirusScan detected svchost.exe, a normal Windows binary, has a virus on Windows XP running machines with Service Pack 3, causing a reboot loop and loss of all network access.  
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. 
In October 2011, Microsoft Security Essentials (MSE) removed the Google Chrome web browser, rivaling Microsoft’s own Internet Explorer . MSE flagged Chrome as a Zbot banking trojan . 
In September 2012, Sophos ‘ anti-virus suite identified various update-mechanisms, including its own, as malware. If it was configured to automatically delete detected files, Sophos Antivirus could make it unable to update, required manual to fix the problem.  
In September 2017, the Google Play Protect anti-virus started identifying Motorola’s G4 bluetooth application as malware, causing bluetooth functionality to become disabled. 
System and interoperability related issues
Running (the real-time protection of) multiple antivirus programs competitor can degrade performance and create conflicts.  However, using a concept called multiscanning , several companies (including G Data Software  and Microsoft  ) have created applications that can run multiple concurrently engines.
It is sometimes necessary to maintain Windows service packs or update graphics card drivers.  Active antivirus protection can partially or completely prevent the installation of a major update. Anti-virus software can cause problems during the installation of an operating system upgrade, eg 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.   
The functionality of a few computer programs can be hampered by active anti-virus software. For example, TrueCrypt , a disk encryption program, which can be used to troubleshoot malware.  Anti-virus software can the odd performance and stability of running games in the Steam platform. 
Support issues also exist around antivirus application interoperability with common solutions like remote access VPN and network access control products.  These technologies solutions that require an up-to-date antivirus is installed and running. If the antivirus application is not recognized by the policy assessment, the virus will not be able to connect.
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% .  According to the ZeuS tracker website, the average detection rate for all variants of the known ZeuS trojan is as low as 40%. 
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, by amateurs, exhibited destructive behavior or pop-ups . Modern viruses are often written by professionals, financed by criminal organizations . 
In 2008, Eva Chen , CEO of Trend Micro , stated that the anti-virus industry has been misleading customers for years. 
Independent virus testing provides the best virus scanners that provide 100% virus detection. The best ones provided as high as 99.9% detection for simulated real-world situations, while the lowest provided 91.1% in tests conducted in August 2013. Many virus scanners produce false positive results as well, identifying benign files as malware. 
Av -Comparatives , ICSA Labs , West Coast Labs, Virus Bulletin , AV-TEST and other members of the Anti-Malware Testing Standards Organization .  
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 they are not detected before releasing them into the wild. 
Some new viruses, particularly ransomware , use a polymorphic code to avoid detection by virus scanners. Jerome Segura, a security analyst with ParetoLogic, explained: 
|“||It’s something that they miss a lot of the time because of this type of [ransomware virus] that comes from the fact that they have a polymorphism, which means they basically get to the root of the virus. I’ve seen people 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, and you’re never really sure if it’s really gone.When we see something that we usually recommend to install the operating system or reinstall backups. ||“|
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 analyze the inner workings of Such malware. 
Detecting rootkits is a major challenge for anti-virus programs. Rootkits have full 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 and tamper with antivirus programs. 
If a file has been infected by a computer virus, anti-virus software will attempt to remove the virus code from the file during disinfection, but it is not always able to restore the file to its undamaged state.   In such circumstances, such files may be restored by existing backups or shadow copies (this is also true for ransomware  ); installed software that is damaged requires re-installation  (however, see System File Checker ).
Active anti-virus software can interfere with a firmware update process.  Any writeable firmware in the computer can be infected by malicious code.  This is a major concern, as it was infected BIOS could require the current BIOS chip to be replaced to ensure the malicious code is completely removed.  Anti-virus software is not effective at protecting firmware and the BIOS motherboard from infection.  In 2014, security researchers discovered that USB devices contain writeable firmware that can be modified with malicious code (dubbed ” BadUSB”), which anti-virus software can not detect or prevent.  
Performance and other drawbacks
Antivirus software has some drawbacks, first of which it can impact a computer’s performance . 
Furthermore, inexperienced users can be misled into a false sense of security when using the computer, and they may be susceptible to having problems with the software. An incorrect decision may lead to a breach of security. If the antivirus software employees heuristic detection, it must be fine-tuned to minimize misidentifying harmless software as malicious ( false positive ). 
Antivirus software Itself usually runs at the highly trusted kernel level of the operating system to allow it access to all the potential malicious processes and files, Creating a potential avenue of attack .  The UK and US intelligence agencies, GCHQ and the National Security Agency (NSA), respectively, have been exploiting anti-virus software to spy on users.  Anti-virus software has highly privileged and trusted access to the underlying operating system, which makes it much more appealing for remote attacks. Anti-virus software is “years behind security-conscious client-side applications like browsers or document readers”, according to Joxean Koret, a researcher with Coseinc, a Singapore-based information security consultancy. 
Installed antivirus solutions, running on individual computers, the most used, is only one method of guarding against malware. Other alternative solutions are also used, including: Unified Threat Management ( UTM ), hardware and network firewalls, cloud-based antivirus and on-line scanners.
Hardware and 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.
Antivirus Cloud is a technology that uses lightweight software on the protected computer, while offloading the majority of data to the provider’s infrastructure. 
One approach to implementing cloud antivirus involves scanning suspicious files using multiple antivirus engines. This approach was proposed by the early implementation of the cloud antivirus concept called CloudAV. CloudAV was designed to send programs or documents to a network cloudwhere multiple antivirus and behavioral detection programs are used. Parallel scanning of files using potentially incompatible antivirus scanners is achieved by spawning a virtual machine. CloudAV can also perform “retrospective detection,” means the cloud detection engine rescues all files in its file access. Finally, CloudAV is a solution for effective virus scanning on devices that lack the computing power to perform the scans themselves. 
Some examples of cloud anti-virus products are Panda Cloud Antivirus , Crowdstrike , Cb Defense and Immunet . Comodo group has also produced cloud-based anti-virus.  
Some antivirus vendors maintain websites with free online scanning capabilities of the entire computer, critical areas only, local disks, folders or files. Periodic online scanning is a good idea for those who run an antivirus. One of the first things that make it difficult to attack an infected virus. 
Virus removal tools are available to help remove stubborn infections or certain types of infection. Examples include Trend Micro ‘s Rootkit Buster ,  and rkhunter for the detection of rootkits , Avira ‘s AntiVir Removal Tool ,  PCTools Threat Removal Tool ,  and AVG ‘s Anti-Virus Free 2011 [164 ]
A rescue disk that is bootable, such as a CD or USB storage device, can be used to run an 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 software is not used. Examples of some of these bootable disks include the Avira AntiVir Rescue System , PCTools Alternate Operating System Scanner ,  and AVG Rescue CD . The AVG Rescue CD software can also be installed on a USB storage device, which is bootable on newer computers. 
Usage and risks
According to an FBI survey, major businesses lose $ 12 million annually dealing with virus incidents.  A survey by Symantec in 2009 found that a third of small-medium-sized business did not use antivirus protection at that time, with more than 80% of home users having some kind of antivirus installed.  According to a sociological survey conducted by G Data Software in 2010 49% of women did not use any antivirus program at all.