I found a browser extension I don't trust installed, should I worry?

Question

Someone told me that their Firefox had a strange new menu bar.

I found that it was “FindYourMaps”.

FindYourMaps is a deceptive browser toolbar that supposedly allows users to find driving directions and use various maps. Initially, this functionality may seem legitimate and useful, however, FindYourMaps is classed as a browser hijacker and a potentially unwanted program (PUP).

Source.

I uninstalled it successfully.

Should I worry about it? Could it have stolen some credentials? I used the Microsoft antivirus software to scan all the files and no threat was found.

Answer 1

The short answer: Yes, you should be worried.

There have been quite a few cases recently of malicious (or hacked) browser extensions harvesting user data, notably Catch-All last year, and the MEGA.nz extension being hijacked by hackers this year (and plenty of others, but that's enough examples to make the point).

Without knowing more, such as knowing how the extensions came to be there, and what permissions they had (see this question), it's hard to be certain exactly what the risks are. But assuming the worst is the safest option.

Malicious browser extensions are a serious risk to personal information and password security.