According to a blogger at the SANS Internet Storm Center, hackers have been exploiting a vulnerability in Adobe Reader and Acrobat programs to install malicious code.
According to Arstechnica, hackers are able to use malicious banner ads as a host for an infected PDF. The PDF then installs the Zonebac Trojan, which sets to work deactivating antivirus products, modifying search results and changing banner ads.
Adobe’s 8.12 update supposedly fixes the problem, although it's claimed that Adobe has declined to explain what exactly the patch fixed.
The discovery and exploitation of this weakness raises some interesting questions about the security of the PDF standard, with some experts, such as Symantec’s Hon Lau starting to question how long it will be before people consider PDFs too vulnerable and avoid using them altogether.
Clearly Adobe has its work cut out in persuading us otherwise.