If there is one thing for sure it is that spammers are creative in finding new ways to bypass anti spam filters. They send distorted pictures, add random text to their messages, zip or password protect spam, use excel files, pdf files and nowadays fdf files. Fdf files? What's that again?
Adobe Fdf is the file extension for the Forms Data Format which I'm sure most of you have never heard of before -- I have not.
The real beauty of the format for spammers is that the Adobe Reader is able to open and display the contents without problem. A great way for spammers to provide everyone with up to date news of stock market insider tips without having to rely on camouflage tactics to bypass spam filters.
The best way to handle this sort of spam is to create a new spam filter that would move mails with an .fdf attachment right into the junk folder. No company that I know of is sending .fdf files to their customers which means that it is 100% save to automatically move them to the junk folder.
Obviously, if you do receive fdf files by mail occasionally, you may want to whitelist the senders of those legitimate files to make sure they do not land in junk.
Update: Users who do not make use of Adobe Reader should be safe as well, as the majority of third party readers is not supporting Adobe's fdf file format. Viable alternatives are Nitro PDF Reader, Foxit Reader or the bare-bones reader Sumatra.
These alternatives are often a lot faster when it comes to opening pdf documents on the system, which is one of the reasons why many experienced users install them and not Adobe Reader.
The take away from this article is the following: Spammers may use lesser know file formats to send their spam messages to users. The majority of Internet users know that they should not open .exe files that are send to them.
Advertising revenue is falling fast across the Internet, and independently-run sites like Ghacks are hit hardest by it. The advertising model in its current form is coming to an end, and we have to find other ways to continue operating this site.
We are committed to keeping our content free and independent, which means no paywalls, no sponsored posts, no annoying ad formats or subscription fees.
If you like our content, and would like to help, please consider making a contribution:
Ghacks is a technology news blog that was founded in 2005 by Martin Brinkmann. It has since then become one of the most popular tech news sites on the Internet with five authors and regular contributions from freelance writers.