Could be the largest heist of its kind
- Russian hackers have stolen 1.2 billion username and password combinations.
- The digital credentials came from ~420,000 sites.
- The sites included small and well-known ones.
- The hackers make money by logging into social and email accounts and posting about fake products.
- This could be the largest theft of username and passwords.
- Security experts say users should monitor their accounts for unauthorized messages being sent out.