Why is PDF File Protection Often Weak? Seeking Community Insights

[Saher Naji]

Hello Esteemed Adobe Support Community Members,

Let's embark on a collective journey to uncover the underlying causes behind the vulnerability of PDF file protection and to brainstorm potential remedies for bolstering PDF file security.

To illustrate, consider this succinct comparison: When we protect a Microsoft Word document from editing (not opening), it becomes notably challenging for unauthorized access using free online tools. However, the scenario changes when we seek to safeguard PDF files against editing. It appears alarmingly simple for various free tools, like smallpdf.com, to swiftly unlock them in mere seconds, regardless of the complexity of the password employed. For instance, I recently used the following password: S$7jK#4hM&8fQ9pN5zW@3xY2tV6dL1sU0oI, and smallpdf effortlessly bypassed the protection.

To clarify my specific requirement, I am seeking a solution to protect my fillable forms. I want to ensure that no one can access the underlying JavaScript codes, modify the document's text or layout, or manipulate its page content by adding or deleting pages. My objective is to allow users only to fill out the forms without any ability to alter the document's integrity.

Is such a level of protection attainable?

Furthermore, I would like to mention that I am open to incorporating JavaScript code into my PDF document to enhance its resistance against unlocking by free online tools.

Your expertise and guidance in this matter would be greatly appreciated.

Thank you for your valuable insights and assistance.

Respectfully,

Saher

[try67]

This is a complicated and technical matter. The bottom-line is there's no 100% secure protection. You can only make the life of those willing to hack your file more difficult. One way to do that is to apply a File-Open password, not just a File-Edit one. That will encrypt the file's entire contents and make it more difficult (but not impossible) to read them without the latter.

If you want to hide your code you can obfuscate it (there are plenty of free tools online that will do it for you). Again, not a 100% secure solution, but it can definitely make it difficult for someone to read it.

And if you want to prevent someone from editing the file (or at least, make it possible to prove the file was edited), you should digitally sign it before sending it to them (but after applying the security policies to it!).

[Saher Naji]

Thank you @try67 for sharing your insights and suggestions. I understand that achieving 100% security can be challenging, but I appreciate your guidance on making it more difficult for unauthorized access.

The idea of digitally signing the file for editing prevention is valuable.

[ls_rbls]

Hi @Saher Naji ,

As  @try67  mentioned, there is no 100% protection, but this is not only true of Adobe Acrobat. It happens with Microsoft products, cloud-based services, GoogleDocs and more.

What is important to keep in mind is which type of measures should be implemented to mitigate weak protection.

In which case, and most likely, you'll need a paid-for third-party solution in order to be able to mitigate as many weaknesses as possible.

One example is how to implement app containers, User Access control services (managed at the networking operating system level), file sharing trust policies, file encryption/decryption mechanisms, and digital rights management (to name a few important considerations), in addition to preventing file copying, file editing, file printing and file Save As.

[Saher Naji]

Hello @ls_rbls 

Thank you for your insights and highlighting the importance of implementing robust security measures. I appreciate your perspective on the challenges of securing documents across various platforms.

You've raised valuable points, and I will certainly explore paid third-party solutions to enhance the security of my PDF fillable forms, Could you provide more details here please?. Your mention of app containers, User Access control services, and digital rights management is particularly helpful.

I'm committed to taking steps to mitigate weaknesses and improve the overall security of my documents. Your input is much appreciated.

Thanks again for your contribution to this discussion.

[MikelKlink]

Please consider, if someone can open a given file for viewing or filling in forms, they have in principle access to all the information in the file to create manipulated copies, e.g. copies without encryption. 

How easy or how difficult it is to do so depends on details. In the case at hand, PDF files, the file format (including the encryption details) is subject to an open specification. Thus, it is obviously is easy to do so.

The situation should be similar for Word files because their format meanwhile also is an open standard. Maybe there aren't as many web tools all over the place to remove encryption as for PDFs, but that only shows that there is a larger interest in those tools for PDF than for Word, not that there is conceptually a difference. 

(I just googled for "unprotecting ms word" and got quite a selection of tools which promise they can "unprotect a Word document for editing with 100% success rate. And it can be done within seconds" in these or other words. Thus, I cannot see the notable challenge you mention...)

You can try and use third-party, proprietary encryption which requires custom Acrobat plugins to work as proposed by @ls_rbls . But that would mean that the users of your PDFs also have to install that plugin (restricting them to Acrobat). Also this merely means that fewer people can unprotect the file.

In my opinion the better option would be using digital signatures as proposed by @try67 and only accepting filled-in PDFs with that signature still integrated and valid.

[Saher Naji]

Hello @MikelKlink

Thank you for sharing your insights and highlighting the challenges of securing documents, especially in open file formats like PDFs and Word documents. I appreciate your detailed explanation of the accessibility of information within these files.

You've raised a valid point about the availability of web tools for removing encryption from various file formats, including Word. It's clear that there is a significant interest in these tools, which can indeed diminish the perceived security of document protection.
Admittedly, I did not notice or know about this vulnerability in MS-Word before.

I'll take into account your suggestion of using digital signatures. Ensuring that filled-in PDFs are only accepted with valid signatures seems like a promising approach to enhance security and maintain document integrity.

Your input is valuable, and I'm grateful for your contribution to this discussion.

[JR Boulay]

There are several levels of protection in PDF, from the most basic to the most secure.
The one you tried is the most basic, the most secure would be a nightmare for your users.
Between the two you should be able to find what suits you (certification, signature…).

See:

https://community.adobe.com/t5/acrobat-discussions/create-protect-amp-delete-digital-ids/td-p/115079...

[Saher Naji]

Thank you @JR Boulay for pointing out the various levels of protection in PDF documents, from basic to the most secure. I understand that the most secure options can be challenging for users. I'll certainly explore the middle ground to strike a balance between security and usability, including options such as certification and digital signatures.

I'll take a look at the resource you mentioned to gain a better understanding of these security options. Your guidance is appreciated.

[JR Boulay]

You can also read this old document, which explains the problem (even if the name of the popular cracker software has changed):

http://www-2.cs.cmu.edu/~dst/Adobe/Gallery/PDFsecurity.pdf

[Saher Naji]

Thanks @JR Boulay 

[Saher Naji]

Hello Everyone,

I want to express my sincere gratitude to each of you for taking the time to share your valuable insights and suggestions on the challenges of PDF file protection and document security. Your expertise and perspectives have been incredibly enlightening and helpful.

It's clear that achieving the perfect balance between security and usability can be a complex endeavor. As we've discussed, there are various methods and tools available, each with its own strengths and limitations.

I also share the hope that Adobe, as a leading great software provider, will continue to innovate and potentially introduce advanced tools that can simplify the process of securing PDF forms while maintaining ease of use. Such advancements would undoubtedly benefit users like us who rely on these tools for various purposes.

Thank you once again for your valuable contributions to this discussion.

Warm regards,
Saher