kguske writes:  

From Netcraft:

Hackers have compromised the download server for the open source PostNuke content management system, redirecting users to malicious code in place of the .zip download of the PostNuke program. The hacked code was distributed for more than 32 hours before PostNuke site maintainers addressed the security breach.PostNuke users who installed a zip archive downloaded between 11:50 pm Sunday night and 8:30 a.m. today face a grim scenario. According to a statement on the PostNuke site, all data submitted during the installation - including the server name, database credentials, admin name and password - were likely sent to the hackers. In addition, "in one file there was code allowing a malicious user to execute any shell command on the web server."

Either scenario would allow the attackers to gain control of the site where PostNuke was installed. The tar.gz download file was not affected. The tar format is traditionally used by Unix and Linux, while Zip is the leading Windows archive format.

The PostNuke team is advising users who may have installed the compromised files to reinstall the code, and immediately change their database details, including username, password and the name of the database if possible.

PostNuke is a development fork of the PHPNuke content management system. Both programs are open source projects using PHP and a MySQL database that are widely used but have a history of security issues. The attacker in Sunday night's attack used a security hole in pafiledb, a download management app that is not part of the official PostNuke software, but was used to maintain the PostNuke site. The flaw in the .zip archive was detected by a user and posted to the PostNuke forum Monday evening.