Trojan Programs - Backdoors

Today backdoors are the most dangerous type of Trojans and the most widespread. These Trojans are remote administration utilities that open infected machines to external control via a LAN or the Internet. They function in the same way as legal remote administration programs used by system administrators. This makes them difficult to detect.
The only difference between a legal administration tool and a backdoor is that backdoors are installed and launched without the knowledge or consent of the user of the victim machine. Once the backdoor is launched, it monitors the local system without the user's knowledge; often the backdoor will not be visible in the log of active programs.
Once a remote administration utilitiy has been successfully installed and launched, the victim machine is wide open. Backdoor functions can include:
- Sending/ receiving files
- Launching/ deleting files
- Executing files
- Displaying notification
- Deleting data
- Rebooting the machine
In other words, backdoors are used by virus writers to detect and download confidential information, execute malicious code, destroy data, include the machine in bot networks and so forth. In short, backdoors combine the functionality of most other types of Trojans in one package.
Backdoors have one especially dangerous sub-class: variants that can propagate like worms. The only difference is that worms are programmed to propagate constantly, whereas these "mobile" backdoors spread only after a specific command from the "master".Русская классика,