Security vendors report a marked increase in image-based spam, including a couple of new exploits. Image spam, in which an attacker camouflages a message in a picture or some other graphical form, has shown incredible growth in the past few months. Vendors generally agree image spam made up less than 15 percent of spam traffic during the first half of this year. Attackers have responded with a variety of exploits designed to circumvent these graphics filters. The simplest of these use unusual fonts or image formats, such as PNG, often are not spotted by currently available image-scanning anti-spam tools.”]
Source: https://www.darkreading.com/analytics/spam-victims-get-the-picture