A post on a hacking blog claimed to show images of the site being hacked by changing parameters in the URL.

"Kaspersky is one of the leading companies in the security and antivirus market. It seems as though they are not able to secure their own data bases," said the poster. "Alter one of the parameters and you have access to EVERYTHING: users, activation codes, lists of bugs, admins, shop, etc."

"A vulnerability was detected on a subsection of the usa.kaspersky.com domain when a hacker attempted an attack on the site," the company responded in a statement over the weekend. "The site was only vulnerable for a very brief period, and upon detection of the vulnerability we immediately took action to roll back the subsection of the site and the vulnerability was eliminated within 30 minutes of detection. The vulnerability wasn’t critical and no data was compromised from the site."