[转载]PDF spam —— a step ahead of image spam

信息来源：邪恶八进制信息安全团队（www.eviloctal.com）

Spammers take spam to a new level using the common PDF file format This white paper explains what makes spam such an unbearable problem and how spamming tactics are evolving daily to beat anti-spam software. The latest tactic is to use the common PDF file format to send image spam. By using PDF attachments to send images instead of embedding them in the body of the email message, spammers have taken the cat-and-mouse game with anti-spam software developers to a new level.