Hackers (read as cracker) attacking on unpatched versions of the Mambo content management system that can be used to build botnets for use in phishing scams and distributed denial of service (DDoS) attacks.
They are using PHP-based CMS mass-exploitation and other vulnerabilities in open source CMS applications. If you are in server, collocation businesses then watch out all these attacks.
Update Mambo as soon as possible. More information available at following sites: