Source code viruses are a subset of computer viruses that make modifications to source code located on an infected machine. A source file can be overwritten such that it includes a call to some malicious code. By targeting a generic programming language, such as C, source code viruses can be very portable. Source code viruses are rare, partly due to the difficulty of parsing source code programmatically, but have been reported to exist.
One such virus (W32/Induc-A) was identified by anti-virus specialist Sophos as capable of injecting itself into the source code of any Delphi program it finds on an infected computer, and then compiles itself into a finished executable. [1]
A computer worm is a standalone malware computer program that replicates itself in order to spread to other computers. It often uses a computer network to spread itself, relying on security failures on the target computer to access it. It will use this machine as a host to scan and infect other computers. When these new worm-invaded computers are controlled, the worm will continue to scan and infect other computers using these computers as hosts, and this behavior will continue. Computer worms use recursive methods to copy themselves without host programs and distribute themselves based on the law of exponential growth, thus controlling and infecting more and more computers in a short time. Worms almost always cause at least some harm to the network, even if only by consuming bandwidth, whereas viruses almost always corrupt or modify files on a targeted computer.
Malware is any software intentionally designed to cause disruption to a computer, server, client, or computer network, leak private information, gain unauthorized access to information or systems, deprive users access to information or which unknowingly interferes with the user's computer security and privacy. By contrast, software that causes harm due to some deficiency is typically described as a software bug. Malware poses serious problems to individuals and businesses on the Internet. According to Symantec’s 2018 Internet Security Threat Report (ISTR), malware variants number has increased to 669,947,865 in 2017, which is twice as many malware variants as in 2016. Cybercrime, which includes malware attacks as well as other crimes committed by computer, was predicted to cost the world economy 6 trillion dollars in 2021, and is increasing at a rate of 15% per year.
In computing terminology, a macro virus is a virus that is written in a macro language: a programming language which is embedded inside a software application. Some applications, such as Microsoft Office, Excel, PowerPoint allow macro programs to be embedded in documents such that the macros are run automatically when the document is opened, and this provides a distinct mechanism by which malicious computer instructions can spread. This is one reason it can be dangerous to open unexpected attachments in e-mails. Many antivirus programs can detect macro viruses; however, the macro virus' behavior can still be difficult to detect.
Pascal is an imperative and procedural programming language, designed by Niklaus Wirth as a small, efficient language intended to encourage good programming practices using structured programming and data structuring. It is named in honour of the French mathematician, philosopher and physicist Blaise Pascal.
This timeline of computer viruses and worms presents a chronological timeline of noteworthy computer viruses, computer worms, Trojan horses, similar malware, related research and events.
Antivirus software, or antivirus software, also known as anti-malware, is a computer program used to prevent, detect, and remove malware.
CIH, also known as Chernobyl or Spacefiller, is a Microsoft Windows 9x computer virus that first emerged in 1998. Its payload is highly destructive to vulnerable systems, overwriting critical information on infected system drives and, in some cases, destroying the system BIOS. Chen Ing-hau, a student at Tatung University in Taiwan, created the virus. It was believed to have infected sixty million computers internationally, resulting in an estimated US$1 billion in commercial damages.
A backdoor is a typically covert method of bypassing normal authentication or encryption in a computer, product, embedded device, or its embodiment. Backdoors are most often used for securing remote access to a computer, or obtaining access to plaintext in cryptographic systems. From there it may be used to gain access to privileged information like passwords, corrupt or delete data on hard drives, or transfer information within autoschediastic networks.
Linux malware includes viruses, Trojans, worms and other types of malware that affect the Linux family of operating systems. Linux, Unix and other Unix-like computer operating systems are generally regarded as very well-protected against, but not immune to, computer viruses.
Bagle was a mass-mailing computer worm affecting Microsoft Windows. The first strain, Bagle.A, did not propagate widely. A second variant, Bagle.B, was considerably more virulent.
Metamorphic code is code that when run outputs a logically equivalent version of its own code under some interpretation. This is similar to a quine, except that a quine's source code is exactly equivalent to its own output. Metamorphic code also usually outputs machine code and not its own source code.
AIDS is a computer virus written in Turbo Pascal 3.01a which overwrites COM files. AIDS is the first virus known to exploit the MS-DOS "corresponding file" vulnerability. In MS-DOS, if both foo.com and foo.exe exist, then foo.com will always be executed first. Thus, by creating infected com files, AIDS code will always be executed before the intended exe code.
Win32/Simile is a metamorphic computer virus written in assembly language for Microsoft Windows. The virus was released in its most recent version in early March 2002. It was written by the virus writer "Mental Driller". Some of his previous viruses, such as Win95/Drill, have proved very challenging to detect.
Mobile malware is malicious software that targets mobile phones or wireless-enabled Personal digital assistants (PDA), by causing the collapse of the system and loss or leakage of confidential information. As wireless phones and PDA networks have become more and more common and have grown in complexity, it has become increasingly difficult to ensure their safety and security against electronic attacks in the form of viruses or other malware.
Jerusalem is a logic bomb DOS virus first detected at Hebrew University of Jerusalem, in October 1987. On infection, the Jerusalem virus becomes memory resident, and then infects every executable file run, except for COMMAND.COM. COM files grow by 1,813 bytes when infected by Jerusalem and are not re-infected. Executable files grow by 1,808 to 1,823 bytes each time they are infected, and are then re-infected each time the files are loaded until they are too large to load into memory. Some .EXE files are infected but do not grow because several overlays follow the genuine .EXE file in the same file. Sometimes .EXE files are incorrectly infected, causing the program to fail to run as soon as it is executed.
Beast is a Windows-based backdoor trojan horse, more commonly known in the hacking community as a Remote Administration Tool or a "RAT". It is capable of infecting versions of Windows from 95 to XP. Written in Delphi and released first by its author Tataye in 2002, it became quite popular due to its unique features. It used the typical client–server model where the client would be under operation by the attacker and the server is what would infect the victim. Beast was one of the first trojans to feature a reverse connection to its victims, and once established it gave the attacker complete control over the infected computer. The virus would be harmless until opened. When opened, the virus would use the code injection method to inject itself into other applications.
Stoned is a boot sector computer virus created in 1987. It is one of the first viruses and is thought to have been written by a student in Wellington, New Zealand. By 1989 it had spread widely in New Zealand and Australia, and variants became very common worldwide in the early 1990s.
Shankar's Virus is a polymorphic computer virus that infects Microsoft Word documents and templates. It was discovered on 3 June 1999.
A computer virus is a type of computer program that, when executed, replicates itself by modifying other computer programs and inserting its own code. If this replication succeeds, the affected areas are then said to be "infected" with a computer virus, a metaphor derived from biological viruses.
A compression virus is an example of a benevolent computer virus, invented by Fred Cohen. It searches for an uninfected executable file, compresses the file and prepends itself to it. The virus can be described in pseudo code
program compression-virus:= {01234567; subroutine infect-executable:= {loop:file = get-random-executable-file; if first-line-of-file = 01234567 then goto loop; compress file; prepend compression-virus to file; } main-program:= {if ask-permission then infect-executable; uncompress the-rest-of-this-file into tmpfile; run tmpfile;} }