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61. Security updating key to thwarting annoying emerging modem hijacking

By Mark Alberstat

Although most computer users know about viruses, there is one type of attacker many users are not familiar with and that is a dialer virus, sometimes referred to as modem hijacking, dialer hijacking or Internet dumping.

These attackers are often worse than other types, as they often end up costing the victim hundreds of dollars in long-distance charges.

Dialers covertly use your modem to dial long-distance phone numbers, often to small African countries, and run up enormous charges on your phone bill.

Some of these programs operate while you're surfing the Net or reading your e-mail. Other versions operate when you're away from your machine, dialing numbers after your computer sits idle for long periods of time.

These programs can dial a number many times faster than a person can, sometimes about one call every second or two. The modem's owner is on the hook for these calls that are made to small nations that charge high fees for incoming international calls. Each call may cost several dollars in access fees, even if the call only lasts a few seconds. The four countries that are most often called by these programs are Sao Tome, Guyana, Guinea Bissau and Nauru.

Who can become a victim of these attacks? Any Internet user who dials into an Internet Service Provider for access. The vast majority of these dialers are downloaded into your machine when you, or someone using your computer, clicks to say yes on a popup box offering a great deal on some product.

Some dialers are, however, brought into your system when you use Internet Explorer through a type of plug-in called ActiveX. ActiveX programs run on a website and can be downloaded into your computer when you view a web page using them. If you keep your Internet browser up to date with security patches, your browser will ask you if you want to allow an ActiveX program to be installed. It is best to deny these requests, thus eliminating any chance of your computer being infected in this way.

To protect yourself against dialer virus attacks there are a few basic things you can do. The first is, of course, not to download anything from a website of which you are not completely sure of. It is also best to read all disclaimers and warnings before you download any software. Keep your anti-virus software up to date, install anti-spyware software and check your phone bill carefully each month. Some phone companies will make allowances for these charges but ultimately, they did occur on your line and you are, therefore, responsible for them.

One of the most popular pieces of protection software against modem highjacking is an Australian product called StopITNow! This software costs $21 but there is a free trial version available. Visit for all the needed information, including a link to the trial version.

The Mousepad runs every two weeks. It's a service of Chebucto Community Net, a community-owned Internet provider. If you have a question about computing, email If we use your question in a column, we'll send you a free mousepad.


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Originally published 5 June 2005


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