Anatomy of the Virus

Warning: This is a LONG article.

Before we get into the meat of this thing, let me begin by saying that Viruses, Trojans, Spyware, Malware, Adware, etc. are bad things that can happen to your computer. Think of them as your computer getting sick. Like other sicknesses, sometimes these computer sicknesses can spread to other computers (that's why they call 'em viruses). If your computer gets sick, it is only right and responsible to get it cured before you go and infect everyone you know, and possibly hundreds of thousands of people you do not know.

Also, like other sicknesses, you can avoid them with due diligence. Avoid sites where pirated material is distributed. Avoid downloading pirated or copyrighted material. Avoid sites with dark or illegal content. Avoid downloading dark or illegal content. Keep your computer(s) well-inoculated with Antivirus and Anti-malware (click here if you can't afford this).

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The following definitions (Computer Virus, Trojan Horse, and Worm) were taken without shame from Wikipedia (www.wikipedia.com) for your edification; links therein will take you to other Wikipedia definitions. Wikipedia is an excellent source for information but should NEVER be used without verification from other sources, as anyone can upload data to Wikipedia and there it will stay unless repudiated by alternative sources. Articles and sources copied here are protected by the GNU Free Documentation License, and GCITS has made efforts to comply with this license. Please contact us if you notice some breach of this License Agreement; we'd rather be the first to know than the last. Additionally, if you would like to see the following information in its original form, please visit here, here, and here.

GCITS recommends Panda Antivirus 2007 for protection from Viruses, Trojans, and Worms. Come by today to pick up a license and have it installed.

Computer virus

From Wikipedia, the free encyclopedia

A computer virus is a computer program that can copy itself and infect a computer without permission or knowledge of the user. The original may modify the copies or the copies may modify themselves, as occurs in a metamorphic virus. A virus can only spread from one computer to another when its host is taken to the uninfected computer, for instance by a user sending it over a network or carrying it on a removable medium such as a floppy disk, CD, USB drive or by the Internet. Additionally, viruses can spread to other computers by infecting files on a network file system or a file system that is accessed by another computer. Viruses are sometimes confused with computer worms and Trojan horses. A worm, however, can spread itself to other computers without needing to be transferred as part of a host. A Trojan horse is a file that appears harmless until executed. In contrast to viruses, Trojan horses do not insert their code into other computer files. Many personal computers are now connected to the Internet and to local-area networks, facilitating their spread. Today's viruses may also take advantage of network services such as the World Wide Web, e-mail, and file sharing systems to spread, blurring the line between viruses and worms. Furthermore, some sources use an alternative terminology in which a virus is any form of self-replicating malware.

The term comes from the term virus in biology. A computer virus reproduces by making (possibly modified) copies of itself in the computer's memory, storage, or over a network. This is similar to the way a biological virus works.

Some viruses are programmed to damage the computer by damaging programs, deleting files, or reformatting the hard disk. Others are not designed to do any damage, but simply replicate themselves and perhaps make their presence known by presenting text, video, or audio messages. Even these benign viruses can create problems for the computer user. They typically take up computer memory used by legitimate programs. As a result, they often cause erratic behavior and can result in system crashes. In addition, many viruses are bug-ridden, and these bugs may lead to system crashes and data loss.

There are many viruses operating in the general Internet today, and new ones are created and discovered every day.

Trojan horse (computing)

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This article is about computer system security. For Odysseus's subterfuge in the Trojan War, see Trojan Horse.

In the context of computer software, a Trojan horse is a program that installs malicious software while under the guise of doing something else. A Trojan horse differs from a virus in that a Trojan horse does not insert its code into other computer files and appears harmless until executed. The term is derived from the classical myth of the Trojan Horse. Trojan horses may appear to be useful or interesting programs (or at the very least harmless) to an unsuspecting user, but are actually harmful when executed. (See Social engineering.)

There are two common types of Trojan horses. One is ordinary software that has been corrupted by a hacker. A hacker inserts malicious code into the program that executes while the program is used. Examples include various implementations of weather alerting programs, computer clock setting software, and peer-to-peer file sharing utilities. The other type of Trojan is a standalone program that masquerades as something else, like a game or image file, in order to trick the user into running the program.

Trojan horse programs cannot operate autonomously, in contrast to some other types of malware, like viruses or worms. Just as the Greeks needed the Trojans to bring the horse inside for their plan to work, Trojan horse programs depend on actions by the intended victims. As such, if Trojans replicate and distribute themselves, each new victim must run the Trojan. Therefore their virulence is of a different nature, depending on successful implementation of social engineering concepts rather than flaws in a computer system's security design or configuration.

In the field of computer architecture, 'Trojan Horse' can also refer to security loopholes that allow Kernel Code to access anything for which it is not authorized.

Computer worm

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A computer worm is a self-replicating computer program. It uses a network to send copies of itself to other nodes (computer terminals on the network) and it may do so without any user intervention. Unlike a virus, it does not need to attach itself to an existing program. Worms always harm the network (if only by consuming bandwidth), whereas viruses always infect or corrupt files on a targeted computer.

[edit] Naming and history

The name worm comes from The Shockwave Rider, a science fiction novel published in 1975 by John Brunner. Researchers John F Shoch and Jon A Hupp of Xerox PARC chose the name in a paper published in 1982; The Worm Programs, Comm ACM, 25(3):172-180, 1982), and it has since been widely adopted.

The first implementation of a worm was by these same two researchers at Xerox PARC in 1978.^[1] Shoch and Hupp originally designed the worm to find idle processors on the network and assign them tasks, sharing the processing load, and so improving the 'CPU cycle use efficiency' across an entire network. They were self-limited so that they would spread no farther than intended.^[2]

[edit] Payloads

Many worms have been created which are only designed to spread, and don't attempt to alter the systems they pass through. However, as the Morris worm, and Mydoom showed, the network traffic and other unintended effects can often cause major disruption. A "payload" is code designed to do more than spread the worm - it might delete files on a host system (eg the ExploreZip worm), encrypt files in a cryptoviral extortion attack, or send documents via e-mail. A very common payload for worms is to install a backdoor in the infected computer to allow the creation of a "zombie" under control of the worm author - Sobig and Mydoom are examples which created zombies. Networks of such machines are often referred to as botnets and are very commonly used by spam senders for sending junk email or to cloak their website's address.^[3] Spammers are therefore thought to be a source of funding for the creation of such worms,^[4][5] and worm writers have been caught selling lists of IP addresses of infected machines.^[6] Others try to blackmail companies with threatened DoS attacks.^[7]]

Backdoors, however they may be installed, can be exploited by other malware, including worms. Examples include Doomjuice, which spreads using the backdoor opened by Mydoom, and at least one instance of malware taking advantage of the rootkit backdoor installed by the Sony/BMG DRM software utilized by millions of music CDs prior to late 2005.

[edit] Worms with good intent

Beginning with the very first research into worms at Xerox PARC there have been attempts to create useful worms. The Nachi family of worms, for example, tried to download and install patches from Microsoft's website to fix vulnerabilities in the host system — by exploiting those same vulnerabilities. In practice, although this may have made these systems more secure, it generated considerable network traffic, rebooted the machine in the course of patching it, and, most importantly, did its work without the consent of the computer's owner or user.

Most security experts regard all worms as malware, whatever their payload or their writers' intentions.

[edit] Protecting against dangerous computer worms

Worms mainly spread by exploiting vulnerabilities in operating systems, or by tricking users to assist them.

All vendors supply regular security updates^[8] (see "Patch Tuesday"), and if these are installed to a machine then the majority of worms are unable to spread to it. If a vendor acknowledges a vulnerability but has yet to release a security update to patch it, a zero day exploit is possible. However, these are relatively rare.

Users need to be wary of opening unexpected email, and should not run attached files or programs, or visit web sites that are linked to such emails. However, as the ILOVEYOU worm showed, and as phishing attacks become more efficient, tricking users will always be possible.

Anti-virus and anti-spyware software are helpful, but must be kept up-to-date with new pattern files at least every few days.

[edit] Mitigation techniques

• TCP Wrapper/libwrap enabled network service daemons
• ACLs in routers and switches
• Packet-filters
• Nullrouting

[edit] See also

• Timeline of notable computer viruses and worms
• Spam
• Spy software

[edit] References

1. ^ http://www.parc.xerox.com/about/history/default.html
2. ^ Computer Worm (Tapeworm) - The first description of a set of computer codes that moves from one computer to another on a network as a coherent entity.
3. ^ see seattle times ^ http://www.wired.com/news/business/0,1367,60747,00.html
4. ^ http://www.channelnewsasia.com/stories/afp_world/view/68810/1/.html
5. ^ http://www.heise.de/english/newsticker/news/44879
6. ^ http://news.bbc.co.uk/1/hi/technology/3513849.stm
7. ^ [1]

 [edit] External links

• The Wildlist - List of viruses and worms 'in the wild' (i.e. regularly encountered by anti-virus companies)
• Worm parasites - Listed worm descriptions and removal tools.
• Jose Nazario discusses worms - Worms overview by a famous security researcher.
• Computer worm suspect in court
• Vernalex.com's Malware Removal Guide - Guide for understanding, removing and preventing worm infections
• John Shoch, Jon Hupp "The "Worm" Programs - Early Experience with a Distributed Computation"
• RFC 1135 The Helminthiasis of the Internet
• Surfing Safe - A site providing tips/advice on preventing and removing viruses.
• Computer Worms Information
• The Case for Using Layered Defenses to Stop Worms David Albanese, Michael Wiacek, Christopher Salter, Jeffrey Six 2004

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