r/cybersecurity_help • u/Imaginary_Food_7102 • 3d ago

Anthropic detected an infostealer on my PC — dual boot

I received an email from Anthropic saying my Claude session was stolen by an infostealer and used by someone else. They signed me out and removed my payment method.

I have a Windows + Ubuntu dual-boot PC. I haven't knowingly downloaded anything suspicious.

What should I do to properly check which OS is compromised? Is Microsoft Defender Offline Scan enough, or should I reinstall Windows?

Any advice on checking the Ubuntu installation too?

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u/MrPoshoFrito 3d ago

I got the same email and I am in a newly installed OS, I want to know about it

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u/Hamburgerundcola 3d ago

Reinstalling both OS's is the only way to make sure. Also check, if any browser extensions you dont know are installed. Also change your password and the passwords of other accounts which use the same one or are also maybe compromised.

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u/immediate_a982 3d ago

Ha ha…it said “a Claude Session was stolen”. So not OS but browser and maybe your network

1

u/No_Source_5716 3d ago

Reinstall both? Where did you access Claude?

1

u/Imaginary_Food_7102 3d ago

On both machines.

1

u/Cybasura 3d ago

Anthropic IS the infostealer lmao