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 behaviour will continue. Computer worms use recursive methods to copy themselves without host programs and distribute themselves based on exploiting the advantages 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.
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.
The Melissa virus is a mass-mailing macro virus released on or around March 26, 1999. It targets Microsoft Word and Outlook-based systems and created considerable network traffic. The virus infects computers via email; the email is titled "Important Message From," followed by the current username. Upon clicking the message, the body reads, "Here's that document you asked for. Don't show anyone else ;)." Attached is a Word document titled "list.doc," containing a list of pornographic sites and accompanying logins for each. It then mass-mails itself to the first fifty people in the user's contact list and disables multiple safeguard features on Microsoft Word and Microsoft Outlook.
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. The virus was created by Chen Ing-hau, a student at Tatung University in Taiwan. It was believed to have infected sixty million computers internationally, resulting in an estimated NT$1 billion (US$35,801,231.56) in commercial damages.
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.
mydoom also known as, my.doom, W32.MyDoom@mm, Novarg, Mimail.R, Shimgapi, W32/Mydoom@MM, WORM_MYDOOM, Win32.Mydoom is a computer worm affecting Microsoft Windows. It was first sighted on January 26, 2004. It became the fastest-spreading e-mail worm ever, exceeding previous records set by the Sobig worm and ILOVEYOU, a record which as of 2023 has yet to be surpassed.
Elk Cloner is one of the first known microcomputer viruses that spread "in the wild", i.e., outside the computer system or laboratory in which it was written. It attached itself to the Apple II operating system and spread by floppy disk. It was written around 1982 by programmer and entrepreneur Rich Skrenta as a 15-year-old high school student, originally as a joke, and put it onto a game disk.
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.
Abraxas, also known as Abraxas5, discovered in April 1993, is an encrypted, overwriting, file infecting computer virus which infects .COM and .EXE files, although it does not infect command.com. It does not become memory resident. Each time an infected file is executed, Abraxas infects the copy of dosshell.com located in the C:\DOS directory, as well as one EXE file in the current directory. Due to a bug in the virus, only the first EXE file in any directory is infected.
AIDS is a DOS computer virus which overwrites COM files.
The Michelangelo virus is a computer virus first discovered on 4 February 1991 in Australia. The virus was designed to infect DOS systems, but did not engage the operating system or make any OS calls. Michelangelo, like all boot sector viruses, operated at the BIOS level. Each year, the virus remained dormant until March 6, the birthday of Renaissance artist Michelangelo. There is no reference to the artist in the virus, and it is doubtful that the virus's developer(s) intended a connection between the virus and the artist. The name was chosen by researchers who noticed the coincidence of the activation date. The actual significance of the date to the author is unknown. Michelangelo is a variant of the already endemic Stoned virus.
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.
The Nimda virus is a malicious file-infecting computer worm. It quickly spread, surpassing the economic damage caused by previous outbreaks such as Code Red.
Alabama is a computer virus, discovered in October 1989 on the campus of the Hebrew University of Jerusalem.
OneHalf is a DOS-based polymorphic computer virus discovered in October 1994. It is also known as Slovak Bomber, Freelove or Explosion-II. It infects the master boot record (MBR) of the hard disk, and any files with extensions .COM, .SCR and .EXE. However, it will not infect files that have SCAN, CLEAN, FINDVIRU, GUARD, NOD, VSAFE, MSAV or CHKDSK in the name.
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.
W32.Navidad is a mass-mailing worm program or virus, discovered in December 2000 that ran on Windows 95, Windows 98, Windows NT, and Windows 2000 systems. It was designed to spread through email clients such as Microsoft Outlook while masquerading as an executable electronic Christmas card. Infected computers can be identified by blue eye icons which appear in the Windows system tray.
A computer virus is a type of malware that, when executed, replicates itself by modifying other computer programs and inserting its own code into those programs. If this replication succeeds, the affected areas are then said to be "infected" with a computer virus, a metaphor derived from biological viruses.
Gumblar is a malicious JavaScript trojan horse file that redirects a user's Google searches, and then installs rogue security software. Also known as Troj/JSRedir-R this botnet first appeared in 2009.
