Spyware is computer software that is installed surreptitiously on a personal computer to intercept or take partial control over the user’s interaction with the computer, without the user’s informed consent.
While the term spyware suggests software that secretly monitors the user’s behavior, the functions of spyware extend well beyond simple monitoring. Spyware programs can collect various types of personal information, but can also interfere with user control of the computer in other ways, such as installing additional software, redirecting Web browser activity, or diverting advertising revenue to a third party.
In response to the emergence of spyware, a small industry has sprung up dealing in anti-spyware software. Running anti-spyware software has become a widely recognized element of computer security best practices for Microsoft Windows desktop computers. A number of jurisdictions have passed anti-spyware laws, which usually target any software that is surreptitiously installed to control a user’s computer.
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.
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.
Spyware can also come bundled with shareware or other downloadable software, as well as music CDs. The user downloads a program 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. Internet Explorer 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 optimize 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 Internet Explorer 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.
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 reinstallation of all their software in order to return to full functionality.
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 alters 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.
- Zango (formerly 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, was 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 aggregate browsing behavior, redirect affiliate references, and display advertisements.
- Movieland, also known as Moviepass.tv or Popcorn.net, is a movie download service that has been the subject of thousands of complaints to the Federal Trade Commission (FTC), the Washington State Attorney General’s Office, the Better Business Bureau, and others by consumers claiming they were held hostage by its repeated pop-up windows and demands for payment. The FTC has filed a complaint against Movieland.com and eleven other defendants (list), charging them with having “engaged in a nationwide scheme to use deception and coercion to extract payments from consumers.” The complaint alleges that the software repeatedly opened oversized pop-up windows that could not be closed or minimized, accompanied by music that lasted nearly a minute, demanding payment of at least $29.95 to end the pop-up cycle; and claiming that consumers had signed up for a three-day free trial but did not cancel their membership before the trial period was over, and were thus obligated to pay.
Report on scan of an infected system from Lavasoft’s Ad-Aware
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 Genuine 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 currently ships the product for free with Windows Vista. Other well-known anti-spyware products include:
- Webroot Spy Sweeper
- Trend Micro‘s Anti-Spyware
- PC Tools’ Spyware Doctor
- Sunbelt Software‘s CounterSpy V2
- Blue Coat Systems‘ anti-spyware
- ParetoLogic Anti-Spyware and XoftSpySE
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, creator of AVG anti-virus program, acquired anti-spyware firm Ewido Networks, re-labeling their Ewido anti-spyware program as AVG Anti-Spyware. This shows a trend by anti virus companies to launch a dedicated solution to spyware and malware. Zone Labs, creator of Zone Alarm firewall have also released an anti spyware program.
Microsoft Anti-Spyware, in real-time protection blocks an instance of the AlwaysUpdateNews from being installed.
Anti-spyware programs can combat spyware in two ways:
- 1. They can provide real time protection against the installation of spyware software on your computer. This type of spyware protection works the same way as that of anti-virus protection in that the anti-spyware software scans all incoming network data for spyware software and blocks any threats it comes across.
- 2. Anti-spyware software programs can be used solely for detection and removal of spyware software that has already been installed onto your computer. This type of spyware protection is normally much easier to use and more popular. With this spyware protection software you can schedule weekly, daily, or monthly scans of your computer to detect and remove any spyware software that has been installed on your computer. This type of anti-spyware software scans the contents of the windows registry, operating system files, and installed programs on your computer and will provide a list of any threats found, allowing you to choose what you want to delete and what you want to keep.
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 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.
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 free. 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 at 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.
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.
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, their comparatively small market share compared to Internet Explorer makes it uneconomic for hackers to target users on those browsers. 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.