Process memory viruses and rootkits – remote code injection techniques

Up until now, we've covered the fundamentals of infecting ELF binaries with parasite code, which is enough to keep you busy for at least several months of coding and experimentation. This chapter would not be complete, though, without a thorough discussion of infecting process memory. As we've learned, a program in memory is not much different than it is on disk, and we can access and manipulate a running program with the ptrace system call, as shown in Chapter 3, Linux Process Tracing. Process infections are a lot more stealthy than binary infections, since they don't modify anything on disk. Therefore, process memory infections are usually an attempt at defeating forensic analysis. All of the ELF infection points that we just discussed are relevant to process infection, although injecting actual parasite code is done differently than it is with an ELF binary. Since it is in memory, we must get the parasite code into...