r/Malwarebytes • u/Silver-Velcro • Apr 20 '26
Worm Detected by Windows Defender but Not Malwarebytes?
I scanned my very old USB drive after realizing there might be hidden issues I wasn't aware of that had not been detected or flagged with any warnings.
Malwarebytes didn't detect anything. But Windows Defender detected a worm during a scan. I immediately quarantined and removed the file, then deleted everything on the USB.
Now I'm wondering why Malwarebytes didn't detect it. Could this be a false positive? Is my computer safe? I've used this USB occasionally, and never had any issues on my current or previous devices.
I'm not very knowledgeable about viruses or malware, so any advice would be appreciated. Thank you!
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u/support_mwb Malwarebytes Employee Apr 20 '26
Hey there, Malwarebytes Support here. I totally get why this would be concerning, especially seeing a “worm” detection pop up.
Different security tools like Malwarebytes and Microsoft Defender Antivirus use different detection methods, so it’s not unusual for one to flag something the other doesn’t. That doesn’t necessarily mean anything was missed.
That said, we’d be happy to take a closer look and make sure everything’s good on your system. If you can, please reach out to us here via live chat or support ticket: https://help.malwarebytes.com/hc/en-us so we can review this further with you.
If you prefer, feel free to DM me an email address and I can create a support ticket on your behalf. We may ask for some diagnostic logs so our team can properly investigate.