Shifting Spam Tactics -- Image-based Spam Makes a Comeback, PDF Spam
Continues to Wane, MP3 Spam Debuts but Remains Rare
In PDF spam
, spam content is embedded within attached .
During the quarter, Proofpoint also continued to update its machine-learning-based anti-spam technology to offer enhanced protection against the latest threats including PDF spam
(unsolicited email messages where the message "payload" is hidden inside of an Adobe Acrobat PDF file attached to the message) and other forms of attachment-based spam, such as Word document and MP3 audio spam.
Having first been identified in June 2007, August saw a dramatic rise in the amount of PDF spam
being relayed, only for it to trail away in similarly dramatic fashion shortly after.
The advanced methods used in Proofpoint's anti-spam solution offer extremely high effectiveness against all types of spam -- including "traditional" spam, image-based spam, PDF spam
and other forms of attachment-based spam -- averaging more than 99.
The report examines the appearance of new kinds of attachment spam such as PDF spam
and Excel spam together with the decline of image spam, as well as the growing threat of innocent appearing spam containing links to malicious web sites.
Spammers unveiled a new email tactic toward the end of the quarter: PDF spam