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1Clear out junk files and repair common Windows errors2Fix the driver behind crashes, sound loss and screen glitches3Repair Windows errors before they cause bigger problemsSpecial offer. See more information about Outbyte and uninstall instructions. Please review EULA and Privacy policy.
Slowdowns, unexpected pop-ups, browser changes, or unusual account activity can be clues that a device has malware—but none proves an infection on its own. The safest next step is to stop using the device for sensitive logins and run a current security scan. Malware can also stay hidden, so a lack of obvious symptoms does not guarantee a device is clean.
What symptoms can point to malware?
The Federal Trade Commission says these symptoms could be a sign that a device is infected with malware. Treat them as warning clues, not a diagnosis: ordinary software, network, or hardware problems can cause similar behavior.
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- Sluggish performance: A computer or phone becomes unusually slow, freezes, or crashes.
- Unexpected browser behavior: The homepage changes, searches redirect, unfamiliar toolbars or add-ons appear, or pop-up ads keep returning.
- System or security tools stop working: Repeated operating-system errors appear, or security and system tools will not open or seem to have been disabled.
- Battery or data use changes: A phone drains its battery or uses data unusually quickly. Microsoft notes that an unknown process running in the background can consume resources.
- Unfamiliar activity on your accounts: Emails or social posts appear to have been sent from your account when you did not create them.
- A demand to pay for access: Ransomware may become apparent when a message demands payment to regain access to files or a device. Do not treat payment as a reliable way to recover them.
These clues overlap with other problems, and malware may not show obvious signs. The FTC’s malware guidance and Microsoft’s scan guidance both recommend taking signs seriously without assuming they confirm infection.
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What to do if you suspect malware
- Stop entering sensitive information on the device. Avoid banking, shopping, and other sensitive logins while you assess it.
- Update reputable security software and run a scan. On supported systems, Microsoft Defender offers quick and deeper scan options; Microsoft describes Defender Offline as its most complete scan option. The available tools and steps depend on the device and operating system. Follow the instructions for your platform in Microsoft’s Defender scan guide.
- Protect important accounts from another trusted device. Change important passwords there and turn on two-factor authentication. Do not use the suspected device to reset credentials.
- Get help from a source you already trust if the scan does not resolve the issue. Contact your device maker, a technician, or a support provider you know. Do not call a number in an alarming pop-up or buy software in response to an unsolicited call or message.
- Act on possible identity theft or report a scam. If personal information may have been stolen, use IdentityTheft.gov for recovery guidance. Report malware-spreading scams or ransomware demands to the FTC at ReportFraud.ftc.gov.
How malware gets onto devices—and how to reduce the risk
Microsoft identifies malicious email attachments, unsafe or bundled downloads, and compromised webpages that exploit software vulnerabilities as common infection routes. These precautions reduce exposure to those routes:
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See Microsoft’s overview of how malware can infect a PC and the FTC’s advice on protection and detection.
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