how does browser (firefox/safari) detects that website you are visiting is infected?

Question

how does browser (firefox/safari) detects that website you are visiting is infected?

Do they have a black list? or they run the URL through some Antivirus scripts? or What happens behind the scenes?

Answer 1

Each browser manufacturer maintains its own blacklist. See:

• http://www.mozilla.com/en-US/firefox/phishing-protection/
• http://www.microsoft.com/security/filters/smartscreen.aspx

Answer 2

For Firefox, implementation details can be found there: https://wiki.mozilla.org/Phishing_Protection:_Design_Documentation