Nurech.BC is a rootkit. These are programs used to hide files, Windows Registry entries or processes, either their own or those of other programs.
In this way, even when a user looks for these items on a computer, they won't be able to see them.
Rootkits have been widely used for malicious ends, to camouflage other programs on computers that have previously been compromised through other means.
There are certain examples of malware that use rootkits in order to go unnoticed on the computer they have infected.
It affects productivity, preventing tasks from being carried out:
- In the affected computer:
causes system slowdowns.
- In the local network:
it generates a large amount of network activity and consumes bandwidth.
It reduces the security level of the computer:
it terminates processes belonging to security tools, such as antivirus programs and firewalls, leaving the computer defenseless against attacks from other malware.
It uses several methods in order to avoid detection by antivirus companies:
- It terminates its own execution if it detects that it is being executed in a virtual machine environment, such as VMWare or VirtualPC.
- Its code is encrypted and it is only decrypted when it is going to run. Because of this, its code is not legible through a memory dump.
Nurech.BC uses the following propagation or distribution methods:
- Exploiting vulnerabilities with the intervention of the user: exploiting vulnerabilities in file formats or applications. To exploit them successfully it needs the intervention of the user: opening files, viewing malicious web pages, reading emails, etc.
- Email: sending emails that include a copy of itself as an attachment. The computer is infected when the attachment is run.