Spyware quietly collects what people type, browse and store, then sends it to an attacker. For organizations, the damage rarely stops at one device: infostealers lift passwords and session cookies from browser profiles, and that stolen data is traded as access to company systems. This guide covers how spyware works, how to spot and remove it, and why multi-factor authentication alone does not close the gap.
Key takeaways
- Spyware collects data in the background, and infostealers are the type that target passwords, browser data and session cookies.
- Multi-factor authentication is enforced at login, so a stolen session cookie lets an attacker skip the second factor entirely.
- Delivery stays human: a cracked application, a fake browser update or a pasted command is usually how an infostealer gets in.
- After an infection, changing passwords is not enough. Sign out of active sessions so stolen cookies stop working.
- Training that tests what employees run and click is the control that still works when MFA is bypassed.
What is Spyware?
Spyware is a type of malicious software designed to secretly monitor and collect information about a person or organization's activities without their consent. Once installed, spyware can track browsing habits, capture sensitive data such as passwords, credit card details, and even record audio or video from a device.
How Does Spyware Work?
Spyware infiltrates a system by disguising itself within legitimate software, emails, or downloads. Once activated, it operates in the background, collecting personal information and transmitting it to cybercriminals. Common types of spyware include:
- Keyloggers: Record every keystroke to steal passwords and other sensitive information.
- Infostealers: Harvest saved passwords, browser data and session cookies from a device, then sell or reuse them to access accounts.
- Adware: Tracks your browsing habits to show unwanted ads or redirect your browser.
- Trojan Horses: Hide spyware within seemingly harmless programs to gain access to your data.
- System Monitors: Capture detailed data, including chat logs, browser history, and more.
- Stalkerware: Installed on a phone or computer to track a person's location, messages and activity.
How to Identify Spyware
Spyware often goes undetected for long periods because it's designed to be stealthy. However, there are several signs that could indicate your device is infected:
- Sluggish performance: Spyware consumes system resources, making your device slow.
- Unexpected pop-ups: Frequent, random pop-ups could be a sign of adware spyware.
- Browser redirects: If your browser frequently redirects you to unfamiliar websites, spyware may be at work.
- Increased data usage: Unexplained spikes in data consumption might indicate that spyware is sending information in the background.
- Battery drain: Spyware runs continuously, potentially leading to quicker battery drain on mobile devices.
Tools to Detect Spyware
You can use dedicated spyware detection tools to scan for infections. Some of the most trusted tools include:
- Malwarebytes: A powerful anti-malware tool with a specific focus on removing spyware.
- Spybot Search & Destroy: Detects and removes spyware and adware from your system.
- Avast Antivirus: Offers real-time protection against spyware, phishing attacks, and malware.
How to Remove Spyware
If you suspect your device is infected with spyware, take the following steps to remove it:
1. Disconnect from the Internet
Isolate your device from the internet to prevent the spyware from transmitting more information to attackers. This can stop further data leakage while you address the issue.
2. Run an Anti-Spyware Scan
Use trusted anti-spyware software to perform a complete scan of your device. Tools like Malwarebytes or Norton Power Eraser can identify and remove spyware effectively. Make sure to update the software first to ensure it can detect the latest threats.
3. Remove Suspicious Programs
Check your installed programs list for any unfamiliar or recently installed software. On Windows, this can be done via "Control Panel > Programs > Uninstall a Program." On macOS, look in the "Applications" folder. Uninstall any suspicious applications you don't recognize.
4. Reset Your Browser Settings
Spyware often modifies browser settings to track your online activities. Reset your browser to its default settings to remove any extensions or configurations that might be compromised. In Chrome, for example, go to “Settings > Advanced > Reset and Clean Up.”
5. Change All Passwords
After you have removed spyware, change all your passwords, especially for sensitive accounts like banking, email, and social media. This ensures that any credentials compromised by spyware will no longer be valid. Also sign out of every active session and device: a stolen session cookie can stay valid after a password change, and signing out revokes it.
6. Update Your Operating System and Software
Spyware often exploits vulnerabilities in outdated systems and applications. Make sure your operating system, browsers, and other software are up-to-date to reduce the risk of future infections.
Why Stolen Cookies Defeat Multi-Factor Authentication
The corporate consequence of an infostealer is rarely the password. It is the session cookie sitting next to it in the browser profile.
Multi-factor authentication is enforced at login. Once a valid session cookie exists, the server treats the client as already authenticated, so an attacker replaying that cookie is never challenged for a second factor. The login looks legitimate because, technically, it is.
This is why "we have MFA everywhere" is an incomplete answer to credential theft, and why infostealer logs are traded as access rather than as passwords. We cover the mechanics in stealing web session cookies, part of our MITRE F3 series. The same replay logic applies to adversary-in-the-middle attacks, where a proxy captures the session as the victim logs in.
The delivery side stays human. An infostealer arrives because somebody ran something: a cracked application, a fake browser update, or a command pasted at the request of a caller claiming to be IT support. Microsoft reports that last pattern, ClickFix, as the leading initial access technique at 47%.
See how phishing simulation works →
Preventing Spyware Infections
While removing spyware is crucial, preventing it from ever infecting your system is even better. Here are best practices to keep spyware at bay:
1. Use Trusted Anti-Malware Software
Install reputable anti-malware software and enable real-time protection. Regularly update the software so it can defend against the latest threats.
2. Be Cautious with Downloads
Only download software from trusted sources or official app stores. Avoid clicking on pop-up ads or downloading attachments from unknown emails, as they are common spyware distribution methods.
3. Avoid Public Wi-Fi Without Protection
Using public Wi-Fi can expose your device to cybercriminals. If you must connect to a public network, use a virtual private network (VPN) to encrypt your data and prevent spyware infections.
4. Keep Your Operating System Updated
Ensure your operating system, browsers, and applications are updated to their latest versions. Security patches fix vulnerabilities that spyware may exploit.
5. Enable Two-Factor Authentication (2FA)
Whenever possible, enable two-factor authentication (2FA), or multi-factor authentication (MFA), on your accounts. It stops an attacker who only has a stolen password. It does not stop an infostealer that takes an active session cookie, because that session is already authenticated. Treat 2FA as one layer and keep the habits above, especially careful downloads and regular updates.
Conclusion
Spyware is a hidden threat that can compromise your privacy, steal sensitive data, and affect device performance. Identifying the signs of infection, using effective removal tools, and adopting best security practices are essential steps to protect yourself from this dangerous malware. Stay vigilant and proactive to keep your devices secure and your personal information private.
MFA does not stop a stolen session
Infostealers take the cookie, not just the password, and the replayed session never triggers a second factor. The control that still works is whether your people run the thing in the first place. Test it with phishing simulation, and see how the session cookie theft behind it works.