Google tightens Gmail spam filtering

Google is boosting Gmail’s ability to detect and block malicious emails from spammers and scammers that exploit similarities among Unicode characters to dupe users into clicking on bad links.

Unicode provides a standard for character encoding for all the writing systems in the world, along with technical symbols, punctuation and other text characters.

Because characters among different scripts are often very similar—such as the Latin and Cyrillic scripts’ characters for the lowercase letter “a”—spam and phishing emails often combine them in website links that otherwise look legitimate to the unsuspecting eye.

Scammers set up a site with the URL of a known business—a large bank or retailer—using a mixture of Unicode characters, making the URL look like the one from that business. Then they include a link to that malicious site in spam and phishing emails, hoping people will click on it.

“The Unicode community has identified suspicious combinations of letters that could be misleading, and Gmail will now begin rejecting email with such combinations,” wrote Google official Mark Risher, from the company’s Spam & Abuse Team.

Google will use the Unicode Consortium’s “Highly Restricted” open standard designation because the company believes it strikes a good balance “between legitimate uses of these new domains and those likely to be abused,” Risher wrote.

The Unicode encoding standard provides the basis for “processing, storage and interchange of text data in any language in all modern software and information technology protocols,” according to the Unicode Consortium.

Unicode is aimed at developers who want their software applications to work in any language in the world.