Comment "OMG WTF PDF" lecture (Score 1) 202
If you're wondering what they're talking about you should watch this video. http://www.youtube.com/watch?v=54XYqsf4JEY
For a demo, see the 38:00 mark. The windows "calc.exe" is modified to simultaneously a valid windows exe, a valid zip archive, and a valid PDF. The same file can appear benign to anti-virus tools even though there is malware contained in the file when interpreted in certain ways.
-molo