ELF virus technology
The world of ELF virus technology shall open up many doors to you as a hacker and engineer. To begin, let's discuss what an ELF virus is. Every executable program has a control flow, also called the path of execution. The first aim of an ELF virus is to hijack the control flow so that the path of execution is temporarily altered in order to execute the parasite code. The parasite code is usually responsible for setting up hooks to hijack functions and also for copying itself (the body of the parasite code) into another program that hasn't yet been infected by the virus. Once the parasite code is done running, it usually jumps to the original entry point or the regular path of execution. This way, the virus goes unnoticed, since the host program appears to be executing normally.
Figure 4.1: Generic infection to an executable
