Spammers are always looking for techniques that can beat the spam filters. We have been seeing various techniques for spamming like obfuscating words, embedded text in images, spoofing urls, abusing social networking sites and many other techniques to avoid spam getting caught.
One of such technique that is used to fool the spam filters is ASCII art. It is an artful way of representing the image using text characters. The representation of image in characters was first done long ago to overcome the limitations of computers for displaying graphics.
Example:
______ _____ ______ _ _____ _____ ___ | ___ \ | ___| | ___ \ | | |_ _| / __ \ / _ \ | |_/ / | |__ | |_/ / | | | | | / \/ / /_\ \ | / | __| | __/ | | | | | | | _ | | |\ \ | |___ | | | |____ _| |_ | \__/\ | | | | \_| \_| \____/ \_| \_____/ \___/ \____/ \_| |_/
The clever thing is that each line has some random characters with _ and | characters which does not resembles any part of the word REPLICA. If we take the entire picture into consideration, the human eye can read it as a word. The spammers try to take advantage of this to pass through the spam filters and deliver the intended message as it is clearly readable by humans.
Not only are the words represented in this manner but even urls can be displayed in this way to avoid the blacklisting of the domains.
The ASCII art spam is not limited to only non-word characters. It can be numbers, alphabets and combinations of all, which can make things even worse for certain spam filters:
dP""b8 88 db 88 88 dP"Y8 dP 88 dPYb 88 88 `bo Yb 88 dP__Yb 88 88 `Y8b YboodP 88 dP""""Yb 88ood8 88 8bodP'
In the above email we can see that the spammer is advertising a pharmacy product without using the respective words yet is still successful in conveying the message.
We had seen this spam technique some time back but it had died away, recently however we have seen an increase in it again. McAfee customers are protected from this type of spamming technique.
