Ebook Worms: How to Spot and Avoid PDF Malware (2023)


  • How do PDF files contain viruses?
  • Are PDF books safe?
  • How can infected PDFs contaminate your computer?
  • Malicious script in PDF
  • Malware disguised as PDF (Phishing PDF)
  • Emails containing infected PDFs
  • Fake Clickbait Book
  • Is it safe to download free PDFs from online libraries and search engines?
  • Where can I download e-books without viruses?
  • How secure are other e-book formats?
  • What rules do you follow to avoid becoming a bookworm?

Portable Document Format (or PDF as we know it) is probably one of the most common file formats for sending documents. It's everywhere from schools to offices and banks, successfully replacing printouts -- which is why criminals love it.

Compared to rich text files like Microsoft Word's DOCX or Apple's PAGES files, PDF files are not easy to edit. Since you can't just open a PDF and edit it as you wish (even if you have special and often expensive software), PDFs can be used for contracts, bank statements, and any other important document that needs to be signed and sent.

The "fill and sign" functionality of PDFs is at risk. They work in PDF with the help of special scripts. Unfortunately, this means that malicious code could be lurking in or alongside such scripts. Viruses hidden in PDF files can quickly infect your computer, whether it's a computereven a Mac.

Once you download the book, it's hard to findscientific report, orFree PDF templatesFor your small business (especially if such files come fromunreliable site), you might find a nasty surprise inside. Even worse - your PDF may just be a virus masquerading as a PDF file.

(Video) HACKERLOI.pdf

Let's see what dangers lurk in PDF files and how to deal with them.

How do PDF files contain viruses?

PDFs can contain viruses that embed code that makes the document signable and (to some extent) editable. The mechanism is very similar to that of a Microsoft Word file infected with a virus. While their malware hides inside macro scripts, infected PDF files will contain malicious JavaScript code.

Are PDF books safe?

A PDF is not an executable file, so it can't infect your machine while it's resting on your hard drive—the malware in the PDF needs to be interpreted and run by PDF reader software.

This is why PDF viruses cannot infect most older e-readers and modern e-paper and e-ink books. Dedicated email readers run highly stripped-down versions of the Linux operating system or the underlying custom operating system, so they cannot interpret and run malicious scripts.

Unfortunately, Android-based e-readers with regular touchscreens, such as devices such as Amazon's Kindle Fire, can be vulnerable. iOS devices should be safe from viruses in PDF files due to the app's memory sandbox. However, manyiOS viruses appear all the time, so be careful.

PC and Mac devices are most vulnerable to threats hidden in e-books. This is because software that opens and edits PDF files on desktop and laptop computers can interpret and run malicious code injected by hackers.

How can infected PDFs contaminate your computer?

Let's see what the PDF file containsmalwareInfecting your computer and where such files usually come from.

(Video) Do I have a PDF virus ?

Malicious script in PDF

PDFs often contain scripts for extended functionality. For example—in addition to filling and signing features—they can display the current date, add a print button, format data, perform calculations on input, and more. Such scripts can be added using JavaScript using software such as Adobe Acrobat Pro. Unfortunately, hackers can use more technically sophisticated methods to add malicious code to PDF files.

PDF files require PDF reader software to open and view their content. In doing so, the PDF reader becomes an unwilling accomplice to the hacker, as the application itself or its plugins will be able to run the embedded code. Third-party plugins in PDF reader software can also be an entry point for malicious scripts - you should disable them if possible.

Ebook Worms: How to Spot and Avoid PDF Malware (1)

Malware disguised as PDF (Phishing PDF)

you may have heardphishing by e-mail— Hackers send you emails pretending to be someone else and try to get you to click on links that can steal your information or infect your computer with viruses. There are two variants of PDF phishing:

Emails containing infected PDFs

A method very similar to ordinary identity theft. The usual execution of such an emailBetter than your average phishing emailand target specific recipients. There will be no suspicious links in the email content. However, it will contain a PDF file with a script virus, a download link to a malware file, or a Trojan virus disguised as a PDF in an attachment (similar to document.pdf.exe).

Fake Clickbait Book

These PDF files masquerade as books you want to download from the Internet. When you search for a particular book or document on the Internet, you may come across a free download link.

At first, it might seem like you've struck gold — the author, title, and cover match what you're looking for. Then there's the actual introduction, and maybe even a few pages hacked from the official online review.

A few pages down, however, the text ends, and there is a download link that supposedly takes you to a full copy of the book. At best - the link will take you to a premium site with pirated content. In the worst case - the link will get a virus. So take no risk and avoid clicking on such links.

(Video) How can a PDF file contain a virus scan failed

Is it safe to download free PDFs from online libraries and search engines?

The first question you should ask about online libraries - is it illegal to download free PDF books? It is not illegal to download books that are free or have entered the public domain due to copyright expiration. However, most of the books on sites like PDFdrive are pirated content. Their disclaimer usually warns against downloading books you don't have permission to download for free.

PDF driveris one of the largest collections of free PDF files to download. So is PDFdrive safe? It includes everything from legitimate free books, educational materials and voluntarily shared files to pirated content - the danger is that anyone can add an eBook file to anythingmalwareLurking inside at some point.

Although sites like PDFdrive, Library Genesis, or the Internet Archive try to keep their sites and content secure, much of the content is stolen, not checked for copyright infringement, and could be hijacked and added to by anyone, including cybercriminals. criminals.

Trojans, fake PDF files, and malicious scripts can sneak into any PDF you try to download. The IPirate website strives to provide its readers with quality content to keep them coming back or clicking on ads. However, it is impossible to keep track of billions of books, documents, magazines, etc.

Ebook Worms: How to Spot and Avoid PDF Malware (2)

Apps that offer free e-book downloads carry the same dangers as free online libraries. They are often nothing more than application-based wrappers or shortcuts to some external network library. Worse, such installable apps can become malware entry points for your iPhone, iPad, or Android phone.

Ebook Worms: How to Spot and Avoid PDF Malware (3)

It seems that free online libraries are not only a source of tempting freeware, but also good repositories for malware. Fortunately, there are places where books can be downloaded legally, sometimes for free.

Where can I download e-books without viruses?

The safest places to buy and download e-books are from reputable booksellers such asAmazon,Barnes & Noble, book chapteriTunesorgoogle player, the official online bookstore, or download directly from the living authors. also havebooks in the public domainFree so you can read something interesting without having to spend money right away.

(Video) Clean ANY malware or virus off ANY Windows computer with one FREE and SIMPLE program!

Ultimately, the safest way to purchase and read e-books is through an official reseller. Especially if your target device is a dedicated e-paper or e-ink reader and not a smart tablet in full disguise (Kindle Fire, we're looking at you). This way you also don't have to worry about the format of the book you're downloading.

How secure are other e-book formats?

Can e-book formats other than PDF contain viruses? Well, it's a lot harder, but it's still possible to sneak a virus into your Kindle's MOBI or AZW files. Infected EPUB, the preferred e-book format for iPhone and iPad, could also be real, as EPUB files are essentially special archives containing HTML, CSS, and JavaScript scripts.

But as mentioned earlier, malicious code needs an interpreter. Therefore, e-ink/e-paper digital e-readers are likely to be safe even if they carry infected e-books. However, there may be consequences if such files are opened on your computer.

What rules do you follow to avoid becoming a bookworm?

As you know, even seemingly harmless PDF or EPUB files can infect your computer. So, if you really need a book but can't get it through a trusted online vendor, before you download it from some dubious website, try:

  • Look in the library. You'd be surprised what you can find in your local library or your college or university library.
  • Check to see if it can be purchased directly from the author or current copyright holder.
  • Look for different formats - the book is available as an audiobook or video lecture.

If all else fails and you need to get a book from a free online library, there are several ways to protect your device.

How to avoid getting viruses from PDFs (or other e-book formats):

  1. Using pre-verified online libraries that require registration (e.g.graffiti).
  2. Make sure there are no mistakes in the title or the author's name. If so, you may have spotted a fake.
  3. Do not open e-books directly on your computer - use a cloud reader (e.g.pocket cloudor the Google Drive preview feature) instead of opening suspicious files on your computer.
  4. If you must open this book on your computer, please disable third-party plug-ins and JavaScript execution in your e-reader settings.
  5. Before opening the PDF file, scan it for viruses with antivirus software.
  6. Do not click on any links in books or documents.

If you suspect that a PDF file has infected your computer, run a full antimalware scan using your antivirus software.

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Use these precautions and never download suspicious PDF files from untrusted sites if you can avoid it. If the machine is infected, it is better to spend money on repairing the machine than to buy the book. Happy reading!

Read more:

  • How to remove viruses and other malware from your computer
  • 4 computer virus symptoms you need to know
  • How to browse privately on any browser and any device


How can I make sure a PDF is virus free? ›

Scanning a PDF for viruses on a PC.
  1. Right-click the file or folder.
  2. Select Scan with Microsoft Defender.
  3. Follow the instructions that appear for Scan options.

How do you tell if a PDF is a virus? ›

How to Check PDF Virus? If you ever receive any PDF from any untrusted sources, it is recommended to scan the file before opening it. Email providers like Gmail have inbuilt malware scanner for file attachments. They implement the technology of VirusTotal so you can be assured.

Can you get a virus from previewing a PDF? ›

Are PDF books safe? A PDF is not an executable file, so it cannot infect your machine while sitting idle on your hard drive — the malware in a PDF needs to be interpreted and executed through PDF reader software. This is why a PDF virus cannot infect most older e-readers and modern e-paper and e-ink books.

Can you get malware from a PDF? ›

More than that, PDFs can have JavaScript, and it is known to be one of the main channels for distributing malicious code. If a PDF file can execute system commands or contains multimedia, it is where a virus can hide. Finally, if you use a third-party app for opening a PDF file, you may be exposed to risks.

How do I know if a PDF is secure? ›

To view the security settings of a document, choose File > Properties in Acrobat or Reader. From the Document Properties dialog box, click the Security tab. If you have trouble opening a PDF, or you're restricted from using certain features, contact the author of the PDF.

How do I know if a PDF has macros? ›

If there is a letter “m” next to the stream number, this indicates that there is a macro included in the stream.

Does printing PDF remove virus? ›

No. "Printing to PDF" essentially captures an image of the website and none of the code contained within it. That said, before visiting a website like that you should likely make sure that your browser isn't vulnerable to whatever malware it's distributing.

What happens if you open a PDF in a phishing email? ›

If you downloaded any attachments from a phishing email, don't open them — they could contain malware that can steal your personal information or lock you out of your data.

How can you tell if a PDF is real? ›

Using digital signatures is also an appropriate way of checking the validity of the Pdf File. To confirm the changes made in a file use digital signatures if the file is edited the digital signatures will be removed that would help you identify any changes made in the pdf file.

Can a PDF track you? ›

Can you track who opens a document? Yes, but you need a licensing system to identify the user, and the ability to lock a PDF to a device so you have certainty of who you are tracking.

Is opening PDF in Chrome safe? ›

Just like we do with web pages viewed in Chrome, we've built in an additional layer of security called the “sandbox” around the Chrome PDF viewer to help protect you from malware and security attacks that are targeted at PDF files.

Is it safe to download PDF books? ›

Always buy books and digital content from legitimate retailers. Unless it's from a trusted retailer, some ebooks may contain malicious software that can install malware, spyware, and viruses in your computer. Do not distribute ebooks unless the company or author allows it.

How do I scan a file for viruses? ›

  1. Click on Start.
  2. Click on Settings.
  3. Click on Update & Security.
  4. Click on Windows Security.
  5. Click on Virus & Threat Protection.
  6. Under Current Threats, select Quick Scan/Threat History.
  7. Hit Scan Now.
Jan 24, 2023

Can EPUB files contain viruses? ›

epub, . zip and .exe files contain malware that could give your computer a virus, install spyware to monitor your web-surfing habits or place adware on your system. Always make sure you have reputable antivirus software like Norton Security in your device to catch those nasty viruses.

Does Google Drive scan for viruses? ›

Google Drive screens files for viruses and malware to prevent downloading infected files and help protect your data and computers.

How do I secure a PDF safely? ›

Open a file in Acrobat and choose “Tools” > “Protect.” Select whether you want to restrict editing with a password or encrypt the file with a certificate or password. Set password or security method as desired. Click “OK” and then click “Save.”

How do I know if a PDF is corrupted? ›

Open the PDF file: The first step is to try opening the PDF file in a PDF viewer or editor. If the file opens without any issues, it is likely not corrupted. However, if the file does not open or displays an error message, it may be corrupted.

How do I protect a PDF with security? ›

Add a password to Adobe Acrobat (pdf)

Open the PDF and choose Tools > Protect > Encrypt > Encrypt with Password. If you receive a prompt, click Yes to change the security. Select Require a Password to Open the Document, then type the password in the corresponding field.

How do I know if text is embedded in a PDF? ›

Once you have opened the correct PDF in Acrobat, go to File > Document Properties. 3. Select the tab at the top that says Fonts and then look for the fonts that have (Embedded Subset) at the end of their name. These are the fonts that are already embedded.

What are macros in pdfs? ›

The PDF macro displays the content of a PDF document on a page. First attach the document to a page, then use the macro to display the document.

How do you inspect a macro? ›

Open the workbook in which you stored the macro. Click VIEW tab on the Ribbon. Click Macros. Select View Macros from the dropdown list.

How do I sanitize a PDF? ›

Choose Tools > Redact. On the Edit menu, choose Redact Text & Images. Select the text or image in a PDF, right-click, and select Redact.

How do I remove security from a PDF to print? ›

Choose “Tools” > “Protect” > “Encrypt” > “Remove Security.” Remove Security: The options vary depending on the type of password security attached to the document. If the document has a Document Open password, click “OK” to remove it from the document.

Can printers carry viruses? ›

Due to the majority of today's multi-functional printer's having wireless capabilities, it opens them up as an attack gateway and makes them susceptible to viruses and malware. In this post, we share the best security software you can employ to protect your printer, and ultimately your business.

Do spammers know if you open their email? ›

Can Scammers See That I Opened Their Email? It depends. Scammers will be able to tell that you opened an email if you download any attachments or click on any links (which you should NEVER do), or if your email client automatically loads any images that are embedded in the message.

How do I secure a PDF before emailing? ›

How to secure a PDF.
  1. Launch Adobe Acrobat and select the Protect tool from the Tools menu.
  2. Choose your protection settings. ...
  3. Once you've protected your file, save it as a separate copy for safekeeping.
  4. Select Share With Others from the top toolbar.
  5. Add the recipients' email addresses. ...
  6. Select Send to share your file.

What happens if you open a suspicious PDF? ›

The PDF may be infected with malware that steals login credentials and other data. If not infected, any links inside the PDF may take you to an illegitimate phishing site. For more information on what to do if you receive a phishing email check out “What to Do if You Click on a Phishing Link?”

How do you tell if a PDF has been manipulated? ›

Under the 'Description' tab there will be the date and time the document is created and the date and time it was last modified. This information should be the same if the PDF has not been modified after creation. If the file is a scanned document which has been emailed to you, look for discrepancies in the fonts.

How do I verify a PDF digitally? ›

  1. In the signature Properties window click Show Signers Certificate button. Following screen will be displayed once you click on it.
  2. Once you click on OK button, following window will be displayed. ...
  3. Click Ok button in the following window. ...
  4. Once the certificate validation is done, you will get the following approval.

How do I stop PDF tracking? ›

How do I remove track changes from my PDF proof?
  1. Open the file in Microsoft Word.
  2. Ensure that the Reviewing toolbar is visible. Activate in Word by clicking View->Toolbars->Reviewing.
  3. From the Reviewing toolbar: Select Track Changes->Final Showing Markup to display all changes. ...
  4. Save the document, and then re-upload it.

How do I remove metadata from a PDF? ›

Go to the "File" tab and choose the "Properties" > "Description" option. You can then view the metadata of the PDF document. To edit or delete metadata on PDF, select the information that you want to delete. Using the "Backspace" or "Delete" key on the keyboard, you can easily remove the metadata information.

Can you tell if someone has opened a PDF? ›

Adobe Acrobat Sign is one portion of the Adobe software system. This software allows you to track electronic documents or PDFs that are sent through Acrobat Sign. With the system, you are able to get real-time notifications of when the documents are opened and signed.

Is it safe to open PDF on iPhone? ›

You're phone cannot get a virus. And opening a PDF on an iPhone is perfectly safe. If it has a link in it don't click on the link or answer any information that it asks for. That's really the only risk.

Is it safe to read PDF in browser? ›

The safe way to view a PDF is inside the Chrome or Firefox browser. Printing a PDF directly from Chrome (or Firefox) to your printer is reasonably safe. The unsafe way to view a PDF is with your favorite PDF-viewer app such as Adobe Reader.

Why has Chrome taken over my PDF? ›

Some logical possibilities include that: You don't have a PDF reader or software downloaded. Your default settings on your PDF software might be set to a web browser. You haven't turned off Chrome's automatic setting to work as a PDF viewer.

Should I open PDF from email? ›

When you know the sender, be skeptical because some viruses can leverage your contacts' trust in order to spread. For that reason, when you see an unknown sender's emails, make sure to not open any attachments with a PDF file extension.

What is the downside of PDF? ›

Since PDF files are usually in A4 format and portrait orientation, it can be difficult to read them on standard computer screens. The aspect ratio of a typical computer or laptop screen is 16:9. This means you usually need to zoom in to be able to read any text and you'll spend a lot of time scrolling through the PDF.

How do I check my iPhone for malware? ›

How to check your iPhone for malware
  1. Look for unfamiliar apps. If you're anything like the average smartphone user, you've probably downloaded dozens (if not hundreds) of apps. ...
  2. Check your data usage. ...
  3. Check power consumption. ...
  4. Keep an eye on pop-up ads. ...
  5. Scan your phone using antivirus software.
Nov 6, 2022

How can I detect malware without antivirus? ›

The first step towards removing a virus is identifying and stopping it from further infecting your device. To do that, press Ctrl + Alt + Delete and open the task manager. Then, go to 'Processes' and check for any unfamiliar programs running. To confirm if it is a virus, search online.

How do I run a security check on my phone? ›

Open your device's Settings app. Tap Security. To check if a security update is available, tap Google Security checkup.

How can I clean my phone from viruses for free? ›

Open the Play Store app, tap your icon or avatar in the top right, and activate Play Protect in the menu. Install anti-malware software. An antivirus app is the best way to automatically clean your phone of viruses and malware. Plus it'll detect malicious strains to prevent future infections.


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