With the significant prevalence of Linux web servers globally, security is often touted as a strength of the platform for such a purpose. However, a Linux based web server is only as secure as its configuration and very often many are quite vulnerable to compromise. While specific configurations vary wildly due to environments or specific use, there are various general steps that can be taken to insure basic security considerations are in place.
Many risks are possible from a compromise including using the web server into a source of malware, creating a spam-sending relay, a web or TCP proxy, or other malicious activity. The operating system and packages can be fully patched with security updates and the server can still be compromised based purely on a poor security configuration. Security of web applications first begins with configuring the server itself with strict security in mind.