PDF malware adopts another obfuscation trick in attempt to avoid detection

[SysAdMini]

http://nakedsecurity.sophos.com/2012/04/05/ccittfax-pdf-malware/

Filters are used by PDFs to compress or store data to either make the file smaller (Flate, CCITTFax) or allow it to be read as text (ASCIIHex).

By combining the filters in weird ways the malware author hopes to bypass detection by malware scanners and deliver a malicious payload to the victim.

example
http://wepawet.cs.ucsb.edu/view.php?hash=e44cc8b05cbca3500848285095704f8b&type=js