Hi, and why would you consider malware, not a malware issue and as a browser issue. Your in control of where you go and what you download and install and your own security software to prevent such things.

If not fixed your malware issue please give your self a scan :

• https://www.malwarebytes.com/mac/
• https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-caused-malware

Save your Report and google each before deleting anything as do not want to delete something you need, If need help :

• https://forums.malwarebytes.com/topic/9573-im-infected-what-do-i-do-now/

Please let us know if this solved your issue or if need further assistance.

Have you gone to your computer chip maker and looked for a patch or a bios flash ?

• https://www.theinquirer.net/inquirer/news/3023893/opera-mozilla-vivaldi-and-more-rush-to-patch-spectre-and-meltdown-security-holes
• https://money.cnn.com/2018/01/04/technology/spectre-meltdown-cpu-flaws-explainer/index.html
• https://www.howtogeek.com/338801/how-to-check-if-your-pc-is-protected-against-meltdown-and-spectre/

ignore the above two posts and much of it was for Windows in mind.

tuomoks said

Is this possible "When you were busy watching videos, your web browser began functioning as a RDP (Remote Desktop Protocol) having a key logger which provided me accessibility to your display and your web camera controls. After that, the malware obtained all your contacts from messenger, fb, as well as email. "-

So you got a email that had this wording?

This is a a variation of the blackmail email SCAMS. https://www.reddit.com/r/Scams/comments/8gsjba/the_blackmail_email_scam/

https://www.kshb.com/money/consumer/dont-waste-your-money/scary-porn-blackmail-scam-knows-your-password

No flaw in Firefox or due to any malware.

As I thought - there is no sign of any malware or virus, so they have gotten one password (not used in this machine) from somewhere else. Outbound connection / traffic logs don't have any anomalies. So - some my old connections, etc, nothing very important.

But the question stays - just curious - can Firefox be infected even not allowing changes, not installing anything, just browsing, i.e. is some function from outside allowed to do that? Shouldn't it ask a permission even if it is allowed for some (strange) reason?