Hold Security had warned the media outlets that a gang of Russian hackers have gained access to 4.5 billion email addresses and passwords.

The Milwaukee based security firm estimates that 420,000 web and ftp sites, including some Fortune 500 company sites, have been compromised. But details on what specific websites were compromised were not released.

The New York Times have claimed to have had the information analyzed by a security expert not affiliated with the security firm who confirmed the authenticity of the database of stolen information. And The New York Times have also reported that some of the companies involved are aware of the situation.

Most of this information was gathered via a botnet, a collection of interconnected computers that have been infected with a virus that collects and forwards information to individuals who either sell it or use the information to send unsolicited commercial email or gain access to web sites and credit card information.

According to Hold Security the most vulnerable users are those that use a generic password on multiple sites, whose generic passwords can be used to gain access to sites that are not in the records.

They had found that out of the 4.5 billion records, only 1.2 billion had unique passwords so the firm suggest the use of more secure, unique passwords.

An individual password should not be used on multiple sites and a combination of letters (in upper and lower caps), numbers and special characters (punctuation, symbols, etc.) should be used to prevent predictability.

The use of a frequently updated anti-virus program also helps keep individual computers from being infected with viruses that keep track of the passwords used.