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If I leave tabs open when I close Firefox then shut down PC, are the tabs available to hackers?

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I've not had this problem but someone at work warned me not to leave tabs open when I shut down because the tabs open up when the browser opens up again.....which is what I want, but she explained that the tabs open without having to re-enter passwords, so while the PC is shut down, hackers can get into the already passworded tabs. It makes no sense to me but she is adamant, saying her bank account was wiped out because she didn't close her banking tab on her browser when shutting down the computer.

I've not had this problem but someone at work warned me not to leave tabs open when I shut down because the tabs open up when the browser opens up again.....which is what I want, but she explained that the tabs open without having to re-enter passwords, so while the PC is shut down, hackers can get into the already passworded tabs. It makes no sense to me but she is adamant, saying her bank account was wiped out because she didn't close her banking tab on her browser when shutting down the computer.

Vahaolana nofidina

If your computer is turned off, it can't be hacked. Also, you can set your preferences to not save passwords if you want. But no, if your computer is turned off it can't be accessed (for obvious reasons). To get better security, you can use a master password in Firefox, or put a password on your PC so if anyone turns it back on, they have to put a password on. Use a Primary Password to protect stored logins and passwords

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Vahaolana Nofidina

If your computer is turned off, it can't be hacked. Also, you can set your preferences to not save passwords if you want. But no, if your computer is turned off it can't be accessed (for obvious reasons). To get better security, you can use a master password in Firefox, or put a password on your PC so if anyone turns it back on, they have to put a password on. Use a Primary Password to protect stored logins and passwords

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Thank you! It didn't make sense if the computer was turned off so you're answer is what I was looking for! And thank you too for the info on passwords in Firefox, very helpful!!!

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I wouldn't focus on closing or not closing a tab. I think the more important thing is to use the site's sign out link when you are finished using it. Then the bank or whoever will close your session on their side.

If you don't do this and someone restores your previous Firefox session, either at your keyboard or via remote control somehow, Firefox will send your session cookie to the site. If not too much time has passed, and your session is still active on their server, the intruder would be able to take action as you.

So, where your money or your reputation is at stake, always sign out!

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Aha.....thank you for pointing out the "sign out". I can see that by signing out at the website, you've closed that session whether the tab is still open or not. Thank you! Very helpful information.

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Note that Firefox saves session data including cookies in the sessionstore.js file. This also includes data from recently closed tabs.
You can (temporarily) switch to Private Browsing mode to prevent storing data from sites.


You can set the browser.sessionstore.privacy_level pref to 2 (never) or 1 (non-HTTPS) on the about:config page to disable saving cookies via session restore.

The browser.sessionstore.privacy_level_deferred pref is used when you do not reopen the previous session automatically via "Show my windows and tabs from last time" and uses the same values.