Microsoft has issued a warning that a new piece of malware called JS/Febipos.A is making its rounds disguising itself as a Chrome extension and Firefox add-on. The malware monitors whether your computer is logged into a Facebook account, if your computer has an account logged in it can perform a variety of actions such as, commenting on a post, liking a page, sharing, posting, joining a group, chatting with the your friends, and posting messages on your page with links to other pages.
If you notice odd behavior coming from your facebook account (comments and likes you didn’t make etc.) It would be advisable to run a security scan with your anti-virus software (or use one of the security tools mentioned below). Then reset your password.