Virus scanners recognize the code of most viruses. Therefore, hackers split the code and distribute it often through encrypted- as smaller units of code in PDF documents. PDF docs consist of objects like text, fonts, spaces, forms,and hyperlink. there are at least 10000 objects in every 100 pages. Hackers split and distribute malicious codes to several objects so that they cannot be detected by virus scanners.
57% of web based malware attacks target vulnerabilities in PDF readers.
Ways to protect your PC from infected PDF files.
The first line of defense is to keep anti-virus software and Adobe Reader up to date to automatically scan and repair infected PDF files.
1. Switch Off Scripts:
In Adobe reader deactivate scripts in ‘Edit|Preferences|JavaSript’. In the menu item ‘Authorizations’, prevent the execution of external programs.
2. Use alternative PDF reader:
Since most of PDF exploits target Adobe Reader, an alternative like Foxit Reader is naturally more secure. Of course, this should also be updates regularly.
3. Online File Check:
Criminals send infected PDFs via email. To check such files, upload them with VirusTotal Uploader or use any other scanner.