For the London Free Press – September 17, 2007
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Tired of receiving e-mails offering to help you lose weight, get rich and earn a diploma by simply clicking on a handy link?
You’re not alone.
A recent survey by Symantec found that spam levels remain high, accounting for about 66 per cent of e-mails. Despite efforts to combat junk e-mail, spammers continue to adopt new methods to evade detection by e-mail filters.
One difficulty faced by those working to reduce spam is the speed with which spammers change their tactics.
As recently as six months ago, almost 52 per cent of all spam received was image spam, in which the text of the message is presented as a picture in an image file.
Last month, this form of spam accounted for only eight per cent of all spam.
This is an indication that anti-spam filters are increasingly successful at combating this type of spam.
To fill the gap left by this decline, newer styles of spam are on the rise. In the last month the percentage of spam messages utilizing PDF images rose from three to seven per cent.
While PDF image spam is still nowhere near as popular as image spam was, it’s on the rise.
Two other new styles of spam are emerging. These involve the attachment of Excel and zip files to spam messages.
In the past, spammers pushing stock and pharmaceutical spam were significant users of image spam.
This variety of spam has witnessed a noticeable increase in usage by spammers looking for a replacement outlet.
While generally reliant on staying one step ahead of those combating spam, spammers still depend on some “traditional” methods.
Fake greeting cards remain a spammer favourite. These cards may appear to come from legitimate sources and instruct the user to click on a link to access their “greeting card.”
When the link is clicked a downloader accesses the Internet and downloads a Trojan Horse, a program that installs harmful software onto the computer.
E-mail users should be wary when clicking on such links in e-mails and watch for warning signs.
Examine the link and watch for anything suspicious, such as an exposed IP address which indicates the e-mail is not from a legitimate e-card company.
Changing the type of spam message isn’t the only tactic used by spammers.
The last month witnessed an increase in the percentage of spam messages from URLs using China’s top level domain (TLD), “cn.”
At the same time, the number of messages from URLs using “hk” (Hong Kong) TLDs dropped significantly.
This shift may be due to the enactment of new anti-spam laws in Hong Kong on June 1.
There are other possible explanations for the increase in use of China’s TLD.
In the past, spammers have used various TLDs to register names that reflect the product or service they offer.
Over time, the names become blacklisted, forcing the spammers to find new TLDs.
Switching to new TLDs can also be a way to avoid spam filters.
Unfortunately spam is not likely to go away any time soon. The battle for supremacy between spammers and spam filters will continue.