A dialer is a computer program which can use a modem to create a connection to a private network or the internet. A dialer program will utilize a modem through a telephone line to connect and normally use Point to Point Protocol (PPP). The dialer may be part of your operating system or it may be provided by an internet service provider.

There are many fraudulent dialer programs today which are used to scam victims out of hundreds or thousands of dollars. Malicious dialer programs may connect a user's computer through their modem to an expensive long distance number or 900 number. The dialer is usually installed because an attacker used or exploited a security hole or vulnerability in the victim's computer. The dialer program can also be installed with a free game or other free computer program. The dialer may then change the victim's default internet connection dialing number to an expensive 900 number or some other high cost toll number. The victim may be totally unaware of the dialer's presence on their computer until they get their telephone bill.

Dialers may act different ways. Some dialers will use the modem when the computer is idal and dial a 900 number or international number when no one is using the computer. Some dialers may get loaded when the victim visits a hostile site which may be a site with adult content. The dialer may be loaded on the victim's computer without their knowledge. Then the dialer will drop the victim's internet connection and re-establish it using an international or 900 number which will charge the victim by the minute. A pop up window may ask the victim to change internet service providers. Much information may be in fine print and mixed with other information about free content or material. This process is known as internet dumping.

Terms for what malicious dialers do are "dialer hijacking" and "modem hijacking". Anyone who has a computer with a modem connected to a telephone line can be affected by dialers. Many anti-virus programs can remove dialers. Also Ad Aware and Spybot Search and Destroy can remove dialers. If a dialer infects a computer, security experts recommend that the computer be completely re-installed to be sure the dialer or other programs it installed are completely removed.

Malicious dialers are another good reason for home computer users to practice good home computer security. Some of these home security practices include:

  1. Using an updated real time anti-virus protection program on your computer at all times.
  2. Using a personal firewall to protect against worms
  3. Keeping your computer operating system updated on a regular basis.
  4. Setting your internet browser settings to be more secure and not allow websites to install software without the user's consent or knowledge.
  5. Educating yourself about computer security and many of the fraudulant practices being used on the internet today.

There are other security measures which should be taken. The following tutorials provide more information: