Spyware is computer software that collects personal information about a user without their informed consent. The term, coined in 1995 but not widely used for another five years, is often used interchangeably with adware and malware (software designed to infiltrate and damage a computer).
Personal information is secretly recorded with a variety of techniques, including logging keystrokes, recording Internet web browsing history, and scanning documents on the computer's hard disk. Purposes range from overtly criminal (theft of passwords and financial details) to the merely annoying (recording Internet search history for targeted advertising, while consuming computer resources). Spyware collects many different types of information. Some variants attempt to track the websites a user visits and then send this information to an advertising agency. More malicious variants attempt to intercept passwords or credit card numbers as a user enters them into a web form or other application.
The spread of spyware has led to the development of an entire anti-spyware industry. Its products remove or disable existing spyware on the computers they are installed on and prevent its installation. However, a number of companies have incorporated forms of spyware into their products. These programs are not considered malware, but are still spyware as they watch and observe with for advertising purposes. It is debatable whether such 'legitimate' uses of adware/spyware are malware since the user often has no knowledge of these 'legitimate' programs being installed on his/her computer and is generally unaware that these programs are infringing on his/her privacy. In any case, these programs still use the resources of the host computer without permission.
- 1 History and development
- 2 Comparison ------------>2.1 Spyware, adware and tracking
- 3 Routes of infection
- 4 Effects and behaviors ------------>4.1 Advertisements
- 5 Legal issues related to spyware ------------>5.1 Criminal law
- 6 Remedies and prevention ------------>6.1 Anti-spyware programs
- 7 Notable programs distributed with spyware ------------>7.1 Notable programs formerly distributed with spyware
- 8 References
------------>2.2 Spyware, virus and worm
------------>4.2 "Stealware" and affiliate fraud
------------>4.3 Identity theft and fraud
------------>4.4 Digital rights management
------------>4.5 Spyware and cookies
------------>4.6 Examples of spyware
------------>5.2 Civil law
------------>5.3 Libel suits by spyware developers
------------>6.2 Fake anti-spyware programs
------------>6.3 Security practices
History and development
The first recorded use of the term spyware occurred on October 16, 1995 in a Usenet post that poked fun at Microsoft's business model. Spyware at first denoted hardware meant for espionage purposes. However, in early 2000 the founder of Zone Labs, Gregor Freund, used the term in a press release for the ZoneAlarm Personal Firewall. Since then, "spyware" has taken on its present sense.
In early 2001, Steve Gibson of Gibson Research realized that advertising software had been installed on his system, and suspected it was stealing his personal information. After analysis, he determined that it was adware from the companies Aureate (later Radiate) and Conducent. Gibson developed and released the first anti-spyware program, OptOut. Many more have appeared since then.
According to a November 2004 study by AOL and the National Cyber-Security Alliance, 80% of surveyed users' computers had some form of spyware, with an average of 93 spyware components per computer (such counts usually include 'cookies' which report back to a website, but are not software as such). 89% of surveyed users with spyware reported that they did not know of its presence, and 95% reported that they had not given permission for the installation of the spyware.
As of 2006, spyware has become one of the preeminent security threats to computer systems running Microsoft Windows operating systems. In an estimate based on customer-sent scan logs, Webroot Software, makers of Spy Sweeper, said that 9 out of 10 computers connected to the Internet are infected. Computers where Internet Explorer (IE) is the primary browser are particularly vulnerable to such attacks not only because IE is the most widely-used but because its tight integration with Windows allows spyware acccess to crucial parts of the operating system.
Spyware, adware and tracking
The term adware frequently refers to any software which displays advertisements, whether or not the user has consented. Programs such as the Eudora mail client display advertisements as an alternative to shareware registration fees. These classify as "adware" in the sense of advertising-supported software, but not as spyware. Adware in this form does not operate surreptitiously or mislead the user, and provides the user with a specific service.
Most spyware is adware in a different sense: it displays advertising. Claria Corporation's Gator Software and Exact Advertising's BargainBuddy are examples. Visited Web sites frequently install Gator on client machines in a surreptitious manner, and it directs revenue to the installing site and to Claria by displaying advertisements to the user. The user receives many pop-up advertisements.
Other spyware behavior, such as reporting on websites the user visits, occurs in the background. The data is used for "targeted" advertisement impressions. The prevalence of spyware has cast suspicion upon other programs that track Web browsing, even for statistical or research purposes. Some observers describe the Alexa Toolbar, an Internet Explorer plug-in published by Amazon.com, as spyware (and some anti-spyware programs report it as such). Many users, however, choose to install it.
Spyware, virus and worm
Unlike viruses and worms, spyware does not usually self-replicate. Like many recent viruses, however, spyware by design exploits infected computers for commercial gain. Typical tactics furthering this goal include delivery of unsolicited pop-up advertisements; theft of personal information (including financial information such as credit card numbers); monitoring of Web-browsing activity for marketing purposes; or routing of HTTP requests to advertising sites.
Routes of infection
Spyware does not directly spread in the manner of a computer virus or worm: generally, an infected system does not attempt to transmit the infection to other computers. Instead, spyware gets on a system through deception of the user or through exploitation of software vulnerabilities.
Most spyware is installed without users being aware. Since they tend not to install software if they know that it will disrupt their working environment and compromise their privacy, spyware deceives users, either by piggybacking on a piece of desirable software such as Kazaa, or tricking them into installing it (the Trojan horse method). Some "rogue" anti-spyware programs even masquerade as security software.
The distributor of spyware usually presents the program as a useful utility for instance as a "Web accelerator" or as a helpful software agent. Users download and install the software without immediately suspecting that it could cause harm. For example, Bonzi Buddy, a spyware program targeted at children, claims that:
He will explore the Internet with you as your very own friend and sidekick! He can talk, walk, joke, browse, search, e-mail, and download like no other friend you've ever had! He even has the ability to compare prices on the products you love and help you save money! Best of all, he's FREE!
Spyware can also come bundled with shareware or other downloadable software, as well as music CDs. The user downloads a progam and installs it, and the installer additionally installs the spyware. Although the desirable software itself may do no harm, the bundled spyware does. In some cases, spyware authors have paid shareware authors to bundle spyware with their software. In other cases, spyware authors have repackaged desirable free software with installers that add spyware.
A third way of distributing spyware involves tricking users by manipulating security features designed to prevent unwanted installations. IE prevents websites from initiating an unwanted download. Instead, it requires a user action, such as clicking on a link. However, links can prove deceptive: for instance, a pop-up ad may appear like a standard Windows dialog box. The box contains a message such as "Would you like to optimise your Internet access?" with links which look like buttons reading Yes and No. No matter which "button" the user presses, a download starts, placing the spyware on the user's system. Later versions of IE offer fewer avenues for this attack.
Some spyware authors infect a system through security holes in the Web browser or in other software. When the user navigates to a Web page controlled by the spyware author, the page contains code which attacks the browser and forces the download and installation of spyware. The spyware author would also have some extensive knowledge of commercially-available anti-virus and firewall software. This has become known as a "drive-by download", which leaves the user a hapless bystander to the attack. Common browser exploits target security vulnerabilities in Internet Explorer and in the Microsoft Java runtime.
The installation of spyware frequently involves Internet Explorer. Its popularity and history of security issues have made it the most frequent target. Its deep integration with the Windows environment and scriptability make it an obvious point of attack into Windows. Internet Explorer also serves as a point of attachment for spyware in the form of Browser Helper Objects, which modify the browser's behaviour to add toolbars or to redirect traffic.
In a few cases, a worm or virus has delivered a spyware payload. Some attackers used the Spybot worm to install spyware that put pornographic pop-ups on the infected system's screen. By directing traffic to ads set up to channel funds to the spyware authors, they can profit even from such clearly illegal behaviour.
Effects and behaviors
A spyware program is rarely alone on a computer: an affected machine can rapidly be infected by many other components. Users frequently notice unwanted behavior and degradation of system performance. A spyware infestation can create significant unwanted CPU activity, disk usage, and network traffic, all of which slow the computer down. Stability issues, such as application or system-wide crashes, are also common. Spyware which interferes with networking software commonly causes difficulty connecting to the Internet.
In some infections, the spyware is not even evident. Users assume in those situations that the issues relate to hardware, to Windows installation problems, or a virus. Some owners of badly infected systems resort to contacting technical support experts, or even buying a new computer because the existing system "has become too slow". Badly infected systems may require a clean reinstall of all their software in order to return to full functionality.
Only rarely does a single piece of software render a computer unusable. Rather, a computer will likely have multiple infections. As the 2004 AOL study noted, if a computer has any spyware at all, it typically has dozens of different pieces installed. The cumulative effect, and the interactions between spyware components, cause the symptoms commonly reported by users: a computer which slows to a crawl, overwhelmed by the many parasitic processes running on it. Moreover, some types of spyware disable software firewalls and anti-virus software, and/or reduce browser security settings, thus opening the system to further opportunistic infections, much like an immune deficiency disease. Documented cases have also occurred where a spyware program has disabled other spyware programs that have been installed by its competitors.
Some other types of spyware (Targetsoft, for example) modify system files so they will be harder to remove. Targetsoft modifies the "Winsock" Windows Sockets files. The deletion of the spyware-infected file "inetadpt.dll" will interrupt normal networking usage. Unlike users of many other operating systems, a typical Windows user has administrative privileges, mostly for convenience. Because of this, any program the user runs (intentionally or not) has unrestricted access to the system. Spyware, along with other threats, has led some Windows users to move to other platforms such as Linux or Apple Macintosh, which are less attractive targets for malware. This is because these programs are not granted unrestricted access to the operating system (due to the Unix underpinnings upon which both Linux and Mac OS X are built) and some allege it's partly due to the far smaller number of machines installed with these operating systems making spyware development potentially less profitable for these platforms.
Many spyware programs display advertisements. Some programs simply display pop-up ads on a regular basis; for instance, one every several minutes, or one when the user opens a new browser window. Others display ads in response to specific sites that the user visits. Spyware operators present this feature as desirable to advertisers, who may buy ad placement in pop-ups displayed when the user visits a particular site. It is also one of the purposes for which spyware programs gather information on user behavior. Pop-ups are one of users' most common complaints about spyware.
Many users complain about irritating or offensive advertisements as well. As with many banner ads, many spyware advertisements use animation or flickering banners which can be visually distracting and annoying to users. Pop-up ads for pornography often display indiscriminately. When children are the users, this could possibly violate anti-pornography laws in some jurisdictions.
A further issue in the case of some spyware programs has to do with the replacement of banner ads on viewed web sites. Spyware that acts as a web proxy or a Browser Helper Object can replace references to a site's own advertisements (which fund the site) with advertisements that instead fund the spyware operator. This cuts into the margins of advertising-funded Web sites.
"Stealware" and affiliate fraud
A few spyware vendors, notably 180 Solutions, have written what the New York Times has dubbed "stealware", and what spyware-researcher Ben Edelman terms affiliate fraud, also known as click fraud. Stealware diverts the payment of affiliate marketing revenues from the legitimate affiliate to the spyware vendor.
Spyware which attacks affiliate networks places the spyware operator's affiliate tag on the user's activityreplacing any other tag, if there is one. The spyware operator is the only party that gains from this. The user has their choices thwarted, a legitimate affiliate loses revenue, Networks' reputations are injured, and vendors are harmed by having to pay out affiliate revenues to an "affiliate" who is not party to a contract.
Affiliate fraud is a violation of the terms of service of most affiliate marketing networks. As a result, spyware operators such as 180 Solutions have been terminated from affiliate networks including LinkShare and ShareSale.
Identity theft and fraud
In one case, spyware has been closely associated with identity theft. In August 2005, researchers from security software firm Sunbelt Software believed that the makers of the common CoolWebSearch spyware had used it to transmit "chat sessions, user names, passwords, bank information, etc.", but it turned out that "it actually (was) its own sophisticated criminal little trojan that's independent of CWS." This case is currently under investigation by the FBI.
That case aside, identity theft remains theoretically possible as keyloggers are routinely packaged with spyware. Information security researcher John Bambenek estimates that identity thieves have stolen over $24 billion US dollars of account information in the United States alone.
Spyware-makers may commit wire fraud with dialer program spyware. These can reset a modem to dial up a premium-rate telephone number instead of the usual ISP. Connecting to these suspicious numbers involves long-distance or overseas charges which invariably result in high charges. Dialers are ineffective on computers that do not have a modem, or are not connected to a telephone line.
Digital rights management
Some copy-protection technologies also use spyware techniques. Digital rights management technologies (such as Sony's XCP) actually use trojan-horse tactics to verify a user's lawful ownership of the file in question.Sony has been sued for using virus-like techniques to prevent users from copying its CDs. It used a rootkit to embed Sony's software in parts of the Windows operating system that make it hard to find by antispyware software and difficult to uninstall.
Beginning April 25, 2006, Microsoft's Windows Genuine Advantage Notifications application install on most Windows PCs as a "critical security update". While the main pupose of this deliberately uninstallable application is making sure the copy of Windows on the machine was lawfully purchased and installed, it also installs software that has been accused of "phoning home" on a daily basis, like spyware. It can be removed with the RemoveWGA tool.
Spyware and cookies
Anti-spyware programs often report Web advertisers' HTTP cookies, the small text files that track browsing activity, as spyware. While they are not inherently malicious, many users object to third parties using space on their personal computers for their business purposes, and so many anti-spyware programs offer to remove them.
Examples of spyware
These common spyware programs illustrate the diversity of behaviors found in these attacks. Note that as with computer viruses, researchers give names to spyware programs which may not be used by their creators. Programs may be grouped into "families" based not on shared program code, but on common behaviors, or by "following the money" of apparent financial or business connections. For instance, a number of the spyware programs distributed by Claria are collectively known as "Gator". Likewise, programs which are frequently installed together may be described as parts of the same spyware package, even if they function separately.
* CoolWebSearch, a group of programs, takes advantage of Internet Explorer vulnerabilities. The package directs traffic to advertisements on Web sites including coolwebsearch.com. It displays pop-up ads, rewrites search engine results, and alter the infected computer's hosts file to direct DNS lookups to these sites.
* Internet Optimizer, also known as DyFuCa, redirects Internet Explorer error pages to advertising. When users follow a broken link or enter an erroneous URL, they see a page of advertisements. However, because password-protected Web sites (HTTP Basic authentication) use the same mechanism as HTTP errors, Internet Optimizer makes it impossible for the user to access password-protected sites.
* 180 Solutions transmits detailed information to advertisers about the Web sites which users visit. It also alters HTTP requests for affiliate advertisements linked from a Web site, so that the advertisements make unearned profit for the 180 Solutions company. It opens pop-up ads that cover over the Web sites of competing companies. 
* HuntBar, aka WinTools or Adware.Websearch, is a small family of spyware programs distributed by Traffic Syndicate. It is installed by an ActiveX drive-by download at affiliate Web sites, or by advertisements displayed by other spyware programs an example of how spyware can install more spyware. These programs add toolbars to IE, track browsing behavior, redirect affiliate references, and display advertisements.
Legal issues related to spyware
Unauthorized access to a computer is illegal under computer crime laws, such as the U.S. Computer Fraud and Abuse Act, the U.K.'s Computer Misuse Act and similar laws in other countries. Since the owners of computers infected with spyware generally claim that they never authorized the installation, a prima facie reading would suggest that the promulgation of spyware would count as a criminal act. Law enforcement has often pursued the authors of other malware, particularly viruses. However, few spyware developers have been prosecuted, and many operate openly as strictly legitimate businesses, though some have faced lawsuits. 
Spyware producers argue that, contrary to the users' claims, users do in fact give consent to installations. Spyware that comes bundled with shareware applications may be described in the legalese text of an end-user license agreement (EULA). Many users habitually ignore these purported contracts, but spyware companies such as Claria claim these demonstrate that users have consented.
Despite the ubiquity of EULAs and of "clickwrap" agreements, under which a single click can be taken as consent to the entire text, relatively little case law has resulted from their use. It has been established in most common law jurisdictions that a clickwrap agreement can be a binding contract in certain circumstances. This does not, however, mean that every such agreement is a contract or that every term in one is enforceable.
Some jurisdictions, including the U.S. states of Iowa  and Washington , have passed laws criminalizing some forms of spyware. Such laws make it illegal for anyone other than the owner or operator of a computer to install software that alters Web-browser settings, monitors keystrokes, or disables computer-security software.
New York State Attorney General and Governor-elect Eliot Spitzer has pursued spyware companies for fraudulent installation of software. In a suit brought in 2005 by Spitzer, the California firm Intermix Media, Inc. ended up settling by agreeing to pay US$7.5 million and to stop distributing spyware.
The hijacking of Web advertisements has also led to litigation. In June 2002, a number of large Web publishers sued Claria for replacing advertisements, but settled out of court.
Courts have not yet had to decide whether advertisers can be held liable for spyware which displays their ads. In many cases, the companies whose advertisements appear in spyware pop-ups do not directly do business with the spyware firm. Rather, they have contracted with an advertising agency, which in turn contracts with an online subcontractor who gets paid by the number of "impressions" or appearances of the advertisement. Some major firms such as Dell Computer and Mercedes-Benz have sacked advertising agencies which have run their ads in spyware.
Libel suits by spyware developers
Litigation has gone both ways. Since "spyware" has become a common pejorative, some makers have filed libel and defamation actions when their products have been so described. In 2003, Gator (now known as Claria) filed suit against the website PC Pitstop for describing its program as "spyware". PC Pitstop settled, agreeing not to use the word "spyware", but continues to describe harm caused by the Gator/Claria software.  As a result, other antispyware and antivirus companies have also used other terms such as Potentially unwanted programs or greyware to denote these products.
Remedies and prevention
As the spyware threat has worsened, a number of techniques have emerged to counteract it. These include programs designed to remove or to block spyware, as well as various user practices which reduce the chance of getting spyware on a system.
Nonetheless, spyware remains a costly problem. When a large number of pieces of spyware have infected a Windows computer, the only remedy may involve backing up user data, and fully reinstalling the operating system.
Many programmers and some commercial firms have released products designed to remove or block spyware. Steve Gibson's OptOut, mentioned above, pioneered a growing category. Programs such as Lavasoft's Ad-Aware SE and Patrick Kolla's Spybot - Search & Destroy rapidly gained popularity as effective tools to remove, and in some cases intercept, spyware programs. More recently Microsoft acquired the GIANT AntiSpyware software, rebranding it as Windows AntiSpyware beta and releasing it as a free download for Windows XP and Windows 2003 users. In early spring, 2006, Microsoft renamed the beta software to Windows Defender, and it was released as a free download in October 2006. Microsoft has also announced that the product will ship (for free) with Windows Vista. Other well-known anti-spyware products include Webroot Spy Sweeper, Trend Micro's Anti-Spyware, PC Tools' Spyware Doctor, and Sunbelt's CounterSpy (which uses a forked codebase from the GIANT Anti-Spyware, now called Microsoft's Windows Defender). Blue Coat Systems released a gateway anti-spyware solution in 2004.
Major anti-virus firms such as Symantec, McAfee and Sophos have come later to the table, adding anti-spyware features to their existing anti-virus products. Early on, anti-virus firms expressed reluctance to add anti-spyware functions, citing lawsuits brought by spyware authors against the authors of web sites and programs which described their products as "spyware". However, recent versions of these major firms' home and business anti-virus products do include anti-spyware functions, albeit treated differently from viruses. Symantec Anti-Virus, for instance, categorizes spyware programs as "extended threats" and now offers real-time protection from them (as it does for viruses). Recently the anti virus company Grisoft, who make the AVG anti virus program, re-labled the Ewido anti spyware program as AVG anti Spyware program. This shows a trend by anti virus companies to launch a dedicated solution to spyware and malware. Zone Labs, who make the Zone Alarm firewall have also released an anti spyware program.
Anti-spyware programs can combat spyware in two ways:
* Real-time protection, which prevents the installation of spyware;
* Detection and removal, which removes spyware from an infected computer.
Writers of anti-spyware programs usually find detection and removal simpler, and many more programs have become available which do so. Such programs inspect the contents of the Windows registry, the operating system files, and installed programs, and remove files and entries which match a list of known spyware components. Real-time protection from spyware works identically to real-time anti-virus protection: the software scans incoming network data and disk files at download time, and blocks the activity of components known to represent spyware. In some cases, it may also intercept attempts to install start-up items or to modify browser settings. Because many spyware and adware are installed as a result of browser exploits or user error, using security software (some of which are antispyware, though many are not) to sandbox browsers can also be effective to help restrict any damage done.
Earlier versions of anti-spyware programs focused chiefly on detection and removal. Javacool Software's SpywareBlaster, one of the first to offer real-time protection, blocked the installation of ActiveX-based and other spyware programs. To date, other programs such as Ad-Aware and Windows Defender now combine the two approaches, while SpywareBlaster remains focused on prevention.
Like most anti-virus software, many anti-spyware/adware tools require a frequently-updated database of threats. As new spyware programs are released, anti-spyware developers discover and evaluate them, making "signatures" or "definitions" which allow the software to detect and remove the spyware. As a result, anti-spyware software is of limited usefulness without a regular source of updates. Some vendors provide a subscription-based update service, while others provide updates gratis. Updates may be installed automatically on a schedule or before doing a scan, or may be done manually.
Not all programs rely on updated definitions. Some programs rely partly (for instance many antispyware programs such as Windows Defender, Spybot's TeaTimer and Spysweeper) or fully (programs falling under the class of Hips such as BillP's WinPatrol), on historical observation. They watch certain configuration parameters (such as certain portions of the Windows registry or browser configuration) and report any change to the user, without judgment or recommendation. While they do not rely on updated definitions, which may allow them to spot newer spyware, they can offer no guidance. The user is left to determine "what did I just do, and is this configuration change appropriate?"
Windows Defender's Spynet attempts to alleviate this through offering a community to share information, which helps guide both users, who can look decisions made by others, and analysts, who can spot fast-spreading spyware. A popular generic spyware removal tool used by those with a certain degree of expertise is HijackThis, which scans certain areas of the Windows OS where spyware often resides and presents a list with items to delete manually. As most of the items are legitimate windows files/registry entries it is advised for those who are less knowledgeable on this subject to post a HijackThis log on the numerous antispyware sites and let the experts decide what to delete. Open source software is also available. One program, wssecure, can detect new processes and change in system files using checksum verification, a technique that can be helpful in detecting spyware that are downloaded automatically due to Windows vulnerabilities.
If a spyware program is not blocked and manages to get itself installed, it may resist attempts to terminate or uninstall it. Some programs work in pairs: when an anti-spyware scanner (or the user) terminates one running process, the other one respawns the killed program. Likewise, some spyware will detect attempts to remove registry keys and immediately add them again. Usually, booting the infected computer in safe mode allows an anti-spyware program a better chance of removing persistent spyware. Killing the process tree can also work.
A new breed of spyware (Look2Me spyware by NicTechNetworks is a good example) is starting to hide inside system-critical processes and start up even in safe mode. With no process to terminate they are harder to detect and remove. Sometimes they do not even leave any on-disk signatures. Rootkit technology is also seeing increasing use, as is the use of NTFS alternate data streams. Newer spyware programs also have specific countermeasures against well known anti-malware products and may prevent them from running or being installed, or even uninstall them. An example of one that uses all three methods is Gromozon, a new breed of malware. It uses alternate data streams to hide. A rootkit hides it even from alternate data streams scanners and actively stops popular rootkit scanners from running.
Fake anti-spyware programs
Malicious programmers have released a large number of fake anti-spyware programs, and widely distributed Web banner ads now spuriously warn users that their computers have been infected with spyware, directing them to purchase programs which do not actually remove spyware or worse, may add more spyware of their own.
The recent proliferation of fake or spoofed antivirus products has occasioned some concern. Such products often bill themselves as antispyware, antivirus, or registry cleaners, and sometimes feature popups prompting users to install them. They are called rogue software.
Known offenders include:
* The Shield 2006
* Privacy Defender
* Malware Wipe
* Pest Trap
* AntiVirus Gold
* Spyware Quake
* Spyware Stormer
* Spy Sheriff
* PAL Spyware Remover
* Trustcleaner Pro
* WinAntiVirus Pro 2006
On 2006-01-26, Microsoft and the Washington state attorney general filed suit against Secure Computer for its Spyware Cleaner product.
To deter spyware, computer users have found several practices useful in addition to installing anti-spyware programs.
Many system operators install a web browser other than IE, such as Opera or Mozilla Firefox. Although these have also suffered some security vulnerabilities, they are not targeted as much as IE because most users who are likely to fall for spyware are not using them. Though no browser is completely safe, Internet Explorer is at a greater risk for spyware infection due to its large user base as well as vulnerabilities such as ActiveX.
Some ISPs particularly colleges and universities have taken a different approach to blocking spyware: they use their network firewalls and web proxies to block access to Web sites known to install spyware. On March 31, 2005, Cornell University's Information Technology department released a report detailing the behavior of one particular piece of proxy-based spyware, Marketscore, and the steps the university took to intercept it. Many other educational institutions have taken similar steps. Spyware programs which redirect network traffic cause greater technical-support problems than programs which merely display ads or monitor users' behavior, and so may more readily attract institutional attention.
Some users install a large hosts file which prevents the user's computer from connecting to known spyware related web addresses. However, by connecting to the numeric IP address, rather than the domain name, spyware may bypass this sort of protection.
Spyware may get installed via certain shareware programs offered for download. Downloading programs only from reputable sources can provide some protection from this source of attack. Recently, CNet revamped its download directory: it has stated that it will only keep files that pass inspection by Ad-Aware and Spyware Doctor.
Notable programs distributed with spyware* BearShare
* Bonzi Buddy
* Dope Wars
* Sony's Extended Copy Protection involved the installation of spyware from audio compact discs through autorun. This practice sparked considerable controversy when it was discovered.
* WildTangent The antispyware program CounterSpy used to say that it's okay to keep WildTangent, but it now says that the spyware Winpipe is "possibly distributed with the adware bundler WildTangent or from a threat included in that bundler". 
* Drive Cleaner
Notable programs formerly distributed with spyware
* AOL Instant Messenger (AOL Instant Messenger still packages Viewpoint Media Player, and WildTangent)
* DivX (except for the paid version, and the "standard" version without the encoder). DivX announced removal of GAIN software from version 5.2.
* LimeWire (all free Windows versions up to 3.9.3)
* FlashGet (trial version prior to program being made freeware)
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