You don't need to install anything — just visit a compromised web-site. And it won't necessarily be a site with objectionable content — from intruders' point of view, hacking news portals is much more useful. News sites are the most visited ones on the Internet. They usually do not cause any suspicion among users or system administrators from companies which do not block access to such sites. That's why news portals are a very attractive field of operation to intruders. By Spreading malware through such sites, they can cause damage to a huge number of users and companies.