Dialer.LIU is a dialer type malware. Dialers usually try to establish phone connections with high rate numbers, significantly increasing the phone bill of the affected user.
Dialer.LIU affects computers that use a modem to connect to the Internet, as the virus modifies the Dial-up network access settings. It changes the telephone number provided by the ISP (Internet Service Provider), which is a local-rate number, to a high-rate number.
Dialer.LIU accesses several websites to download files, which it then runs. These can be any type of file, although they are normally malware.
It uses stealth techniques to avoid being detected by the user:
- It uses techniques included in its code to hide itself while it is active.
- It modifies system permissions in order to hide itself.
It uses several methods in order to avoid detection by antivirus companies:
- It prevents scanning tools from running, such as Windows Registry Editor, FileMonitor, etc.
- It terminates its own execution if it detects that a memory dump program is running, such as Procdump.
- It terminates its own execution if it detects that a debugging program is active.
Dialer.LIU 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.
- Via Internet, exploiting remote vulnerabilities: attacking random IP addresses, in which it tries to insert a copy of itself by exploiting one or more vulnerabilities.