Rootkit

A rootkit is a stealthy type of malicious software (malware) designed to hide the existence of certain processes or programs from normal methods of detection and enables continued privileged access to a computer. The term rootkit is a concatenation of "root" (the traditional name of the privileged account on Unix operating systems) and the word "kit" (which refers to the software components that implement the tool). The term "rootkit" has negative connotations through its association with malware.

Rootkit installation can be automated, or an attacker can install it once they've obtained root or Administrator access. Obtaining this access is either a result of direct attack on a system (ie. exploiting a known vulnerability, password (either by cracking, privilege escalation, or social engineering). Once installed it becomes possible to hide the intrusion as well as to maintain privileged access. Like any software they can have a good purpose or a malicious purpose. The key is the root/Administrator access. Full control over a system means that existing software can be modified, including software that might otherwise be used to detect or circumvent it.

Rootkit detection is difficult because a rootkit may be able to subvert the software that is intended to find it. Detection methods include using an alternative, trusted operating system; behavioral-based methods; signature scanning; difference scanning; and memory dump analysis. Removal can be complicated or practically impossible, especially in cases where the rootkit resides in the kernel; reinstallation of the operating system may be the only available solution to the problem. When dealing with firmware rootkits, removal may require hardware replacement, or specialised equipment.

The first documented computer virus to target the PC platform, discovered in 1986, used cloaking techniques to hide itself: the Brain virus intercepted attempts to read the boot sector, and redirected these to elsewhere on the disk, where a copy of the original boot sector was kept. Over time, DOS-virus cloaking methods became more sophisticated, with advanced techniques including the hooking of low-level disk INT 13H BIOS interrupt calls to hide unauthorized modifications to files.History

The term rootkit or root kit originally referred to a maliciously-modified set of administrative tools for a Unix-like operating system that granted "root" access. If an intruder could replace the standard administrative tools on a system with a rootkit, the intruder could obtain root access over the system whilst simultaneously concealing these activities from the legitimate system administrator. These first generation rootkits were trivial to detect by using tools such as Tripwire that had not been compromised to access the same information. Lane Davis and Steven Dake wrote the earliest known rootkit in 1990 for Sun Microsystems' SunOS UNIX operating system. Ken Thompson of Bell Labs, one of the creators of Unix, subverted the C compiler in a Unix distribution and discussed the exploit in the lecture he gave upon receiving the Turing award in 1983. The modified compiler would detect attempts to compile the Unix "login" command and generate altered code that would accept not only the user's correct password, but an additional password known to the attacker. Additionally, the compiler would detect attempts to compile a new version of the compiler, and would insert the same exploits into the new compiler. A review of the source code for the "login" command or the updated compiler would not reveal any malicious code. This exploit was equivalent to a rootkit.

The first malicious rootkit for the Windows NT operating system appeared in 1999: a trojan called NTRootkit created by Greg Hoglund. It was followed byHackerDefender in 2003. The first rootkit targeting Mac OS X appeared in 2009, while the Stuxnet worm was the first to target programmable logic controllers(PLC).

Sony BMG copy protection rootkit scandal

Screenshot of RootkitRevealer, showing the files hidden by the Extended Copy Protection rootkit

Main article: Sony BMG copy protection rootkit scandal

In 2005, Sony BMG published CDs with copy protection and digital rights management software called Extended Copy Protection, created by software company First 4 Internet. The software included a music player but silently installed a rootkit which limited the user's ability to access the CD.

Software engineer Mark Russinovich, who created the rootkit detection tool RootkitRevealer, discovered the rootkit on one of his computers. The ensuing scandal raised the public's awareness of rootkits.

To cloak itself, the rootkit hid from the user any file starting with "$sys$". Soon after Russinovich's report, malware appeared which took advantage of that vulnerability of affected systems.

One BBC analyst called it a "public relations nightmare." Sony BMG released patches to uninstall the rootkit, but it exposed users to an even more serious vulnerability. The company eventually recalled the CDs. In the United States, a class-action lawsuit was brought against Sony BMG.

Greek wiretapping case 2004–05

Main article: Greek wiretapping case 2004–2005

The Greek wiretapping case of 2004-05, also referred to as Greek Watergate, involved the illegal tapping of more than 100 mobile phones on the Vodafone Greece network belonging mostly to members of the Greek government and top-ranking civil servants. The taps began sometime near the beginning of August 2004 and were removed in March 2005 without discovering the identity of the perpetrators.

In order to carry out the wiretapping, the intruders installed a rootkit that targeted Ericsson's AXE telephone exchange. According to IEEE Spectrum, this was "the first time a rootkit has been observed on a special-purpose system, in this case an Ericsson telephone switch." The rootkit was designed to patch the memory of the exchange while it was running, enable wiretapping whilst disabling audit logs, patch the commands that list active processes and active data blocks, and modify the data block checksum verification command. A backdoor allowed an operator with sysadmin status to deactivate the exchange's transaction log and alarms, and access commands related to the surveillance capability. The rootkit was discovered after the intruders installed a faulty update, which caused SMStexts to be undelivered, leading to an automated failure report being generated. Ericsson engineers were called in to investigate the fault, and at this point discovered the hidden data blocks containing the list of phone numbers being monitored, along with the rootkit and illicit monitoring software that had been installed.

Uses

Modern rootkits do not elevate access, but rather are used to make another software payload undetectable by adding stealth capabilities. Most rootkits are classified as malware, because the payloads they are bundled with are malicious. For example, a payload might covertly steal user passwords, credit cardinformation, computing resources, or conduct other unauthorized activities. A small number of rootkits may be considered utility applications by their users: for example, a rootkit might cloak a CD-ROM-emulation driver, allowing video game users to defeat anti-piracy measures that require insertion of the original installation media into a physical optical drive to verify that the software was legitimately purchased.

Rootkits and their payloads have many uses:

• Provide an attacker with full access via a backdoor, permitting unauthorized access to, for example, steal or falsify documents. One of the ways to carry this out is to subvert the login mechanism, such as the /bin/login program on Unix-like systems or GINA on Windows. The replacement appears to function normally, but also accepts a secret login combination that allows an attacker direct access to the system with administrative privileges, bypassing standardauthentication and authorization mechanisms.
• Conceal other malware, notably password-stealing key loggers and computer viruses.
• Appropriate the compromised machine as a zombie computer for attacks on other computers. (The attack originates from the compromised system or network, instead of the attacker's system.) "Zombie" computers are typically members of large botnets that can launch denial-of-service attacks and distribute e-mailspam.
• Enforcement of digital rights management (DRM).

In some instances, rootkits provide beneficial functionality, and may be installed intentionally by the computer owner:

• Conceal cheating in online games from software like Warden.
• Detect attacks, for example, in a honeypot.
• Enhance emulation software and security software. Alcohol 120% and Daemon Tools are commercial examples of non-hostile rootkits used to defeat copy-protection mechanisms such as SafeDisc and SecuROM. Kaspersky antivirus software also uses techniques resembling rootkits to protect itself from malicious actions. It loads its own drivers to intercept system activity, and then prevents other processes from doing harm to itself. Its processes are not hidden, but cannot be terminated by standard methods.
• Anti-theft protection: Laptops may have BIOS-based rootkit software that will periodically report to a central authority, allowing the laptop to be monitored, disabled or wiped of information in the event that it is stolen.
• Bypassing Microsoft Product Activation

Types

Further information: Ring (computer security)

There are at least five types of rootkit, ranging from those at the lowest level in firmware (with the highest privileges), through to the least privileged user-based variants that operate in Ring 3. Hybrid combinations of these may occur spanning, for example, user mode and kernel mode.

User-mode

Computer security rings (Note thatRing ‑1 is not shown)

User-mode rootkits run in Ring 3, along with other applications as user, rather than low-level system processes. They have a number of possible installation vectors to intercept and modify the standard behavior of application programming interfaces (APIs). Some inject a dynamically-linked library (such as a .DLL file on Windows, or a .dylib file on Mac OS X) into other processes, and are thereby able to execute inside any target process to spoof it; others with sufficient privileges simply overwrite the memory of a target application. Injection mechanisms include:

• Use of vendor-supplied application extensions. For example, Windows Explorer has public interfaces that allow third parties to extend its functionality.
• Interception of messages.
• Debuggers.
• Exploitation of security vulnerabilities.
• Function hooking or patching of commonly used APIs, for example, to mask a running process or file that resides on a filesystem.

...since user mode applications all run in their own memory space, the rootkit needs to perform this patching in the memory space of every running application. In addition, the rootkit needs to monitor the system for any new applications that execute and patch those programs' memory space before they fully execute.

—Windows Rootkit Overview, Symantec

Kernel-mode

Kernel-mode rootkits run with the highest operating system privileges (Ring 0) by adding code or replacing portions of the core operating system, including both thekernel and associated device drivers. Most operating systems support kernel-mode device drivers, which execute with the same privileges as the operating system itself. As such, many kernel-mode rootkits are developed as device drivers or loadable modules, such as loadable kernel modules in Linux or device drivers inMicrosoft Windows. This class of rootkit has unrestricted security access, but is more difficult to write. The complexity makes bugs common, and any bugs in code operating at the kernel level may seriously impact system stability, leading to discovery of the rootkit. One of the first widely-known kernel rootkits was developed for Windows NT 4.0 and released in Phrack magazine in 1999 by Greg Hoglund.

Kernel rootkits can be especially difficult to detect and remove because they operate at the same security level as the operating system itself, and are thus able to intercept or subvert the most trusted operating system operations. Any software, such as antivirus software, running on the compromised system is equally vulnerable. In this situation, no part of the system can be trusted.

A rootkit can modify data structures in the Windows kernel using a method known as direct kernel object modification (DKOM). This method can hook kernel functions in the System Service Descriptor Table (SSDT), or modify the gates between user mode and kernel mode, in order to cloak itself. Similarly for the Linuxoperating system, a rootkit can modify the system call table to subvert kernel functionality. It's not uncommon for a rootkit to create a hidden, encrypted filesystem in which it can hide other malware or original copies of files it has infected.

Operating systems are evolving to counter the threat of kernel-mode rootkits. For example, 64-bit editions of Microsoft Windows now implement mandatory signing of all kernel-level drivers in order to make it more difficult for untrusted code to execute with the highest privileges in a system.

Bootkits

A kernel-mode rootkit variant called a bootkit is used predominantly to attack full disk encryption systems, for example as in the "Evil Maid Attack", in which a bootkit replaces the legitimate boot loader with one controlled by an attacker; typically the malware loader persists through the transition to protected mode when the kernel has loaded. For example, the "Stoned Bootkit" subverts the system by using a compromised boot loader to intercept encryption keys and passwords. More recently, the Alureon rootkit has successfully subverted the requirement for 64-bit kernel-mode driver signing in Windows 7 by modifying themaster boot record.

The only known defenses against bootkit attacks are the prevention of unauthorized physical access to the system—a problem for portable computers—or the use of a Trusted Platform Module configured to protect the boot path.

Hypervisor level

Rootkits have been created as Type II Hypervisors in academia as proofs of concept. By exploiting hardware virtualization features such as Intel VT or AMD-V, this type of rootkit runs in Ring -1 and hosts the target operating system as a virtual machine, thereby enabling the rootkit to intercept hardware calls made by the original operating system. Unlike normal hypervisors, they do not have to load before the operating system, but can load into an operating system before promoting it into a virtual machine. A hypervisor rootkit does not have to make any modifications to the kernel of the target to subvert it; however, that does not mean that it cannot be detected by the guest operating system. For example, timing differences may be detectable in CPU instructions. The "SubVirt" laboratory rootkit, developed jointly by Microsoft and University of Michigan researchers, is an academic example of a virtual machine–based rootkit (VMBR), while Blue Pill is another.

In 2009, researchers from Microsoft and North Carolina State University demonstrated a hypervisor-layer anti-rootkit called Hooksafe, which provides generic protection against kernel-mode rootkits.

Hardware/Firmware

A firmware rootkit uses device or platform firmware to create a persistent malware image in hardware, such as a network card, hard drive, or the systemBIOS.The rootkit hides in firmware, because firmware is not usually inspected for code integrity. John Heasman demonstrated the viability of firmware rootkits in both ACPI firmware routines and in a PCI expansion card ROM.

In October 2008, criminals tampered with European credit-card-reading machines before they were installed. The devices intercepted and transmitted credit card details via a mobile phone network. In March 2009, researchers Alfredo Ortega and Anibal Sacco published details of a BIOS-level Windows rootkit that was able to survive disk replacement and operating system re-installation. A few months later they found that some laptops are sold with a legitimate rootkit, known as CompuTrace or LoJack for Laptops, preinstalled in the BIOS. This is an anti–theft technology system that researchers showed can be turned to malicious purposes.

Removal

Manual removal of a rootkit is often too difficult for a typical computer user, but a number of security-software vendors offer tools to automatically detect and remove some rootkits, typically as part of an antivirus suite. As of 2005, Microsoft's monthly Windows Malicious Software Removal Tool is able to detect and remove some classes of rootkits. Some antivirus scanners can bypass file system APIs, which are vulnerable to manipulation by a rootkit. Instead, they access raw filesystem structures directly, and use this information to validate the results from the system APIs to identify any differences that may be caused by a rootkit.

There are experts who believe that the only reliable way to remove them is to re-install the operating system from trusted media. This is because antivirus and malware removal tools running on an untrusted system may be ineffective against well-written kernel-mode rootkits. Booting an alternate operating system from trusted media can allow an infected system volume to be mounted and potentially safely cleaned and critical data to be copied off—or, alternatively, a forensic examination performed. Lightweight operating systems such as Windows PE, Windows Recovery Console, Windows Recovery Environment, BartPE, or Live Distros can be used for this purpose, allowing the system to be cleaned.

Even if the type and nature of a rootkit is known, manual repair may be impractical, while re-installing the operating system and applications is safer, simpler and quicker.

Spyware

From Wikipedia, the free encyclopedia

Spyware is a type of malware (malicious software) installed on computers that collects information about users without their knowledge. The presence of spyware is typically hidden from the user and can be difficult to detect. Spyware is often secretly installed on a user's personal computer without their knowledge. However, some spyware such as keyloggers may be installed by the owner of a shared, corporate, or public computer on purpose in order to intentionally monitor users.

While the term spyware suggests software that monitors a user's computing, the functions of spyware can extend beyond simple monitoring. Spyware can collect almost any type of data, including personal information like Internet surfing habits, user logins, and bank or credit account information. Spyware can also interfere with user control of a computer by installing additional software or redirecting Web browsers. Some spyware can change computer settings, resulting in slow Internet connection speeds, un-authorized changes in browser settings or functionality of other software.

Sometimes, spyware is included along with genuine software, and may come from an official software vendor. In an attempt to increase the understanding of spyware, a more formal classification of its included software types is provided by the term privacy-invasive software. 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 securitypractices for computers, especially those running Microsoft Windows. A number of jurisdictions have passed anti-spyware laws, which usually target any software that is surreptitiously installed to control a user's computer.

History and development

The first recorded use of the term spyware occurred on 16 October 1995 in a Usenet post that poked fun at Microsoft's business model. Spyware at first denotedsoftware 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.

According to a 2005 study by AOL and the National Cyber-Security Alliance, 61 percent of surveyed users' computers were infected with form of spyware. 92 percent of surveyed users with spyware reported that they did not know of its presence, and 91 percent 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. Computers on which 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 access to crucial parts of the operating system.

Before Internet Explorer 6 SP2 was released as part of Windows XP Service Pack 2, the browser would automatically display an installation window for any ActiveXcomponent that a website wanted to install. The combination of user ignorance about these changes, and the assumption by Internet Explorer that all ActiveX components are benign, helped to spread spyware significantly. Many spyware components would also make use of exploits in Javascript, Internet Explorer and Windows to install without user knowledge or permission.

The Windows Registry contains multiple sections where modification of key values allows software to be executed automatically when the operating system boots. Spyware can exploit this design to circumvent attempts at removal. The spyware typically will link itself from each location in the registry that allows execution. Once running, the spyware will periodically check if any of these links are removed. If so, they will be automatically restored. This ensures that the spyware will execute when the operating system is booted, even if some (or most) of the registry links are removed.

Comparison

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 may be classified 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 adware is spyware in a different sense than "advertising-supported software": it displays advertisements related to what it finds from spying on users. Gator Software from Claria Corporation (formerly GATOR) 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 is shown 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 on other programs that track Web browsing, even for statistical or research purposes. Some observers describe theAlexa Toolbar, an Internet Explorer plug-in published by Amazon.com, as spyware, and some anti-spyware programs such as Ad-Aware report it as such. Many of these adware-distributing companies are backed by millions of dollars of adware-generating revenues. Adware and spyware are similar to viruses in that they can be considered malicious in nature. People are profiting from misleading adware, sometimes known as scareware, such as Antivirus 2009.

Similarly, software bundled with free, advertising-supported programs acts as spyware (and, if removed, disables the 'parent' program), yet people are willing to download it. This presents a dilemma for proprietors of anti-spyware products whose removal tools may inadvertently disable wanted programs. For example,WhenUSave is ignored by popular anti-spyware program Ad-Aware (but removed as spyware by most scanners) because it is part of the popular (but recently decommissioned) eDonkey client. To address this dilemma, the Anti-Spyware Coalition was formed in 2005 to establish and document best practices regarding acceptable software behavior. Its website however does not appear to have been updated since late 2008.

Spyware, viruses and worms

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 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, and routing of HTTP requests to advertising sites.

However, spyware can be dropped as a payload by a worm.

Routes of infection

Malicious websites attempt to install spyware on readers' computers.

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' knowledge. 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 bypiggybacking on a piece of desirable software such as Kazaa, or by tricking them into installing it (the Trojan horse method). Some "rogue" spyware programs 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 program bundled with spyware and 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 other software. 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 freeware with installers that slipstream spyware.

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 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 Sun Microsystems 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 behavior 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 profit personally.

Effects and behaviors

A spyware program is rarely alone on a computer: an affected machine usually has multiple infections. Users frequently notice unwanted behavior and degradation of system performance. A spyware infestation can create significant unwanted CPU activity, disk usage, and network traffic. Stability issues, such as applications freezing, failure to boot, and 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 performance issues relate to faulty hardware, Windows installation problems, or another infection. 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.

Only rarely does a single piece of software render a computer unusable. Rather, a computer is likely to have multiple infections. The cumulative effect, and the interactions between spyware components, causes 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. Some spyware disables or even removes competing spyware programs, on the grounds that more spyware-related annoyances make it even more likely that users will take action to remove the programs. One spyware maker, Avenue Media, even sued a competitor, Direct Revenue, over this; the two later settled with an agreement not to disable each others' products.

Some other types of spyware use rootkit like techniques to prevent detection, and thus removal. Targetsoft, for instance, modifies the "Winsock" Windows Sockets files. The deletion of the spyware-infected file "inetadpt.dll" will interrupt normal networking usage.

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. As with other operating systems, Windows users too are able to follow the principle of least privilege and use non-administrator least user access accounts, or to reduce the privileges of specific vulnerable Internet-facing processes such as Internet Explorer (through the use of tools such asDropMyRights). However, as this is not a default configuration, few users do this.

In Windows Vista, by default, a computer administrator runs everything under limited user privileges. When a program requires administrative privileges, Vista will prompt the user with an allow/deny pop-up (see User Account Control). This improves on the design used by previous versions of Windows.

Advertisements

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 the user visiting specific sites. 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.

Many users complain about irritating or offensive advertisements as well. As with many banner ads, spyware advertisements often use animation or flickering banners, which can be visually distracting and annoying to users. Pop-up ads for pornography often display indiscriminately. Links to these sites may be added to the browser window, history or search function. When children are the users, this could possibly violate anti-pornography laws in some jurisdictions.

A number of spyware programs break the boundaries of illegality; variations of “Zlob.Trojan” and “Trojan-Downloader.Win32.INService” have been known to show undesirable child pornography, key gens, cracks and illegal software pop-up ads, which violate child pornography and copyright laws.

A further issue in the case of some spyware programs concerns the replacement of banner ads on viewed web sites. Spyware that acts as a web proxy or aBrowser 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 termsaffiliate fraud, a form of 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 activity — replacing 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 suspected the creators of the common CoolWebSearch spyware had used it to transmit "chat sessions, user names, passwords, bank information, etc."; however 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.

The Federal Trade Commission estimates that 27.3 million Americans have been victims of identity theft, and that financial losses from identity theft totaled nearly $48 billion for businesses and financial institutions and at least $5 billion in out-of-pocket expenses for individuals.

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 usualISP. Connecting to these suspicious numbers involves long-distance or overseas charges which invariably result in high call costs. Dialers are ineffective on computers that do not have a modem, or are not connected to a telephone line, and are now very rare due to the decline in use of dial-up internet access.

Digital rights management

Some copy-protection technologies have borrowed from spyware. In 2005, Sony BMG Music Entertainment was found to be using rootkits in its XCP digital rights management technology Like spyware, not only was it difficult to detect and uninstall, it was so poorly written that most efforts to remove it could have rendered computers unable to function. Texas Attorney General Greg Abbott filed suit, and three separate class-action suits were filed. Sony BMG later provided a workaround on its website to help users remove it.

Beginning on 25 April 2006, Microsoft's Windows Genuine Advantage Notifications application was installed on most Windows PCs as a "critical security update". While the main purpose of this deliberately uninstallable application is to ensure 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.

Personal relationships

Spyware has been used to surreptitiously monitor electronic activities of partners in intimate relationships, generally to uncover evidence of infidelity. At least one software package, Loverspy, was specifically marketed for this purpose. Depending on local laws regarding communal/marital property, observing a partner's online activity without their consent may be illegal; the author of Loverspy and several users of the product were indicted in California in 2005 on charges of wiretapping and various computer crimes.

Browser cookies

Anti-spyware programs often report Web advertisers' HTTP cookies, the small text files that track browsing activity, as spyware. While they are not always inherently malicious, many users object to third parties using space on their personal computers for their business purposes, and many anti-spyware programs offer to remove them.

Examples

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 that 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.

• 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 and 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 other agencies. Consumers complained they were held hostage by a cycle of oversized pop-up windows demanding payment of at least $29.95, claiming that they had signed up for a three-day free trial but had not cancelled before the trial period was over, and were thus obligated to pay. The FTC filed a complaint, since settled, against Movieland and eleven other defendants charging them with having "engaged in a nationwide scheme to use deception and coercion to extract payments from consumers."

• WeatherStudio has a plugin that displays a window-panel near the bottom of a browser window. The official website notes that it is easy to remove (uninstall) WeatherStudio from a computer, using its own uninstall-program, such as under C:\Program Files\WeatherStudio. Once WeatherStudio is removed, a browser returns to the prior display appearance, without the need to modify the browser settings.

• Zango (formerly 180 Solutions) transmits detailed information to advertisers about the Web sites which users visit. It also alters HTTP requests for affiliateadvertisements 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 (as seen in their [Zango End User License Agreement]).

• Zlob trojan, or just Zlob, downloads itself to a computer via an ActiveX codec and reports information back to Control Server. Some information can be the search-history, the Websites visited, and even keystrokes.^{[citation needed]} More recently, Zlob has been known to hijack routers set to defaults.