According to recent blog posts published here and here by researchers from security firm Securi, Darkleech uses rogue Apache modules to inject malicious payloads into the webpages of the sites it infects and to maintain control of compromised systems. Disinfecting Web servers can prove extremely difficult since the malware takes control of the secure shell (SSH) mechanism that legitimate administrators use to make technical changes and update content to a site.
via Exclusive: Ongoing malware attack targeting Apache hijacks 20,000 sites