[Blog](/blog) Show links Resources [Blog](/blog) [Breaches](/breaches) [eBooks, reports, & more](/resources) [Events](/events) [News](/news) [Cybersecurity](/category/cybersecurity) Show links Categories [Attack Surface Management](/category/attack-surface-management) [Company News](/category/company-news) [Compliance and Regulations](/category/compliance-and-regulations) [Cybersecurity](/category/cybersecurity) [Data Breaches](/category/data-breaches) [DevOps](/category/devops) [Human Cyber Risk](/category/human-cyber-risk) [Risks and Vulnerabilities](/category/risks-and-vulnerabilities) [Third-Party Risk Management](/category/third-party-risk-management) [Vendor Risk Management](/category/vendor-risk-management) [What is Spyware?](/blog/spyware) Publish date July 8, 2025 {x} minute read # What is Spyware? [Get a demo](/contact-sales) [Free trial](/demo) [Download the PDF guide](/resources/complete-guide-to-data-breaches) [Free trial](/demo) Written by [Abi Tyas Tunggal](/team/abi-tyas-tunggal) Writer and Senior Product Manager at UpGuard. Abi's work has influenced leaders across cybersecurity, technology, and financial services. Reviewed by [Kaushik Sen](/team/kaushik-sen) Chief Marketing Officer Kaushik has a background in software engineering, enterprise solution architecture, and data analytics. He brings a unique, data-driven perspective to cybersecurity education. Table of contents eBook A Complete Guide to Data Breaches Free resource ### A Complete Guide to Data Breaches Learn how to avoid a costly data breach with a comprehensive prevention strategy. [Download now](/resources/complete-guide-to-data-breaches) Spyware is unwanted software, a [type of malicious software](https://www.upguard.com/blog/types-of-malware) or [malware](https://www.upguard.com/blog/malware), designed to expose [sensitive information](https://www.upguard.com/blog/sensitive-data), steal internet usage data, gain access to or damage your computing device. Any software downloaded to a user's device without authorization can be classified as spyware. Even spyware programs installed for innocuous reasons often violate end user privacy agreements and have the potential for abuse.  Spyware is a [cyber threat](https://www.upguard.com/blog/cyber-threat), primarily due to the risk of exposing personal information, credit card numbers, [protected health information (PHI)](https://www.upguard.com/blog/protected-health-information-phi), keystrokes, [personally identifiable information (PII)](https://www.upguard.com/blog/personally-identifiable-information-pii) or login credentials. ## How Does Spyware Work? In its least damaging form, spyware runs in the background creating unwanted CPU activity, disk usage, hindered Internet connections, stability issues, application freezes, failure to boot and system-wide crashes.  These infects may not be evident to users who assume performance issues are related to faulty or outdated software, installation problems or a different [malware](https://www.upguard.com/blog/malware) infection. This can result in technical support costs and users buying a new computer due to their existing system becoming too slow.   More aggressive forms of spyware reset browser homepages, open pop-up ads, redirect web searches and impact browser security.  At its most damaging, spyware tracks all computer related activity, exposes [sensitive data](https://www.upguard.com/blog/sensitive-data), password, credit card numbers, banking details aiding in [identity theft](https://www.upguard.com/blog/identity-theft) and [corporate espionage](https://www.upguard.com/blog/corporate-espionage) or additional [cyber attacks](https://www.upguard.com/blog/cyber-attack).   Some types of spyware will disable firewalls and antivirus software, reduce browser security settings and open up new [attack vectors](https://www.upguard.com/blog/attack-vector). Aggressive variants aim to disable or remove competing spyware programs to decrease the likelihood the victim will take action or invest in a spyware removal tool.  ## What Devices Can Be Infected By Spyware? Spyware can infect PCs, Macs, iOS, Android, Unix and many other operating systems, with the Microsoft Windows operating system representing the largest [cybersecurity risk](https://www.upguard.com/blog/cybersecurity-risk) due to the majority of spyware creators targeting those machines. This has been driven by Window's widespread popularity over Apple and other Unix based operating systems. ## How Do Spyware Infections Happen? Spyware is distributed in a number of ways. A common method is to trick users into visiting a malicious website, through email, text messages, pop-ups or ads.  Users can even become infected when they take no action. In some situations, infected ads are delivered to would-be victims via a legitimate website in a practice known as malvertising.  Cybercriminals may distribute spyware via [social engineering](https://www.upguard.com/blog/social-engineering), [phishing](https://www.upguard.com/blog/phishing) or [spear phishing](https://www.upguard.com/blog/spear-phishing) emails designed to look like they originate from a trusted source. Or users might download legitimate software with spyware bundled with it, such as when mobile spyware is bundled in with legitimate apps and slips through Google and Apple's screening processes, ending up on the Google Play or App Store.   It's important to understand that spyware doesn't necessarily spread in the same way as other [types of malware](https://www.upguard.com/blog/types-of-malware) or [computer worms](https://www.upguard.com/blog/computer-worm). In general, spyware is not concerned with transmitting or copying itself to other devices.  Rather spyware installs itself by deceiving the user, bundling itself with desirable software or by exploiting [vulnerabilities](https://www.upguard.com/blog/vulnerability) in web browsers and operating systems. Internet Explorer is a frequent target due to its popularity, history of security issues, deep integration with the Windows operating system and Browser Helper Objects which allow attackers to modify the browser's behavior. These vulnerabilities are often well-known, patched and listed on [CVE](https://www.upguard.com/blog/cve).  ## What are the Types of Spyware? Spyware can be classified into nine categories: 1. **Adware:** Any software that displays advertisements while the programming is running, often in a web browser or pop-up ads. Adware is typically bundled with freeware or piggybacks on another program to trick you into installing it on your computer, tablet or smartphone.  2. **Tracking cookies:** Tracks the user's browsing habits and online activities, such as web page visits, searches, history and downloads for marketing purposes. Advertisers like Facebook and Google use cookies to track internet activity to better target advertising.  3. **Trojan horse:** Any program that misleads users of its true intent by masquerading as a legitimate program. The term is derived from the Ancient Greek story of the deceptive Trojan Horse that led to the fall of the city of Troy. Trojans typically spread through [social engineering](https://www.upguard.com/blog/social-engineering), infected email attachments, [phishing](https://www.upguard.com/blog/phishing) and [spear phishing](https://www.upguard.com/blog/spear-phishing) campaigns. Once installed, trojans can expose [sensitive data](https://www.upguard.com/blog/sensitive-data) and carry out additional [cyber attacks](https://www.upguard.com/blog/cyber-attack) like [ransomware](https://www.upguard.com/blog/ransomware).   4. **Keyloggers: **[Keyloggers are a type of system monitoring software](https://www.upguard.com/blog/what-is-a-keylogger) used by cybercriminals to steal [personally identifiable information (PII)](https://www.upguard.com/blog/personally-identifiable-information-pii), [protected health information (PHI)](https://www.upguard.com/blog/protected-health-information-phi) and enterprise data to use in identity theft and [corporate espionage](https://www.upguard.com/blog/corporate-espionage). Keyloggers are also used by employers to observe employees' computer activity, parents to supervise a child's internet usage, device owners to track unauthorized activity, law enforcement agencies for [digital forensics](https://www.upguard.com/blog/digital-forensics) or competitors for [industrial espionage](https://www.upguard.com/blog/corporate-espionage).  5. **Stalkerware: **Typically installed on mobile devices so the owner of the phone's activity and location can be tracked by a [third-party](https://www.upguard.com/blog/third-party-vendor). 6. **Stealware: **Intercepts requests, often for online payments, and steals the victim's credit card information. 7. **System monitors:** Records activities on a device, from keystrokes and emails to websites visited and programs launched. System monitors can be used by [cybersecurity](https://www.upguard.com/blog/cyber-security) teams to monitor a system's processes, identify [vulnerabilities](https://www.upguard.com/blog/vulnerability), install software programs, plugins, security software or antivirus software, adjust security settings and remotely wipe hard drives. Cybercriminals can also use system monitors to [exploit](https://www.upguard.com/blog/exploit) those same [attack vectors](https://www.upguard.com/blog/attack-vector). 8. **Web beacons:** Used to unobtrusively track whether a user has accessed a piece of content, generally used for web analytics, page tagging or email tracking. Web beacons allow companies to track the online behavior of users. 9. **Mobile spyware: **Generally spreads through smishing, infected apps or text messages that [exploit](https://www.upguard.com/blog/exploit) a [vulnerability](https://www.upguard.com/blog/vulnerability) and don't require user interaction to execute. Once infected, [smartphones or tablets can expose](https://www.upguard.com/blog/can-sim-cards-get-hacked) the user's location, camera, microphone, phone calls, keystrokes and browsing activity.  ## How to Prevent Spyware As the threat of spyware has increased, so too have the number of techniques to counteract it. Some best practices include: * [Monitoring for leaked credentials](https://www.upguard.com/product/breach-risk/threat-monitoring), data leaks and data breaches * Only downloading software from trusted sources * Reading all disclosures when installing software * Avoiding interaction with or blocking online advertisements * Keeping operating systems and other software up-to-date to avoid known [vulnerabilities](https://www.upguard.com/blog/vulnerability) * Using the [principle of least privilege](https://www.upguard.com/blog/principle-of-least-privilege) and [access control](https://www.upguard.com/blog/access-control) to limit what types of software can be installed by users * Investing in [cybersecurity](https://www.upguard.com/blog/cyber-security) awareness training to educate staff about the dangerous of [social engineering](https://www.upguard.com/blog/social-engineering), [phishing](https://www.upguard.com/blog/phishing) and [spear phishing](https://www.upguard.com/blog/spear-phishing) campaigns that may be used to deliver infected email attachments * Using [DMARC](https://www.upguard.com/blog/dmarc) to minimize the risk of [email spoofing](https://www.upguard.com/blog/email-spoofing) * Avoiding pirated media including games, movies and music * Using [two-factor authentication](https://www.upguard.com/blog/two-factor-authentication) and/or [biometrics](https://www.upguard.com/blog/biometrics) * Investing in reputable anti-spyware, antivirus and [cybersecurity software](https://www.upguard.com/) * Requiring remote workers to use a virtual private network to prevent [man-in-the-middle attacks](https://www.upguard.com/blog/man-in-the-middle-attack) before accessing network resources * Following the [NIST Cybersecurity Framework](https://www.upguard.com/blog/nist-cybersecurity-framework) * Developing an [information security policy](https://www.upguard.com/blog/information-security-policy) and [information risk management program](https://www.upguard.com/blog/information-risk-management) * Employing a [defense in depth](https://www.upguard.com/blog/defense-in-depth) strategy that covers [information security](https://www.upguard.com/blog/information-security), [data security](https://www.upguard.com/blog/data-security) and [network security](https://www.upguard.com/blog/network-security) One important, often overlooked part of preventing spyware infections is [vendor risk management](https://www.upguard.com/blog/vendor-risk-management). Your internal security standards are only as good as your worst [service provider's](https://www.upguard.com/blog/third-party-vendor), just look at [what happened to Target when one of their HVAC vendors was infiltrated](https://krebsonsecurity.com/2014/02/target-hackers-broke-in-via-hvac-company/). [Third-party vendors](https://www.upguard.com/blog/third-party-vendor) introduce [third-party risk](https://www.upguard.com/blog/five-things-to-know-about-third-party-risk) and [fourth-party risk](https://www.upguard.com/blog/what-is-fourth-party-risk) that you need to monitor and where possible mitigate. Start by developing a [vendor management policy](https://www.upguard.com/blog/vendor-management-policy), [third-party cyber management framework](https://www.upguard.com/blog/third-party-risk-management-framework) and [vendor risk assessment questionnaire template](https://www.upguard.com/blog/vendor-risk-assessment-questionnaire-template). If you don't have the expertise internally, consider investing in [vendor risk management software](https://www.upguard.com/product/vendorrisk) that can help you [automate vendor risk management](https://www.upguard.com/blog/automate-vendor-risk-management), [rate your vendors against 50+ criteria](https://www.upguard.com/product/vendorrisk) and provide a [security rating](https://www.upguard.com/blog/what-are-security-ratings) so you know who your most at risk vendors are. [Information risk management](https://www.upguard.com/blog/information-risk-management) can't stop with your organization. ## How to Detect and Remove Spyware Spyware can be difficult to detect as it is designed to be deceptive and hard to find. Often the first indication of spyware infections is reduced processing power or Internet speed. For mobile spyware, unexplained data usage and reduced battery life. Anti-spyware programs exist to: * Provide real-time protection in a manner similar to antivirus software, scanning all incoming network data for spyware and blocking any potential threats * Detect and [remove spyware](https://clario.co/blog/how-to-remove-spyware-iphone-mac/) programs that are already running on the computer.  They do this by looking at the contents of the Windows registry, operating system files, installed programs and for behavioral signatures that match known spyware. These tools frequently update their database of threats to keep up with new spyware cybercriminals create.  Further, ISPs and network administrators may use firewalls and [web proxies](https://www.upguard.com/blog/proxy-server) to block access to websites known to install spyware, monitor the flow of information going to and from a networked computer and install hosts files to prevent computers from connecting to spyware-related web addresses.  Another option is to reset the computer to factory settings, this approach requires important data to be backed up and [configuration management](https://www.upguard.com/blog/5-configuration-management-boss). ## What are Examples of Spyware? * **CoolWebSearch: **A group of programs that take advantage of Internet Explorer [vulnerabilities](https://www.upguard.com/blog/vulnerability), directing traffic to advertisements, displaying pop-up ads, rewriting search results and altering the infected computer's hosts files to direct DNS lookups to different sites. * **FinFisher: **A high-end surveillance suite sold to law enforcement and intelligence agencies. FinFisher can be covertly installed on computers by [exploiting](https://www.upguard.com/blog/exploit) slow patching procedures. * **Gator: **Commonly found in file sharing software, Gator monitors victim's web activities to present them with more targeted advertisement. * **GO Keyboard: **A virtual Android keyboard app that transmits personal information to its remote servers without user consent including Google email, language, IMSI, location, network type, Android version and device model.  * **HuntBar: **Installed through an ActiveX drive-by download or by advertisements displayed by other spyware programs, adding toolbars to Internet Explorer, tracking browsing behavior, redirecting affiliate references and displaying advertisements. * **Internet Optimizer: **redirects Internet Explorer error pages to advertising. * **Look2Me: **As both a rootkit and spyware, Look2Me hides inside system-critical processes and starts up in safe mode.  * **Onavo Protect: **Used by Facebook to monetize user habits within a privacy-focused environment, criticized because the app did not prominently disclose it was owned by Facebook. * **Zango: **Transmits information to advertisers about the user's browsing patterns and alters HTTP requests for affiliated advertisements to make its creator profit. * **Zlob: **Downloads itself to a computer via an ActiveX Codec and sends search history and keystrokes to a control server. * **Zwangi: **Redirects URLs typed into the browser's address bar to a search page at www\.zwangi.com. ## How UpGuard Can Improve Your Organization's Security We're experts in [data breaches](https://www.upguard.com/blog/data-breach) and [data leaks](https://www.upguard.com/blog/data-leak), our [research](https://www.upguard.com/breaches) has been featured in the [New York Times](https://www.nytimes.com/2018/07/20/business/suppliers-data-leak-automakers.html), [Wall Street Journal](https://www.wsj.com/articles/computer-security-firm-says-voter-data-set-left-unprotected-online-1497877200), [Bloomberg](https://www.bloomberg.com/news/articles/2019-06-27/ford-td-bank-files-found-online-in-cloud-data-exposure), [Washington Post](https://www.washingtonpost.com/news/the-switch/wp/2017/12/22/you-may-not-know-much-about-the-companies-exposing-your-personal-information-but-they-know-a-lot-about-you), [Forbes](https://www.forbes.com/sites/lconstantin/2017/07/17/cloud-storage-error-exposes-over-two-million-dow-jones-customer-records), [Reuters](https://www.reuters.com/article/facebook-privacy/millions-of-facebook-records-found-on-amazon-cloud-servers-upguard-idUSL3N21L3R4) and [Techcrunch.](https://techcrunch.com/2019/09/18/russia-sorm-nokia-surveillance/) [UpGuard Vendor Risk](https://www.upguard.com/product/vendorrisk) can minimize the amount of time your organization spends managing third-party relationships by automating [vendor questionnaires](https://www.upguard.com/blog/planning-your-vendor-security-assessment-questionnaire) and continuously monitoring your vendors' [security posture](/blog/security-posture) over time while benchmarking them against their industry.  eBook A Complete Guide to Data Breaches Free resource ### A Complete Guide to Data Breaches Learn how to avoid a costly data breach with a comprehensive prevention strategy. [Download now](/resources/complete-guide-to-data-breaches) ## Related posts Learn more about the latest issues in cybersecurity. Cybersecurity #### [12 Cybersecurity Horror Stories of 2026 (No Costume Required)](/blog/cybersecurity-horror-stories-2026) A warning ignored once becomes a headline. Read more about these 12 real 2026 cybersecurity incidents, and the sign each one gave before it made the news. [](/team/revashni-moodley) [Revashni Moodley](#) October 14, 2026 Cybersecurity #### [Left Unsupervised: 10 Times Access Outlived Its Authorization](/blog/10-times-access-outlived-authorization) Access granted once shouldn’t mean access forever. Read more on how unmonitored access caused 10 of these real-life breaches and what they taught us. 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[](/team/revashni-moodley) [Revashni Moodley](#) December 1, 2025 Cybersecurity #### [Shai-Hulud's True Lesson for CISOs: A Crisis of Communication](/blog/shai-hulud-lesson-for-cisos) Shai-Hulud was driven by a communication crisis between security and engineering. Get a CISO's perspective on how to finally bridge this gap. [](/team/phil-ross) [Phil Ross](#) September 3, 2026 [All posts](/blog) Experience superior visibility and a simpler approach to cyber risk management [Get a demo](/contact-sales) [Free trial](/demo)