A backdoor is a type of malware that provides an attacker with remote access to a victim’s machine. Backdoors are the most commonly found type of malware, and they come in all shapes and sizes with a wide variety of capabilities. Backdoor code often implements a full set of capabilities, so when using a backdoor attackers typically don’t need to download additional malware or code.
Backdoors communicate over the Internet in numerous ways, but a common method is over port 80 using the HTTP protocol. HTTP is the most commonly used protocol for outgoing network traffic, so it offers malware the best chance to blend in with the rest of the traffic.
In Chapter 14, you will see how to analyze backdoors at the packet level, to create effective ...