It is relatively easy for our computer to be affected by infection through a Trojan. chkrootkit is a tool that can detect them. How is that? Well, by searching for the signs that they left behind.
Detection by checking the regular modified binaries files.
This is a straightforward software without a graphical interface that runs through the Linux command console. It lets you locate known rootkits by performing tests on the different binaries files they normally modify. This tool can be run in two different ways, from a recovery disk, usually using a LiveCD, or from a directory where all commands are executed.
However, there is a chance that this program will not be able to detect compromised files since the development of malware is obviously always one step ahead: state-of-the-art rootkits can detect it and even evade its detection attempts. If you are having a Trojan problem, give this tool a chance.