What Is Spyware?

Spyware is a deceptive software that has evolved in sophistication and prevalence, prompting concerns from everyday individuals to large-scale corporations. To protect ourselves and our data effectively, we must first understand what spyware is and how it operates.

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Spyware Definition

Spyware is a specific malicious software (malware) installed on a computing device without the end user’s awareness. As the name implies, “spyware” derives from the software’s primary function–to “spy” on the user. It’s designed to discreetly invade the device, steal sensitive information and internet usage data, and relay it to threat actors, advertisers, data firms, or other special interest parties.

Spyware is one of the most common threats to internet users and can make its way onto a device without the end user’s knowledge via an app install package, file attachment, or malicious website. Certain characteristics define spyware against other types of cyber-attacks, including:

  • Steals Sensitive Information: Spyware monitors internet activity, tracks login credentials, and spies on sensitive information. The primary goal of spyware is usually to obtain credit card numbers, banking information, and passwords.
  • Difficult to Detect: Spyware can be difficult to detect, as its presence is often hidden from the user. It can exist as an application that runs as soon as the device starts up and continues to run in the background.
  • Slows Down Devices: Spyware can slow down devices by stealing random access memory and processor power and generating infinite pop-up ads. This slows down the web browser and affects device performance.
  • Intentional Spyware Installation: Some spyware, such as keyloggers, may be installed by the owner of a shared, corporate, or public computer intentionally to monitor users.
  • Spyware is Preventable: Using anti-spyware software, keeping software up to date, and avoiding suspicious websites and downloads can prevent spyware.

Spyware represents a significant breach of privacy with consequences ranging from targeted advertising based on one’s web habits to more severe threats like identity theft, financial loss, or the unauthorised dissemination of personal or proprietary information.

How Spyware Works

Understanding the mechanics of spyware provides insight into its silent yet invasive nature and equips users and organisations with knowledge of how to combat it.

Mechanics of Operation

1. Infiltration: The initial step involves gaining access to the user’s device. Spyware can be:

  • Bundled with free software where an unknowing user thinks they’re only downloading a harmless application.
  • Hidden within malicious links or advertisements that, when clicked, initiate an automatic download.
  • Disguised as a legitimate update or software installation package.
  • Delivered through exploit kits, which identify vulnerabilities in a system’s software and use them as entry points.

2. Stealth Mode: Once inside a system, most spyware operates silently. It’s designed to:

  • Avoid Detection: Disguises itself with non-threatening file names or mimics legitimate processes.
  • Bypass Security Measures: It may deactivate firewalls, antivirus software, or other security features to ensure its uninterrupted operation.
  • Autostart Capabilities: Many spyware programmes embed themselves within the system’s startup processes, ensuring they activate every time the device is powered on.

3. Data Collection: After infiltration, spyware’s primary goal is information harvesting. It employs various techniques:

  • Tracking Cookies: These monitor and record web browsing activities, including sites visited, search queries, and clicked advertisements.
  • Keyloggers: By recording keystrokes, spyware can capture passwords, credit card details, and other sensitive input.
  • System Scanners: Some spyware scans system files, directories, and documents for specific information.
  • Screenshots: Advanced spyware may periodically take screenshots, capturing real-time user activity.

4. Data Transmission: Collected data is sent to a remote server controlled by the spyware’s author or operator. Typically, this transmission is done:

  • Periodically: The spyware may package and send the collected data at regular intervals.
  • Stealthily: Data transfer is usually encrypted and transmitted in small packets to avoid detection.

Implications of Spyware Activities

The implications of spyware are numerous and can have a detrimental impact on both individual users and organisations. They include:

  • Privacy Breach: The most immediate implication is the blatant invasion of the user’s personal and digital privacy.
  • Identity Theft: With the gathered information, malicious actors can impersonate users, leading to fraud or unauthorised transactions.
  • Financial Loss: Captured banking details or credit card information can lead to unauthorised purchases and significant financial losses.
  • System Degradation: Spyware often consumes system resources, leading to decreased performance, slower speeds, and frequent crashes.
  • Targeted Attacks: Cybercriminals use harvested information to craft personalised phishing attacks or scams.
  • Propaganda and Manipulation: Based on browsing habits, cybercriminals feed misleading information or targeted ads to users that shape their digital experiences or even real-world perceptions.
  • Data Loss: Some spyware variants can alter or delete files, potentially causing irreversible loss of crucial data.
  • Bandwidth Consumption: Regular data transmission to remote servers can eat up bandwidth, slowing internet speeds and increasing data usage costs.
  • Legal Implications: Unauthorised access and data theft can have legal ramifications for victims, especially if sensitive data is leaked.


Spyware’s covert nature underscores the importance of regular system checks, updates, and an understanding of online safety practices. The repercussions of spyware infections extend beyond digital boundaries, making vigilance essential in our increasingly online lives.

How Spyware Infects Devices

Spyware’s insidious nature lies in its capacity to infiltrate devices without detection. Its creators employ a myriad of tactics to ensure successful deployment and persistence in targeted systems. Here are some of the most common methods cybercriminals use to deploy spyware.

Bundled Software and Freeware

Many free applications, especially those from unverified sources, come bundled with spyware. Additional unwanted programmes might be included during the installation process. These bundled installations are often presented as “recommended” settings, and users must opt for a custom installation to deselect unwanted programmes.

Malicious Downloads

Cybercriminals embed spyware in files available for download on the internet. This includes software, media files, or documents that appear legitimate. Pop-up ads or websites disguised as legitimate sources can trick users into downloading these files.

Drive-by Downloads

These are initiated without the user’s explicit consent. Merely visiting a compromised website or clicking on a deceptive pop-up can trigger an automatic spyware download. Exploit kits are key to this method by scanning the user’s device for vulnerabilities and using them as points of entry.

Phishing Emails and Attachments

Cybercriminals send emails disguised as legitimate communications, often imitating banks, service providers, or even colleagues. These socially engineered emails contain malicious attachments or links that, when clicked, install spyware on the device.

Malicious Mobile Apps

With the proliferation of smartphones, spyware targeting mobile devices has surged. Such spyware often disguises itself as a useful app on app stores. Once downloaded, these apps request extensive permissions, giving them broad access to the device’s data.

Browser Hijackers

This form of spyware modifies browser settings without the user’s knowledge. It can change the default search engine and homepage or add unwanted toolbars. While the primary purpose is to redirect web traffic or display ads, browser hijackers can also facilitate other spyware installations.

Vulnerabilities in Software or Operating Systems

Outdated software or operating system (OS) versions may have known vulnerabilities that cybercriminals exploit to push spyware installations. That’s one reason why regular software and OS updates, which often come with security patches, are crucial.

Network Propagation

In environments with interconnected devices, like corporate networks or shared Wi-Fi, once one device is infected, spyware can spread to other devices within the network.

Understanding these tactics is the first step in preventing spyware infections. It reinforces the importance of cautious online behaviours, regular software updates, and using trusted security solutions to detect and remove potential threats.

Types of Spyware

Spyware is a broad term that encompasses various malicious programmes designed to snoop on users and extract personal data. Different types of spyware are distinguished based on their methods of operation, the type of information they target, and their deployment tactics. Some of the most common types of spyware include:

Trojan Horses (Trojans)

Trojans, named after the famous Greek myth, disguise themselves as legitimate software. Unlike computer viruses, trojans don’t replicate themselves but pave the way for other malware, including spyware, to be installed on the victim’s device. Once activated, a trojan can grant cybercriminals remote access to a user’s device, allowing for data theft, system control, and additional malware installation.


Adware is software that displays unwanted advertisements, usually pop-ups, on a user’s device. While not always malicious, adware becomes spyware when it collects data without consent to tailor ads based on user behaviour. Beyond the nuisance of intrusive ads, adware redirects users to malicious websites, consumes system resources, and compromises user privacy by tracking browsing habits.

Tracking Cookies

Cookies are small files that websites place on users’ devices to remember preferences or track visits. Tracking cookies, however, monitor user activity across various sites without clear disclosure or consent. They compile detailed profiles of users’ browsing habits, preferences, and interests. This data is used to target ads more effectively or sell to third parties.

Password Stealers

As the name suggests, password stealers retrieve passwords from a victim’s device. They can target stored passwords in browsers or other password-protected applications. The captured passwords grant attackers access to personal accounts like email, social media, or banking, leading to identity theft, financial losses, or unauthorised use of services.


Keyloggers record every keystroke made on a device. They can capture passwords, messages, credit card numbers, and other sensitive information entered via a keyboard. This real-time data recording provides cybercriminals with a wealth of information, including login credentials, personal conversations, and confidential data.

System Monitors

These monitor computer activity in its entirety. They can capture data ranging from opened applications and visited websites to real-time screen recordings. System monitors provide attackers with a comprehensive view of a user’s digital activities, making it easy to harvest sensitive information or even intellectual property.


Rootkits obtain administrative access (root or privileged access) to a user’s device. Once installed, they hide their presence and the presence of other malware. With deep system access, rootkits can alter system settings, evade detection, and grant cybercriminals complete control over the compromised device.

These are just some of the primary types of spyware. Given the ever-evolving nature of cyber threats, new variants and techniques continually emerge.

How to Recognise Spyware Threats

Early recognition of spyware threats can prevent data breaches and ensure device security. Watch out for the following telltale signs that may indicate the presence of spyware:

  • Unexpected System Behaviour: If your device acts erratically, crashes frequently, or restarts without prompting, spyware might be the culprit.
  • Excessive Pop-up Ads: A sudden surge in unwanted pop-up advertisements, especially ones unrelated to your browsing habits, is a common sign of adware.
  • Unauthorised Charges: Check bank and credit card statements regularly. Unknown transactions might be a result of stolen financial data.
  • Browser Alerts: If your browser warns about a website’s security certificate or redirects you to unfamiliar websites, this could indicate browser hijacking.
  • Changed Settings: Unexpected alterations in your device settings, browser homepage, or default search engine may be the handiwork of spyware.
  • Sluggish Performance: A noticeable slowdown in device performance or internet speeds, not attributed to hardware ageing or network issues, might suggest spyware activity.
  • Battery Drain: Rapid battery consumption on mobile devices can sometimes result from active spyware running in the background.
  • Data Usage Spike: An unexplained surge in data usage might be due to spyware transmitting collected information to remote servers.
  • Disabled Security Software: If your antivirus or firewall is deactivated unexpectedly or refuses to start, spyware might be attempting to avoid detection.
  • Suspicious Emails or Messages: Receiving unexpected password reset emails or notifications from unfamiliar accounts can signal an identity breach.


Recognising the signs of spyware and adhering to best practices is essential in maintaining a secure digital environment. Stay proactive, remain vigilant, and prioritise your digital safety.

How to Protect Against Spyware

Ensuring the safety of both mobile phones and computers from spyware threats requires a combination of proactive measures, best practices, and informed choices. Here are protection tips tailored for these devices:

For Computers:

  • Install Reputable Antivirus: Choose a well-reviewed antivirus software that provides real-time protection against malware, including spyware.
  • Regular Updates: Always keep your operating system, software, and drivers updated. Patches and updates often address security vulnerabilities.
  • Firewall Activation: Use a built-in or third-party firewall to monitor and filter data transfers, blocking potential threats.
  • Avoid Suspicious Downloads: Be wary of free software, especially from unverified sources, as they might come bundled with spyware.
  • Secure Browsing: Use browser extensions that block pop-ups and tracking cookies. Also, browse in incognito or private mode to reduce tracking.
  • Email Caution: Never open attachments or click links from unknown or suspicious sources. They might be phishing attempts laced with spyware.
  • Multifactor Authentication: Activate multifactor authentication for your accounts, adding an extra layer of security.
  • Educate and Train: Security awareness is key. Ensure that you and other computer users know about the risks of spyware and the best ways to avoid it.


For Mobile Phones:

  • Trusted App Sources: Only download apps from official app stores like Google Play for Android and App Store for iOS.
  • App Permissions: Regularly review and limit app permissions. If an app requests excessive permissions that aren’t necessary for its function, it’s a red flag.
  • Regular Device Scans: Install a reputable mobile security app that scans for malware and spyware. Run regular scans and keep the app updated.
  • Update Regularly: Ensure your phone’s operating system and apps are updated. Manufacturers often release security patches to address vulnerabilities.
  • Beware of Public Wi-Fi: Avoid accessing sensitive information when connected to public Wi-Fi networks. If necessary, use a VPN to encrypt your data.
  • Device Encryption: Use built-in options to encrypt your device, making it harder for spyware to access data.
  • Remote Wipe: Set up the ability to remotely wipe your phone’s data in case it’s lost or stolen.
  • Suspicious Links and SMS: Just like with computers, avoid clicking on links sent via SMS or email unless you’re sure of the sender’s authenticity.


Remember, the best defence against spyware combines technological safeguards and informed choices. Stay updated, be cautious, and prioritise security in all digital interactions.

Examples of Spyware

The following examples of spyware highlight how attackers use it to infiltrate businesses, compromise privacy, and steal sensitive information.

  • Zeus: Zeus is a notorious spyware that targeted financial institutions. Zeus, or Zbot malware, infected computers and stole sensitive information, such as login credentials and banking details, allowing cybercriminals to carry out fraudulent transactions.
  • WebcamGate: In Philadelphia, schools used LANrev’s TheftTrack programme to spy on students by remotely activating webcams on school-issued laptops students used at home. This incident raised concerns about privacy and surveillance.
  • Stuxnet: Stuxnet was a highly sophisticated spyware attack discovered in 2010. This attack targeted industrial control systems, specifically those used in Iran’s nuclear programme. Stuxnet sabotaged centrifuges by altering their operation, causing physical damage.
  • ShadowPad: ShadowPad is a spyware attack that targeted software supply chains. It compromised a software vendor’s update mechanism, allowing the attackers to distribute malicious updates to unsuspecting users. This attack affected numerous organisations across various industries.

These real-world spyware examples underscore the importance of implementing robust security measures and staying vigilant against the evolving nature of these cyber threats.

How Proofpoint Can Help

An industry-leading cybersecurity company with a global footprint in protecting organisations, their assets, and their people, Proofpoint offers several solutions that protect against spyware, including:

  • Proofpoint Email Protection: This solution helps secure and control inbound and outbound emails and detects and blocks both malicious and malware-less email threats.
  • Proofpoint Targeted Attack Protection (TAP): This solution detects, analyses, and blocks advanced threats before they reach the inbox, including ransomware and other advanced email threats delivered through malicious attachments and URLs.
  • Proofpoint Identity Threat Detection & Response: This solution helps discover and prioritise identity vulnerabilities, automatically purge risks from endpoints and servers, and deploy deception for failsafe intruder detection.
  • Proofpoint Email Security: This solution covers the entire spectrum of known email threats, including commodity threats such as spam and known malware.

Proofpoint also offers security awareness training to educate teams on detecting, avoiding, and minimising persistent spyware threats and other social engineering tactics. Together, these solutions provide a high level of security and reliability, protecting against cyber threats and ensuring that digital signatures remain secure and protected. For more information, contact Proofpoint.

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