Suexec
From DreamHost
suexec allows Apache to run CGI programs using a user id other than that of the Apache process. Suexec significantly reduces many of the security risks associated with running CGIs. Suexec is enabled for DreamHost users, and cannot be disabled.
Because of the way suexec handles security, the directory in which your CGI scripts live must not be writable by anyone but the CGI user (chmod 755). The scripts themselves must not be writable by anyone but the CGI user, either. If they are writable, you will receive a 500 error from Apache.
