Security News > 2021 > May > Contract killer: Certified PDFs can be secretly tampered with during the signing process, boffins find

A pair of techniques to surreptitiously alter the content of certified PDFs have been detailed by researchers in Germany.

Using certified PDFs is increasingly common in business.

"All three can be used to stealthily modify a certified document and inject malicious content," their paper explained.

11 out of 28 annotations are classified as medium since an attacker can hide content within the certified document."

"If a certified document is opened in a common PDF application, signatures can only be added to free signature fields provided by the certifier. Adding empty signature fields is normally no longer possible within the application," the paper states.

"Only certified documents may execute high privileged JavaScript code in Adobe products," they said.

News URL

https://go.theregister.com/feed/www.theregister.com/2021/05/26/pdf_certificate_flaw/