Malware (a portmanteau for malicious software) is any software intentionally designed to cause damage to a computer, server, client, or computer network (by contrast, software that causes unintentional harm due to some deficiency is typically described as a software bug). A wide variety of types of malware exist, including computer viruses, worms, Trojan horses, ransomware, spyware, adware, and scareware.
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Programs are also considered malware if they secretly act against the interests of the computer user. For example, at one point Sony music Compact discs silently installed a rootkit on purchasers' computers with the intention of preventing illicit copying, but which also reported on users' listening habits, and unintentionally created extra security vulnerabilities.
A range of antivirus software, firewalls and other strategies are used to help protect against the introduction of malware, to help detect it if it is already present, and to recover from malware-associated malicious activity and attacks.
Many early infectious programs, including the first Internet Worm, were written as experiments or pranks. Today, malware is used by both black hat hackers and governments, to steal personal, financial, or business information.
Malware is sometimes used broadly against government or corporate websites to gather guarded information, or to disrupt their operation in general. However, malware can be used against individuals to gain information such as personal identification numbers or details, bank or credit card numbers, and passwords.
Since the rise of widespread broadband Internet access, malicious software has more frequently been designed for profit. Since 2003, the majority of widespread viruses and worms have been designed to take control of users' computers for illicit purposes. Infected "zombie computers" can be used to send email spam, to host contraband data such as child pornography, or to engage in distributed denial-of-service attacks as a form of extortion.
Programs designed to monitor users' web browsing, display unsolicited advertisements, or redirect affiliate marketing revenues are called spyware. Spyware programs do not spread like viruses; instead they are generally installed by exploiting security holes. They can also be hidden and packaged together with unrelated user-installed software. The Sony BMG rootkit was intended to prevent illicit copying; but also reported on users' listening habits, and unintentionally created extra security vulnerabilities.
Ransomware affects an infected computer system in some way, and demands payment to bring it back to its normal state. There are two variations of ransomware, being crypto ransomware and locker ransomware. With the locker ransomware just locking down a computer system without encrypting its contents. Whereas the traditional ransomware is one that locks down your system and encrypts the contents of the system. For example, programs such as CryptoLocker encrypt files securely, and only decrypt them on payment of a substantial sum of money.
Some malware is used to generate money by click fraud, making it appear that the computer user has clicked an advertising link on a site, generating a payment from the advertiser. It was estimated in 2012 that about 60 to 70% of all active malware used some kind of click fraud, and 22% of all ad-clicks were fraudulent.
In addition to criminal money-making, malware can be used for sabotage, often for political motives. Stuxnet, for example, was designed to disrupt very specific industrial equipment. There have been politically motivated attacks that have spread over and shut down large computer networks, including massive deletion of files and corruption of master boot records, described as "computer killing." Such attacks were made on Sony Pictures Entertainment (25 November 2014, using malware known as Shamoon or W32.Disttrack) and Saudi Aramco (August 2012).
The best-known types of malware, viruses and worms, are known for the manner in which they spread, rather than any specific types of behavior. A computer virus is software that embeds itself in some other executable software (including the operating system itself) on the target system without the user's knowledge and consent and when it is run, the virus is spread to other executables. On the other hand, a worm is a stand-alone malware software that actively transmits itself over a network to infect other computers. These definitions lead to the observation that a virus requires the user to run an infected software or operating system for the virus to spread, whereas a worm spreads itself.
A computer virus is software usually hidden within another seemingly innocuous program that can produce copies of itself and insert them into other programs or files, and that usually performs a harmful action (such as destroying data). An example of this is a PE infection, a technique, usually used to spread malware, that inserts extra data or executable code into PE files.
'Lock-screens', or screen lockers is a type of “cyber police” ransomware that blocks screens on Windows or Android devices with a false accusation in harvesting illegal content, trying to scare the victims into paying up a fee. Jisut and SLocker impact Android devices more than other lock-screens, with Jisut making up nearly 60 percent of all Android ransomware detections.
A Trojan horse is a harmful program that misrepresents itself to masquerade as a regular, benign program or utility in order to persuade a victim to install it. A Trojan horse usually carries a hidden destructive function that is activated when the application is started. The term is derived from the Ancient Greek story of the Trojan horse used to invade the city of Troy by stealth.
Trojan horses are generally spread by some form of social engineering, for example, where a user is duped into executing an e-mail attachment disguised to be unsuspicious, (e.g., a routine form to be filled in), or by drive-by download. Although their payload can be anything, many modern forms act as a backdoor, contacting a controller which can then have unauthorized access to the affected computer. While Trojan horses and backdoors are not easily detectable by themselves, computers may appear to run slower due to heavy processor or network usage.
In spring 2017 Mac users were hit by the new version of Proton Remote Access Trojan (RAT) trained to extract password data from various sources, such as browser auto-fill data, the Mac-OS keychain, and password vaults.
Once malicious software is installed on a system, it is essential that it stays concealed, to avoid detection. Software packages known as rootkits allow this concealment, by modifying the host's operating system so that the malware is hidden from the user. Rootkits can prevent a harmful process from being visible in the system's list of processes, or keep its files from being read.
Some types of harmful software contain routines to evade identification and/or removal attempts, not merely to hide themselves. An early example of this behavior is recorded in the Jargon File tale of a pair of programs infesting a Xerox CP-V time sharing system:
A backdoor is a method of bypassing normal authentication procedures, usually over a connection to a network such as the Internet. Once a system has been compromised, one or more backdoors may be installed in order to allow access in the future, invisibly to the user.
The idea has often been suggested that computer manufacturers preinstall backdoors on their systems to provide technical support for customers, but this has never been reliably verified. It was reported in 2014 that US government agencies had been diverting computers purchased by those considered "targets" to secret workshops where software or hardware permitting remote access by the agency was installed, considered to be among the most productive operations to obtain access to networks around the world. Backdoors may be installed by Trojan horses, worms, implants, or other methods.
- evasion of analysis and detection by fingerprinting the environment when executed.
- confusing automated tools' detection methods. This allows malware to avoid detection by technologies such as signature-based antivirus software by changing the server used by the malware.
- timing-based evasion. This is when malware runs at certain times or following certain actions taken by the user, so it executes during certain vulnerable periods, such as during the boot process, while remaining dormant the rest of the time.
- obfuscating internal data so that automated tools do not detect the malware.
Nowadays, one of the most sophisticated and stealthy ways of evasion is to use information hiding techniques, namely stegomalware. A survey on stegomalware was published by Cabaj et al. in 2018.
- In this context, and throughout, what is called the "system" under attack may be anything from a single application, through a complete computer and operating system, to a large network.
- Various factors make a system more vulnerable to malware:
Security defects in software
Malware exploits security defects (security bugs or vulnerabilities) in the design of the operating system, in applications (such as browsers, e.g. older versions of Microsoft Internet Explorer supported by Windows XP), or in vulnerable versions of browser plugins such as Adobe Flash Player, Adobe Acrobat or Reader, or Java SE. Sometimes even installing new versions of such plugins does not automatically uninstall old versions. Security advisories from plug-in providers announce security-related updates. Common vulnerabilities are assigned CVE IDs and listed in the US National Vulnerability Database. Secunia PSI is an example of software, free for personal use, that will check a PC for vulnerable out-of-date software, and attempt to update it.
Malware authors target bugs, or loopholes, to exploit. A common method is exploitation of a buffer overrun vulnerability, where software designed to store data in a specified region of memory does not prevent more data than the buffer can accommodate being supplied. Malware may provide data that overflows the buffer, with malicious executable code or data after the end; when this payload is accessed it does what the attacker, not the legitimate software, determines.
Insecure design or user error
Early PCs had to be booted from floppy disks. When built-in hard drives became common, the operating system was normally started from them, but it was possible to boot from another boot device if available, such as a floppy disk, CD-ROM, DVD-ROM, USB flash drive or network. It was common to configure the computer to boot from one of these devices when available. Normally none would be available; the user would intentionally insert, say, a CD into the optical drive to boot the computer in some special way, for example, to install an operating system. Even without booting, computers can be configured to execute software on some media as soon as they become available, e.g. to autorun a CD or USB device when inserted.
Malware distributors would trick the user into booting or running from an infected device or medium. For example, a virus could make an infected computer add autorunnable code to any USB stick plugged into it. Anyone who then attached the stick to another computer set to autorun from USB would in turn become infected, and also pass on the infection in the same way. More generally, any device that plugs into a USB port - even lights, fans, speakers, toys, or peripherals such as a digital microscope - can be used to spread malware. Devices can be infected during manufacturing or supply if quality control is inadequate.
This form of infection can largely be avoided by setting up computers by default to boot from the internal hard drive, if available, and not to autorun from devices. Intentional booting from another device is always possible by pressing certain keys during boot.
Over-privileged users and over-privileged code
In computing, privilege refers to how much a user or program is allowed to modify a system. In poorly designed computer systems, both users and programs can be assigned more privileges than they should have, and malware can take advantage of this. The two ways that malware does this is through overprivileged users and overprivileged code.
Some systems allow all users to modify their internal structures, and such users today would be considered over-privileged users. This was the standard operating procedure for early microcomputer and home computer systems, where there was no distinction between an administrator or root, and a regular user of the system. In some systems, non-administrator users are over-privileged by design, in the sense that they are allowed to modify internal structures of the system. In some environments, users are over-privileged because they have been inappropriately granted administrator or equivalent status.
Some systems allow code executed by a user to access all rights of that user, which is known as over-privileged code. This was also standard operating procedure for early microcomputer and home computer systems. Malware, running as over-privileged code, can use this privilege to subvert the system. Almost all currently popular operating systems, and also many scripting applications allow code too many privileges, usually in the sense that when a user executes code, the system allows that code all rights of that user. This makes users vulnerable to malware in the form of e-mail attachments, which may or may not be disguised.
Use of the same operating system
- Homogeneity can be a vulnerability. For example, when all computers in a network run the same operating system, upon exploiting one, one worm can exploit them all: In particular, Microsoft Windows or Mac OS X have such a large share of the market that an exploited vulnerability concentrating on either operating system could subvert a large number of systems. Introducing diversity purely for the sake of robustness, such as adding Linux computers, could increase short-term costs for training and maintenance. However, as long as all the nodes are not part of the same directory service for authentication, having a few diverse nodes could deter total shutdown of the network and allow those nodes to help with recovery of the infected nodes. Such separate, functional redundancy could avoid the cost of a total shutdown, at the cost of increased complexity and reduced usability in terms of single sign-on authentication.
As malware attacks become more frequent, attention has begun to shift from viruses and spyware protection, to malware protection, and programs that have been specifically developed to combat malware. (Other preventive and recovery measures, such as backup and recovery methods, are mentioned in the computer virus article).
Anti-virus and anti-malware software
A specific component of anti-virus and anti-malware software, commonly referred to as an on-access or real-time scanner, hooks deep into the operating system's core or kernel and functions in a manner similar to how certain malware itself would attempt to operate, though with the user's informed permission for protecting the system. Any time the operating system accesses a file, the on-access scanner checks if the file is a 'legitimate' file or not. If the file is identified as malware by the scanner, the access operation will be stopped, the file will be dealt with by the scanner in a pre-defined way (how the anti-virus program was configured during/post installation), and the user will be notified. This may have a considerable performance impact on the operating system, though the degree of impact is dependent on how well the scanner was programmed. The goal is to stop any operations the malware may attempt on the system before they occur, including activities which might exploit bugs or trigger unexpected operating system behavior.
Anti-malware programs can combat malware in two ways:
- They can provide real time protection against the installation of malware software on a computer. This type of malware protection works the same way as that of antivirus protection in that the anti-malware software scans all incoming network data for malware and blocks any threats it comes across.
- Anti-malware software programs can be used solely for detection and removal of malware software that has already been installed onto a computer. This type of anti-malware software scans the contents of the Windows registry, operating system files, and installed programs on a computer and will provide a list of any threats found, allowing the user to choose which files to delete or keep, or to compare this list to a list of known malware components, removing files that match.
Real-time protection from malware works identically to real-time antivirus protection: the software scans disk files at download time, and blocks the activity of components known to represent malware. In some cases, it may also intercept attempts to install start-up items or to modify browser settings. Because many malware components are installed as a result of browser exploits or user error, using security software (some of which are anti-malware, though many are not) to "sandbox" browsers (essentially isolate the browser from the computer and hence any malware induced change) can also be effective in helping to restrict any damage done.
Examples of Microsoft Windows antivirus and anti-malware software include the optional Microsoft Security Essentials (for Windows XP, Vista, and Windows 7) for real-time protection, the Windows Malicious Software Removal Tool (now included with Windows (Security) Updates on "Patch Tuesday", the second Tuesday of each month), and Windows Defender (an optional download in the case of Windows XP, incorporating MSE functionality in the case of Windows 8 and later). Additionally, several capable antivirus software programs are available for free download from the Internet (usually restricted to non-commercial use). Tests found some free programs to be competitive with commercial ones. Microsoft's System File Checker can be used to check for and repair corrupted system files.
Some viruses disable System Restore and other important Windows tools such as Task Manager and Command Prompt. Many such viruses can be removed by rebooting the computer, entering Windows safe mode with networking, and then using system tools or Microsoft Safety Scanner.
Hardware implants can be of any type, so there can be no general way to detect them.
Website security scans
As malware also harms the compromised websites (by breaking reputation, blacklisting in search engines, etc.), some websites offer vulnerability scanning. Such scans check the website, detect malware, may note outdated software, and may report known security issues.
"Air gap" isolation or "parallel network"
As a last resort, computers can be protected from malware, and infected computers can be prevented from disseminating trusted information, by imposing an "air gap" (i.e. completely disconnecting them from all other networks). However, malware can still cross the air gap in some situations. For example, removable media can carry malware across the gap.
It describes applications that behave in an annoying or undesirable manner, and yet are less serious or troublesome than malware. Grayware encompasses spyware, adware, fraudulent dialers, joke programs, remote access tools and other unwanted programs that may harm the performance of computers or cause inconvenience. The term came into use around 2004.
Another term, potentially unwanted program (PUP) or potentially unwanted application (PUA), refers to applications that would be considered unwanted despite often having been downloaded by the user, possibly after failing to read a download agreement. PUPs include spyware, adware, and fraudulent dialers. Many security products classify unauthorised key generators as grayware, although they frequently carry true malware in addition to their ostensible purpose.
Software maker Malwarebytes lists several criteria for classifying a program as a PUP. Some types of adware (using stolen certificates) turn off anti-malware and virus protection; technical remedies are available.
History of viruses and worms
Before Internet access became widespread, viruses spread on personal computers by infecting executable programs or boot sectors of floppy disks. By inserting a copy of itself into the machine code instructions in these programs or boot sectors, a virus causes itself to be run whenever the program is run or the disk is booted. Early computer viruses were written for the Apple II and Macintosh, but they became more widespread with the dominance of the IBM PC and MS-DOS system. The first IBM PC virus in the "wild" was a boot sector virus dubbed (c)Brain, created in 1986 by the Farooq Alvi brothers in Pakistan. Executable-infecting viruses are dependent on users exchanging software or boot-able floppies and thumb drives so they spread rapidly in computer hobbyist circles.
The first worms, network-borne infectious programs, originated not on personal computers, but on multitasking Unix systems. The first well-known worm was the Internet Worm of 1988, which infected SunOS and VAX BSD systems. Unlike a virus, this worm did not insert itself into other programs. Instead, it exploited security holes (vulnerabilities) in network server programs and started itself running as a separate process. This same behavior is used by today's worms as well.
With the rise of the Microsoft Windows platform in the 1990s, and the flexible macros of its applications, it became possible to write infectious code in the macro language of Microsoft Word and similar programs. These macro viruses infect documents and templates rather than applications (executables), but rely on the fact that macros in a Word document are a form of executable code.
The notion of a self-reproducing computer program can be traced back to initial theories about the operation of complex automata. John von Neumann showed that in theory a program could reproduce itself. This constituted a plausibility result in computability theory. Fred Cohen experimented with computer viruses and confirmed Neumann's postulate and investigated other properties of malware such as detectability and self-obfuscation using rudimentary encryption. His 1987 doctoral dissertation was on the subject of computer viruses. The combination of cryptographic technology as part of the payload of the virus, exploiting it for attack purposes was initialized and investigated from the mid 1990s, and includes initial ransomware and evasion ideas.
- Browser hijacking
- Comparison of antivirus software
- Computer security
- Cyber spying
- Domain generation algorithm
- Facebook malware
- File binder
- Identity theft
- Industrial espionage
- Linux malware
- Security in Web apps
- Social engineering (security)
- Targeted threat
- Telemetry software
- Web server overload causes
- Zombie (computer science)
- "Defining Malware: FAQ". technet.microsoft.com. Retrieved 10 September 2009.
- "An Undirected Attack Against Critical Infrastructure" (PDF). United States Computer Emergency Readiness Team(Us-cert.gov). Retrieved 28 September 2014.
- Russinovich, Mark (31 October 2005). "Sony, Rootkits and Digital Rights Management Gone Too Far". Mark's Blog. Microsoft MSDN. Retrieved 29 July 2009.
- "Protect Your Computer from Malware". OnGuardOnline.gov. 11 October 2012. Retrieved 26 August 2013.
- "Malware". FEDERAL TRADE COMMISSION- CONSUMER INFORMATION. Retrieved 27 March 2014.
- Hernandez, Pedro. "Microsoft Vows to Combat Government Cyber-Spying". eWeek. Retrieved 15 December 2013.
- Kovacs, Eduard. "MiniDuke Malware Used Against European Government Organizations". Softpedia. Retrieved 27 February 2013.
- "Malware Revolution: A Change in Target". March 2007.
- "Child Porn: Malware's Ultimate Evil". November 2009.
- PC World – Zombie PCs: Silent, Growing Threat.
- "Peer To Peer Information". NORTH CAROLINA STATE UNIVERSITY. Retrieved 25 March 2011.
- Richardson, Ronny; North, Max (1 January 2017). "Ransomware: Evolution, Mitigation and Prevention". International Management Review. 13 (1): 10–21.
- Fruhlinger, Josh (1 August 2017). "The 5 biggest ransomware attacks of the last 5 years". CSO. Retrieved 23 March 2018.
- "Another way Microsoft is disrupting the malware ecosystem". Retrieved 18 February 2015.
- "Shamoon is latest malware to target energy sector". Retrieved 18 February 2015.
- "Computer-killing malware used in Sony attack a wake-up call". Retrieved 18 February 2015.
- "computer virus – Encyclopædia Britannica". Britannica.com. Retrieved 28 April 2013.
- "All about Malware and Information Privacy - TechAcute". techacute.com. 31 August 2014.
- "What are viruses, worms, and Trojan horses?". Indiana University. The Trustees of Indiana University. Retrieved 23 February 2015.
- Peter Szor (3 February 2005). The Art of Computer Virus Research and Defense. Pearson Education. p. 204. ISBN 978-0-672-33390-3.
- "Rise of Android Ransomware, research" (PDF). ESET.
- "State of Malware, research" (PDF). Malwarebytes.
- Landwehr, C. E; A. R Bull; J. P McDermott; W. S Choi (1993). A taxonomy of computer program security flaws, with examples. DTIC Document. Retrieved 5 April 2012.
- "Trojan Horse Definition". Retrieved 5 April 2012.
- "Trojan horse". Webopedia. Retrieved 5 April 2012.
- "What is Trojan horse? – Definition from Whatis.com". Retrieved 5 April 2012.
- "Trojan Horse: [coined By MIT-hacker-turned-NSA-spook Dan Edwards] N." Retrieved 5 April 2012.
- "What is the difference between viruses, worms, and Trojan horses?". Symantec Corporation. Retrieved 10 January 2009.
- "VIRUS-L/comp.virus Frequently Asked Questions (FAQ) v2.00 (Question B3: What is a Trojan Horse?)". 9 October 1995. Retrieved 13 September 2012.
- "Proton Mac Trojan Has Apple Code Signing Signatures Sold to Customers for $50k". AppleInsider.
- "Non-Windows Malware". Betanews.
- McDowell, Mindi. "Understanding Hidden Threats: Rootkits and Botnets". US-CERT. Retrieved 6 February 2013.
- "Catb.org". Catb.org. Retrieved 15 April 2010.
- Vincentas (11 July 2013). "Malware in SpyWareLoop.com". Spyware Loop. Retrieved 28 July 2013.
- Staff, SPIEGEL (29 December 2013). "Inside TAO: Documents Reveal Top NSA Hacking Unit". Spiegel Online. SPIEGEL. Retrieved 23 January 2014.
- Edwards, John. "Top Zombie, Trojan Horse and Bot Threats". IT Security. Retrieved 25 September 2007.
- Appelbaum, Jacob (29 December 2013). "Shopping for Spy Gear:Catalog Advertises NSA Toolbox". Spiegel Online. SPIEGEL. Retrieved 29 December 2013.
- "Evasive malware goes mainstream - Help Net Security". net-security.org. 22 April 2015.
- Kirat, Dhilung; Vigna, Giovanni; Kruegel, Christopher (2014). Barecloud: bare-metal analysis-based evasive malware detection. ACM. pp. 287–301. ISBN 978-1-931971-15-7.
Freely accessible at: "Barecloud: bare-metal analysis-based evasive malware detection" (PDF).
- The Four Most Common Evasive Techniques Used by Malware. 27 April 2015.
- Young, Adam; Yung, Moti (1997). "Deniable Password Snatching: On the Possibility of Evasive Electronic Espionage". Symp. on Security and Privacy. IEEE. pp. 224–235. ISBN 0-8186-7828-3.
- Casey, Henry T. (25 November 2015). "Latest adware disables antivirus software". Tom's Guide. Yahoo.com. Retrieved 25 November 2015.
- Cabaj, Krzysztof; Caviglione, Luca; Mazurczyk, Wojciech; Wendzel, Steffen; Woodward, Alan; Zander, Sebastian (May 2018). "The New Threats of Information Hiding: The Road Ahead". IT Professional. 20 (3): 31–39. arXiv:1801.00694. doi:10.1109/MITP.2018.032501746.
- "Global Web Browser... Security Trends" (PDF). Kaspersky lab. November 2012.
- Rashid, Fahmida Y. (27 November 2012). "Updated Browsers Still Vulnerable to Attack if Plugins Are Outdated". pcmag.com.
- Danchev, Dancho (18 August 2011). "Kaspersky: 12 different vulnerabilities detected on every PC". pcmag.com.
- "Adobe Security bulletins and advisories". Adobe.com. Retrieved 19 January 2013.
- Rubenking, Neil J. "Secunia Personal Software Inspector 3.0 Review & Rating". PCMag.com. Retrieved 19 January 2013.
- "USB devices spreading viruses". CNET. CBS Interactive. Retrieved 18 February 2015.
- "LNCS 3786 – Key Factors Influencing Worm Infection", U. Kanlayasiri, 2006, web (PDF): SL40-PDF.
- "How Antivirus Software Works?". Retrieved 16 October 2015.
- "Microsoft Security Essentials". Microsoft. Retrieved 21 June 2012.
- "Malicious Software Removal Tool". Microsoft. Archived from the original on 21 June 2012. Retrieved 21 June 2012.
- "Windows Defender". Microsoft. Archived from the original on 22 June 2012. Retrieved 21 June 2012.
- Rubenking, Neil J. (8 January 2014). "The Best Free Antivirus for 2014". pcmag.com.
- "Free antivirus profiles in 2018". antivirusgratis.org. Archived from the original on 10 August 2018.
- "Quickly identify malware running on your PC". techadvisor.co.uk.
- "How do I remove a computer virus?". Microsoft. Retrieved 26 August 2013.
- "Microsoft Safety Scanner". Microsoft. Retrieved 26 August 2013.
- "An example of a website vulnerability scanner". Unmaskparasites.com. Retrieved 19 January 2013.
- "Redleg's File Viewer. Used to check a webpage for malicious redirects or malicious HTML coding". Aw-snap.info. Retrieved 19 January 2013.
- "Example Google.com Safe Browsing Diagnostic page". Retrieved 19 January 2013.
- "Safe Browsing (Google Online Security Blog)". Retrieved 21 June 2012.
- M. Guri, G. Kedma, A. Kachlon and Y. Elovici, "AirHopper: Bridging the air-gap between isolated networks and mobile phones using radio frequencies," Malicious and Unwanted Software: The Americas (MALWARE), 2014 9th International Conference on, Fajardo, PR, 2014, pp. 58-67.
- M. Guri, M. Monitz, Y. Mirski and Y. Elovici, "BitWhisper: Covert Signaling Channel between Air-Gapped Computers Using Thermal Manipulations," 2015 IEEE 28th Computer Security Foundations Symposium, Verona, 2015, pp. 276-289.
- GSMem: Data Exfiltration from Air-Gapped Computers over GSM Frequencies. Mordechai Guri, Assaf Kachlon, Ofer Hasson, Gabi Kedma, Yisroel Mirsky, and Yuval Elovici, Ben-Gurion University of the Negev; USENIX Security Symposium 2015
- Hanspach, Michael; Goetz, Michael; Daidakulov, Andrey; Elovici, Yuval (2016). "Fansmitter: Acoustic Data Exfiltration from (Speakerless) Air-Gapped Computers". arXiv:1606.05915 [cs.CR].
- Vincentas (11 July 2013). "Grayware in SpyWareLoop.com". Spyware Loop. Archived from the original on 15 July 2014. Retrieved 28 July 2013.
- "Threat Encyclopedia – Generic Grayware". Trend Micro. Retrieved 27 November 2012.
- "Rating the best anti-malware solutions". Arstechnica. 15 December 2009. Retrieved 28 January 2014.
- "PUP Criteria". malwarebytes.org. Retrieved 13 February 2015.
- "Boot sector virus repair". Antivirus.about.com. 10 June 2010. Archived from the original on 12 January 2011. Retrieved 27 August 2010.
- Avoine, Gildas; Pascal Junod; Philippe Oechslin (2007). Computer system security: basic concepts and solved exercises. EFPL Press. p. 20. ISBN 978-1-4200-4620-5.
The first PC virus is credited to two brothers, Basit Farooq Alvi and Amjad Farooq Alvi, from Pakistan
- William A Hendric (4 September 2014). "Computer Virus history". The Register. Retrieved 29 March 2015.
- "Cryptomining Worm MassMiner Exploits Multiple Vulnerabilities - Security Boulevard". Security Boulevard. 2 May 2018. Retrieved 9 May 2018.
- "Malware: Types, Protection, Prevention, Detection & Removal - Ultimate Guide". EasyTechGuides.
- "Beware of Word Document Viruses". us.norton.com. Retrieved 25 September 2017.
- John von Neumann, "Theory of Self-Reproducing Automata", Part 1: Transcripts of lectures given at the University of Illinois, December 1949, Editor: A. W. Burks, University of Illinois, USA, 1966.
- Fred Cohen, "Computer Viruses", PhD Thesis, University of Southern California, ASP Press, 1988.
- Young, Adam; Yung, Moti (2004). Malicious cryptography - exposing cryptovirology. Wiley. pp. 1–392. ISBN 978-0-7645-4975-5.
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