Have you noticed unexpected pop-ups, sudden slowdowns, or strange logins that you can’t explain? These warning signs often point to a Trojan horse infection—one of the most common and dangerous forms of malware because it hides behind software that looks trustworthy.
A Trojan rarely comes alone. It can silently install spyware, open a remote backdoor, steal credentials, or pull in additional malware like ransomware. That’s why removing it properly isn’t just about running a scan—it’s about eliminating the root cause and preventing reinfection.
This guide explains how to get rid of a Trojan horse, how to confirm infection, and how to secure your device or organization afterward.
What is a Trojan Horse?
A Trojan horse is malware disguised as something useful or harmless, such as:
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Free software downloads
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Browser extensions
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“Security” tools or system optimizers
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Email attachments
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Cracked or pirated apps
Once installed, the hidden code runs quietly in the background. Unlike classic viruses, Trojans usually don’t replicate automatically. Instead, they rely on tricking people into installing them.
What Can a Trojan Do?
Depending on the type, a Trojan may:
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Steal passwords, saved logins, and cookies
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Install spyware, keyloggers, or ransomware
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Provide remote access to attackers
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Disable antivirus or security tools
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Monitor browser activity and redirect traffic
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Download additional malware without warning
For businesses, even a single Trojan infection can lead to compromised accounts, stolen data, and broader network intrusion.
Signs You Might Have a Trojan Virus
Trojans often mimic normal system behavior, which is why they can remain undetected for long periods. However, these symptoms commonly appear:
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Slow performance and high CPU usage
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Frequent crashes, freezes, or unusual error messages
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Browser redirects, new extensions, or altered homepage settings
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Unknown programs installed without permission
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Antivirus disabled unexpectedly
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Strange network activity while the device is idle
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Suspicious admin accounts or unfamiliar login alerts
In business environments, your EDR or firewall logs may show unusual outbound connections or repeated authentication attempts.
How Trojans Usually Infect Devices
Most Trojans rely on common delivery methods:
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Malicious email links and attachments
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Fake download buttons on untrusted sites
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Free software bundles (often with hidden installers)
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“Cracked” programs and pirated tools
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Malvertising (infected ads)
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SEO poisoning (fake pages ranking in search results)
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USB devices or shared infected files
Once the Trojan runs, it may create persistence so it starts again every time the system reboots.
How to Remove a Trojan Horse (Windows: Step-by-Step)
A proper removal process should accomplish two goals:
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Remove the malware payload
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Remove persistence methods so it doesn’t return
Follow these steps carefully.
Step 1: Disconnect the Infected Device From the Internet
Before you scan or troubleshoot:
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Turn off Wi-Fi or unplug Ethernet
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If it’s a work device, isolate it from the company network
This reduces the chance of:
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data theft
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remote attacker control
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downloading additional malware
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spreading infection across systems
Step 2: Restart in Safe Mode (Optional but Helpful)
Safe Mode reduces background processes, preventing many Trojans from running actively.
How (high-level):
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Settings → Recovery → Advanced startup → Restart
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Troubleshoot → Advanced Options → Startup Settings
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Select Safe Mode
If you can’t access Safe Mode due to malware interference, proceed to offline scanning.
Step 3: Run a Full Antivirus Scan
Start with your installed security tool or Microsoft Defender.
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Open Windows Security
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Virus & threat protection → Scan options
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Select Full scan
After the scan:
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Remove or quarantine detected items
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Restart
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Scan again to confirm cleanup
Step 4: Run an Offline Scan for Persistent Trojans
Some Trojans hide when Windows is running. Offline scanning is effective because it runs before the OS fully loads.
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Windows Security → Virus & threat protection
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Scan options → Offline scan
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Restart and allow the scan to finish
If the Trojan remains after a full scan, offline scanning is one of the best next steps.
Step 5: Remove Trojan Persistence (Critical)
Even if the Trojan file is removed, it may have created mechanisms to restart itself.
Check Startup Programs
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Task Manager → Startup tab
Disable suspicious items (unknown publisher, random names, odd file locations)
Check Scheduled Tasks
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Open Task Scheduler
Look for tasks running strange executables, especially in: -
AppData
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Temp folders
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hidden directories
Check Installed Programs
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Control Panel → Programs
Remove anything you don’t recognize
Check Services
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Run
services.msc
Look for unknown services with odd descriptions and random names
Step 6: Remove Malicious Browser Extensions and Reset Settings
Trojans often hijack browsers by installing malicious extensions or changing settings.
Do this:
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Remove unknown extensions from Chrome/Edge/Firefox
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Reset browser settings to default
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Clear browsing data
Optional additional step:
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Open Command Prompt as Admin and run:
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ipconfig /flushdns
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This helps remove cached redirects and poisoned DNS records.
Step 7: Update Windows and Applications
Trojans commonly exploit vulnerabilities in outdated software.
Update:
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Windows
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browsers
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PDF readers
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Java
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Office and plugins
Remove unused programs—especially those from unofficial sources.
Step 8: Change Passwords After Cleanup
Many Trojans steal credentials. Changing passwords too early (while infected) is risky because the Trojan can capture the new password.
After the device is clean:
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Change passwords from a clean device
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Enable multi-factor authentication (MFA)
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Rotate important business credentials (admin, VPN, email, cloud apps)
How to Remove Trojan Virus on Windows 10
For Windows 10, focus on these steps:
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Update antivirus definitions
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Run full scan
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Run offline scan if symptoms remain
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Remove suspicious startup apps and scheduled tasks
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Reset browsers and remove unknown extensions
How to Remove Trojan Virus From Windows 11
Windows 11 follows the same process, but prioritize:
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Full scan
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Offline scan if the Trojan reappears
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Startup and scheduled task cleanup
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Browser extension review
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Apply Windows updates immediately
How to Get Rid of a Trojan Horse Virus on a Phone
Many users ask: “What is a Trojan virus on a phone?”
It is typically a malicious app that looks legitimate but secretly steals data, monitors activity, or controls device functions.
Android: Trojan Removal Steps
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Turn on Airplane mode
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Go to Settings → Apps and uninstall suspicious apps
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Remove unknown Device Admin Apps (Settings → Security)
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Scan using a reputable mobile security app
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Update Android OS
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Change passwords from a clean device
If the Trojan won’t uninstall:
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boot into Safe Mode
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remove it
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if it persists, back up important data and factory reset
iPhone: What to Do
Trojan infections on iPhones are less common but phishing and account compromise still happen.
Steps:
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Remove unknown profiles (Settings → General → VPN & Device Management)
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Update iOS
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Change Apple ID password and enable MFA
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If compromise is suspected, back up and reset the device
How to Stop a Trojan Virus From Coming Back
Removal is not enough if the original infection method remains.
Prevention checklist:
Avoid risky downloads
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Do not use pirated software
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Avoid “free tools” from unknown sources
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Be careful with browser extensions
Improve email safety
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avoid unknown attachments
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verify sender identity
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don’t click shortened links
Keep systems patched
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update Windows, browsers, and third-party software
Use MFA everywhere
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email
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cloud tools
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admin accounts
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banking accounts
Use endpoint protection with behavior detection
Traditional scanning is not always enough, especially for new Trojan variants.
Action Plan for IT Managers, CEOs, and Founders
If you manage an organization, the bigger risk isn’t one infected device—it’s what happens next.
Recommended approach:
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isolate the endpoint immediately
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check all endpoints for similar indicators
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monitor outbound traffic and abnormal authentication events
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rotate credentials after cleanup
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strengthen email filtering and DNS protections
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conduct user awareness training
A Trojan infection is often the first step before a wider security incident, so respond early and thoroughly.
1) How do I check if I have a Trojan virus?
Watch for unusual system behavior, unknown apps, disabled security tools, browser hijacking, and run a full scan plus offline scan.
2) Can antivirus remove a Trojan horse?
Yes, many Trojans can be removed with a full scan. Persistent Trojans often require offline scanning and manual cleanup of startup items.
3) Should I factory reset my PC to remove a Trojan?
If the Trojan returns after cleanup or you suspect deep system tampering, a full reinstall or reset can be the safest approach—especially for business systems.
4) What is a Trojan virus on a phone?
It is typically a malicious app pretending to be legitimate. It may steal data, intercept messages, or grant attackers control.
5) Can a Trojan steal passwords?
Yes. Many Trojans are designed specifically to steal credentials, cookies, and banking information. MFA and password rotation are essential after cleanup.
Conclusion
Trojans are dangerous because they blend into everyday downloads and quietly create long-term access for attackers. The safest way to remove one is a complete process: isolate, scan (including offline), remove persistence, update software, and change passwords only after the device is clean.
If you need professional support for cleaning infected devices, validating security posture, or protecting your organization, contact here:
https://scanoncomputer.com/contact/