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Questions tagged [pdf]

Portable Document Format (PDF) is an open standard for electronic document exchange maintained by the International Organization for Standardization (ISO). Questions can be about PDF specific malware or protections.

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36 views

Do MS Word and Adobe Elf/Acrobat block javascripts from running?

I opened a pdf yesterday and found out it contained javascripts (that could possibly be malcious.) I wanted to know if the javascripts would trigger if I opened it in Word "protected view" ...
5 votes
1 answer
2k views

Can the conversion of a malicious PDF to image be exploitable?

Let's say I want to allow the customers of my website to upload PDF documents. What would be more safe to: Convert the PDF to image using a library and store it in my file server as an image? Can the ...
1 vote
2 answers
303 views

When receiving PDFs from unknown sources, is it sufficient to remove dynamic content to minimise attack surface?

My company allows customers to upload PDFs, JPEGs and PNGs to our servers, which are then viewed by clients. We want to minimise the potential for attack on the clients. While the image formats are ...
0 votes
1 answer
564 views

Risks of allowing users to upload PDF and XML files to be stored/retrieved from a DB (ASPNET MVC 5)

I'm modifying an ASPNET MVC 5 web site and a requirement is to allow users to upload an XML and PDF file. The XML file will be used to layout text on the PDF based on variables coming from within the ...
0 votes
0 answers
94 views

Malware in a PDF

I opened a PDF yesterday. How large would a PDF be that has malware? The one I downloaded was approximately 5 MB. If I opened the PDF on a browser, would the browser be infected? For some context: I ...
0 votes
1 answer
3k views

Volatility: AutoMagic Symbol Table error

I am trying to analyze the .vmem file from HoneyNet challenge 3: Banking Troubles (HoneyNet) using volatility3. But I can't seem to get past this error: PS C:\Users\<user>\Desktop\HoneyNet\...
1 vote
1 answer
118 views

Does PDF level compression implicitly cleans file of malware?

Recently I've been looking into PDF files security, specifically about malware exploiting vulnerabilities in PDF readers. I thought about one thing - does compressing PDF file (for example, by using ...
0 votes
1 answer
186 views

Fuzzy hash of a file

Could someone please explain this to me: When you use a fuzzy hash algorithm (ssdeep, tlsh, sdhash... or any other) to calculate the hash value of a file, does it calculate the hash based on the whole ...
2 votes
1 answer
546 views

Website with embedded PDFs and JavaScript for Acrobat

Context On my website, users can upload their PDF files, and then some, other users can view the uploaded PDF files. I was wondering if this could come with security issues. The uploaded PDF are ...
1 vote
1 answer
197 views

Secure PDF Document Transmission for US State Government Official

I have been requested to send a copy of a past year tax return to a US state office. I have been in contact with a tax official by email to send this copy through various means. This state is a few ...
4 votes
3 answers
976 views

How to harden Adobe Acrobat and Acrobat Reader [closed]

I found this recommendation by the CISA to disable Javascript in Acrobat Reader. Also, this article recommends to disable Flash and Multimedia, and the opening of non-PDF attachments. Both ...
1 vote
1 answer
320 views

How safe it is to view PDF file in browser without downloading the file into PC?

When I view the PDF file in a browser such as FireFox without downloading the file into my PC, does FireFox temporarily store the PDF file in my PC? I heard that FireFox has been sandbox heavily and ...
0 votes
0 answers
134 views

I am trying to identify suspicious content within a PDF file

I have a PDF file that has been sent to me as part of a suspicious email. I viewed the email as message source from within outlook. This gave me all raw text within the email. I copied this to ...
1 vote
1 answer
108 views

Do frequently crashing programs pose a bigger security threat than stable programs?

If I have an app that's frequently and randomly crashing, will it impose a bigger security threat (e.g: possible attack vector) than apps that are stable? Or are both apps equally protected from such ...
0 votes
1 answer
356 views

Is there a safe alternative to PDF?

As PDF may contain malicious code, is there any easy to use file format providing the same features ? If not, could you share recommendations to limit the attack surface for average users ? (exclude ...
0 votes
0 answers
40 views

How to "clean" PDF to remove non-text and non-images in Product User Manual? [duplicate]

I need guidance on, with the least security risk, how to edit Product User Manuals and Engineering Drawings PDFs from the internet. Antivirus is insufficient, according to advice from a website which ...
1 vote
2 answers
1k views

Check if javascript in pdf is malicious

I used Didier Stevens's pdfid.py to check a pdf, and it found js and automatic actions associated with the pdf: How do I check if this is malicious code?
0 votes
1 answer
220 views

Is it possible to use hashcat or john the ripper on a .drmz file?

I have n .drmz files which I can read with Javelin PDF Reader. Obviously to access the content I need a password, which I have, the same for each file. In case I don't have the password is there a way ...
1 vote
1 answer
181 views

Personally identifiable information in a PDF bank statement?

I have got to upload a sample bank statement PDF online which is going to accessible to everyone. I have obviously edited out all account details, names, codes, transaction particulars and the ...
0 votes
1 answer
504 views

Safest way to open PDFs on Android and iOS?

I was checking out Qubes' way of creating safe PDFs, but unless you use Qubes as a daily driver (and use DispVMs to open PDFs) it's still not viable to just use it to create image-based PDFs if you ...
62 votes
11 answers
109k views

How to safely view a malicious PDF?

I have a PDF with important information that may contain malware. What would be the best way to view it?
0 votes
0 answers
2k views

How to inspect for potential malware on pdf attachment?

I received an email at work the other day from a client (with the correct email address) that had a pdf attached. When I opened the pdf, it said the client had required the recipient to login to ...
5 votes
1 answer
3k views

What is the difference between PKCS#7 and CADES, PADES and XADES?

I am newbie in PKI. For signing a pdf documents we are free to consider each pkcs#7 format or PADES format. If I have some misunderstandings, please turn it on for me.
0 votes
0 answers
1k views

Android 10 downloaded suspicious files without my permission

This is my first question on this forum so please let me know if I need to clarify anything. My Android 10 Pixel 2 just downloaded 2 files without my permission today, both named something to the ...
0 votes
2 answers
1k views

Foxit Reader - disable JavaScript / Safely read PDF

Today I disabled JavaScript in my Foxit Reader settings because I hope to gain better security against malware embedded in PDF books I read. As some sort of simple check I tried to open a PDF with ...
1 vote
1 answer
201 views

Can websites, through cookies or other usual means, access PDFs opened in browser?

Can websites through the use of cookies or other usual means, see the content in a PDF (saved and opened locally or opened from the web) that is also opened in the browser at the same time, or in the ...
1 vote
1 answer
4k views

Are there any known vulnerabilities that exploit google's PDF viewer?

I have told my users for years not to ever click on PDF Documents if they are not 100% sure they know where it came from as they can sometimes be the delivery vector for malicious code. Recently, one ...
1 vote
1 answer
731 views

Can a PDF file make network requests to remote computers?

Do PDF files have the ability to ping a remote server such that the remote server will know that I opened the PDF file? If so, how do I stop that? I am using the Evince PDF reader on my computer that ...
1 vote
1 answer
401 views

Why do you need to wrap bash command inside another when opening a reverse shell?

In the CSAW 2022 web challenge, called "my little website", a youtuber in this video used a vulnerability in md-to-pdf to run arbitrary js, and this is the payload used: ---js ((require[&...
2 votes
1 answer
2k views

What is the format of PDF hash?

When I use a tool like pdf2john.py from John The Ripper on an encrypted PDF, it gives me an output like: testing1.pdf:$pdf$2*3*128*-1028*1*16*3ba51ab2b4f9210274ccb07b8da9ec59*32*...
1 vote
2 answers
239 views

HSM High Volume Keys

Our project is to apply digital signature to PDF, so each user should have their own key pairs and a certificate. To keep key securely, we plan to purchase HSM, but from what I understand HSM have a ...
7 votes
1 answer
8k views

Why won't pdf2john extract the password hash of this encrypted pdf? Getting blank results

New to the community, and to JtR and Hashcat as a whole, but after searching for a few days I couldn't find a solution to this specific problem. I have a password protected PDF file that I'm trying ...
0 votes
1 answer
177 views

Using PDF files from dubious sources

In one of my university courses, the lecture materials (solutions to homework assignments) are not fully supplied by the university itself, but have to be created by the students themselves: The ...
1 vote
2 answers
2k views

John The Ripper unable to crack long PDF passwords

Steps I follow: I protected a PDF with a long password (I am trying with 38 characters password). I created a dictionary that contains the password to crack the PDF with John the Ripper. I run john --...
9 votes
4 answers
19k views

How to detect malicious JavaScript in a PDF file?

Is having any JavaScript in a PDF file by definition dangerous or is it only dangerous when specific functions (for example eval) are used inside a PDF, in which case, what JavaScript functions are ...
0 votes
2 answers
4k views

Is it still possible to embed executables in PDF in 2022?

I have searched and found those posts how to embed exe file to pdf? and https://stackoverflow.com/questions/2941700/can-i-embed-an-exe-payload-in-a-pdf-doc-ppt-or-any-other-file-format, but they are ...
8 votes
1 answer
797 views

Security of PDF reader software

Are there any studies regarding the security of PDF viewer software from different vendors? I try to find the most secure reader.
20 votes
1 answer
55k views

How can I extract the hash inside an encrypted PDF file?

As long as I know, the encrypted PDF files don't store the decryption password within them, but a hash asociated to this password. When auditing security, a good attemp to break PDF files passwords ...
12 votes
1 answer
9k views

What are the security risks associated with PDF files?

What are the security risks associated with PDF files? There is, of course, the general risk associated with any type of file: that whatever application is used to read it will have a bug that can be ...
1 vote
3 answers
17k views

Is there a way to scan a pdf to ensure it doesn't contain anything that could be a virus?

The answers to Can a PDF file contain a virus? show that clearly it can! Sometimes we can be quite sure a certain pdf should not need to do anything sophisticated - for example a book in pdf form - so ...
0 votes
1 answer
2k views

What hidden metadata might be embedded in a PDF that is not visible "to the naked eye"?

I have edited a PDF file in Acrobat, which left some metadata and I am wondering: What metadata might be possible to discern from the end file if I were to send it to external parties? What actions ...
3 votes
1 answer
729 views

What encryption method is used on macOS Preview.app?

In order to send a file securely, I am going to encrypt/password protect a PDF file with Preview on macOS. Other question(s), such as this one have asked the method of encryption for PDF's in ...
0 votes
1 answer
552 views

Do pdf files pose a higher security risk than regular image files (png, jpeg, etc.)?

Do pdf files pose a higher security risk than regular image files (png, jpeg, etc.)? In my understanding is that most image files don't carry any security risk because all exploits were fixed, but ...
1 vote
0 answers
579 views

A PDF ran GetAdaptersAddresses. Should I be concerned?

I received and opened a PDF that ran: GetTickCount IsDebuggerPresent SetWindowsHookExW Sleep GetAdaptersAddresses These are the 2 files it wrote: C:\Windows\ServiceProfiles\LocalService\AppData\...
1 vote
1 answer
3k views

Strange virustotal tags on pdf file

I've received PDF at work, which I then ran through virustotal scan out of habit. It turned out to be clean, but at the same time some tags caught my attention, namely: checks-user-input detect-debug-...
1 vote
2 answers
530 views

Vulnerabilities in Receiving User-Submitted PDF Files Through HTTP(S)

For context; I have a web application that allows users to upload a PDF file from which the web app extracts certain information by parsing it. The app then sends this information to another server ...
6 votes
2 answers
8k views

Extract malicious code from PDF file

I've a PDF file that contains some malicious code; when opened the processor usage maxes out and the fans run at full rpm. The pdfid.py produces the following output: PDF Header: %PDF-1.7 obj ...
16 votes
2 answers
6k views

Is cloudflare injecting tracking code for PDF requests in browsers via the browser PDF plugin?

Opening a PDF link in the browser (e.g. google chrome with the ootb PDF viewer plugin) apparently indicates that when the PDF is hosted on a cloudflare-facing domain there is additional data present ...
4 votes
3 answers
12k views

Gmail warns about encrypted PDF file

I recently received a PDF file that, when attached to a gmail message, causes a warning to be displayed as follows: Encrypted attachment warning – Be careful with this attachment. This message ...
0 votes
0 answers
908 views

Get encrypted PDF password

For a CTF challenge, I got a locked PDF file with a data folder that contains images, a plaintext file and a wav audio file. I used pdf2john.pl to get the password hash and I performed a brute force ...