Can You Get a Virus from a PDF?

After seeking help from an IT professional, Marquisha learned her computer had a virus, which the professional tracked back to that PDF. While the PDF might have seemed harmless when she opened it, the virus put her personal and financial information at risk, and her system and digital identity could face greater attack in the future. This article will discuss PDFs, their associated threats, and how to reduce your risk when approaching new attachments so you never end up in Marquisha’s situation.

What is a PDF?

PDFs, or Portable Document Formats, are an easily accessible tool that individuals use to exchange and present documents to employees and clients regardless of the software, hardware, or Operating System (OS) they work on. PDFs can hold links, buttons, form fields, audio, video, and business logic. These documents preserve formatting and layout across devices and OSes while being smaller so you can store, transfer, and download information in a safer context. 

Enjoy advanced web and email security features like encryption and password protection that can safeguard sensitive data. Businesses need a reliable, professional document format to send to recipients. This formatting guarantees consistency, security, and accessibility.

You can also set permissions for different users and groups, giving you control over who can print, copy, and edit the content. This ensures that only authorized individuals perform specific actions on a PDF file. When sharing sensitive documents with a limited audience, these restrictions can provide extra document protection, keeping your confidential information safe while maintaining business integrity.

What is a Virus? Can a PDF Attachment Have a Virus?

PDFs are a beneficial technology with cybersecurity tools that keep documents relatively secure. However, malware can take various forms and manipulate PDFs to integrate email viruses that can exploit cybersecurity vulnerabilities once installed on a server. Cybercriminals turn to PDFs due to their popularity in digital environments.

Malicious PDF viruses can come in seemingly harmless images and documents that install malware on your server after a victim downloads the attachment. The hidden script can initiate malicious codes that exploit web and email security weaknesses to compromise other files and data. PDF readers like Adobe Reader and Acrobat have security patching issues that prevent them from being completely secure. You must exercise caution when opening files from untrusted, unknown sources to avoid installing malicious content.

In many instances, simply opening the PDF file is enough for the malware to initiate infections and exploit vulnerabilities that can harm your business’ productivity and operations. Therefore, while PDFs are one of the best ways to get and send files easily, you must remember to remain cautious when navigating PDFs to avoid downloading viruses, malicious links, and malware ransomware.

What Are the Most Common Types of PDF Viruses? What Are the Risks of Opening a Malicious PDF File?

PDF malware can take multiple forms, making it easier for hackers to disguise viruses and enter systems more easily. Here are the most common shapes that a virus will take:

• Javascript offers functionalities that can enhance a user’s experience. Unfortunately, cybercriminals can exploit misconfigurations to spread viruses and malicious scripts. These cybersecurity vulnerabilities permit threat actors to install malware on a server without the user’s knowledge once the victim opens the downloaded material. This can create issues such as sensitive data exposure, unauthorized access, and device damage. Users must check that all PDF files come from reputable sources and employ the latest security patches to mitigate risk.
• Multimedia Content like images, videos, and sound files can make PDFs more interactive and practical for specific audiences. However, multimedia can also be a vehicle for embedding harmful content into files that users need to open to view. Victims trigger malicious codes that can download malware and execute harm on a device. Users must avoid opening files from untrusted sources.
• Hyperlinks in a PDF provide more interactivity. Yet, they allow cybercriminals to get users to travel to phishing pages from which threat actors can steal login credentials and sensitive information that users input into the website. These websites permit data breach, unauthorized access, and system damage on a company server. Employees must inspect every link in a PDF file before opening it, especially from an unknown, untrusted source.

These email security risks can put businesses in a terrible position if they encounter such a threat. Understanding these forms of attack is essential to preparing your company for any issue that might head your employees’ way. Threat actors can use these above methods to execute any of the following cybersecurity attacks:

• PDF Trojans steal data from your machine and send it to the attacker so they can access your personal and banking information, photos, and crucial documents. Lurk Trojan is a type of threat that hijacks a user's device and obtains login credentials after installing itself and malware on a user’s device.
• PDF Malware focuses on destroying or changing information on your device by injecting ads into your browser or encrypting information. Then, in typical malware ransomware form, the cybercriminals will hold onto your data until you pay a ransom, usually in untraceable Bitcoin. Locky ransomware distributes itself through spam and phishing campaigns that enter a system through downloaded PDFs.
• Droppers focus on getting target users to download malicious files through PDFs that execute code on their browsers once they open a hyperlink. Bladabindi malware is a Remote Access Trojan (RAT) that contains malicious macros that install on a server and gain permissions without having direct contact with a device.

Here are a few more examples of dangerous virus attacks that can harm millions of victims if they are not aware of the risks they face when opening PDF files:

• Agent Tesla has been active since 2014 and delivers malicious attachments in phishing email attacks. This malware can steal data from mail clients, web browsers, and File Transfer Protocol (FTP) servers. It can also capture screenshots, videos, and Windows clipboard data. Cybercriminals can take the information they steal and sell it on the Dark Web. Agent Tesla promotes itself as a legitimate cybersecurity tool for managing your computer, but it focuses on targeting web applications for credential theft.
• AZORult has been in business since 2016 and delivers through phishing email attacks, infected websites, exploited cybersecurity toolkits, and dropper malware. AZORult steals information from compromised systems to sell on underground hacker forums, allowing hackers to steal browser data, user credentials, and cryptocurrency information.
• FormBook malware has existed since 2016 and is delivered as an attachment in phishing email attacks to steal information to advertise in hacking forums. FormBook uses keylogging attack methods to capture browser and email client passwords.

These detrimental PDF threat types can cause severe harm to a server, leaving organizations scrambling to recover after an attack. Consider employing various email security solutions to strengthen your business's email protection.

How Can I Protect My Server from PDF Email Viruses?

Your risk of infection revolves around what weaknesses are present in your PDF reader's cybersecurity tools. Here are a few email virus solutions we suggest you utilize to your advantage to mitigate threats and minimize future issues:

• Familiarize yourself with common phishing campaigns so you can quarantine emails you do not trust. If an unknown sender claims to be from a reputable organization or financial institution, avoid interacting with it. Contact the business separately through their official channels so you can verify whether or not the attachment is authentic. Such practices help you avoid encountering the latest phishing email threats and allow you to confirm your collaborators before an attack.
• Install Sender Policy Framework (SPF), DomainKeys Identified Mail (DKIM), and DMARC email authentication protocols as an extra verification form between you and the sender. With such web and email security, you can trust collaborators and avoid unreliable sources from accessing your files.
• Utilize a trusted PDF reader and update it regularly so all your files remain secure and capable of combating malicious activity. Adobe Acrobat Reader, the industry standard for viewing and working with PDFs, frequently releases cybersecurity updates that help protect users and their information.
• Run regular email virus scans on OSes with built-in antivirus software like Windows and macOS. Consider malware URL scanners, which can also check hyperlinks for malicious codes. Most PDF viruses require that victims open a file to execute the attack, so having antivirus software to warn you can keep you safe. Inspecting your system allows you to perform security patching on the latest web and email security risks to avoid exploitation.
• Encrypt your PDFs with passwords and digital signatures that protect sensitive information and prevent unauthorized individuals from copying or accessing your data. Set different, complex passwords for editing versus opening PDF files. Always utilize high-security passwords that are not easy for cybercriminals to identify. Digital signatures enhance security by keeping track of what aspects of a PDF someone has modified, maintaining integrity and authenticity for a business. Create signatures will be PDFCreator so you can verify user identities and protect against tampering and unauthorized modifications.
• Stay informed about the latest phishing emails, cybersecurity threats, and best practices for email security to minimize your chances of falling victim to malicious emails with PDF virus attachments. Sign up for our Behind the Shield cybersecurity newsletter to stay informed.

Engaging in these email security best practices is essential to protecting your contract, legal documents, and financial statements from cybercriminals who want to use your information.

Keep Learning How to Navigate PDF Files and Viruses

You can no longer trust a PDF at face value, as various malicious emails utilize PDFs as a form of attack. Businesses, clients, and employees must know when it is safe to open a file and how to do so without putting their information at risk. Countless phishing email attack victims have faced data loss, significant downtime, reputational damage, and worse impacts from opening malicious PDF files in the past. Only download PDFs from reliable sources and turn off any automatic download attachments that would permit malicious content to install itself immediately. Implement malware URL scanners, antivirus software, and frequent security patching to ensure your device remains malware-free.