Spam is again on the rise, led by a flood of junk images that spammers have crafted over the past few months to trick e-mail filters. Called "image-based" spam, these junk images typically do not contain any text, making it harder for filters that look for known URLs or suspicious words to block them. Instead of a typed message, users will see only an embedded .gif or .jpeg image file urging them to buy pharmaceuticals or invest in penny stocks. Antispam vendor Cloudmark Inc. says that half of the incoming spam is now image-based on the "honeypot" systems it puts out on the Internet to lure spammers.

Read the full story here.