Dialer.HAJ 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.HAJ 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.
It affects productivity, preventing tasks from being carried out:
- In the affected computer:
it displays pop-up windows; causes system slowdowns; it converts the computer into a platform for taking malicious action surreptitiously: spam sending, launch of Denial of Service attacks, malware distribution, etc.
It reduces the security level of the computer:
it changes the security settings of Internet Explorer, decreasing its security level; it opens one or more ports to allow remote access to the computer and takes action that compromises user confidentiality.
Dialer.HAJ 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 injects itself in running processes.
- It modifies system permissions in order to hide itself.
Dialer.HAJ 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.