Weaponized Files: The Latest Cybersecurity Threat Explained

Weaponized files are files that have been injected with malware to compromise devices and steal data. Learn how it works and how to stop it.  

Written by Neko Papez
Published on Jul. 27, 2023
Weaponized Files: The Latest Cybersecurity Threat Explained
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The increasing menace of weaponized files presents a formidable cybersecurity challenge for enterprise companies. Attackers employ diverse file types, like images and PDFs, as vehicles to deliver malware and compromise devices and networks. Additionally, the technique of template injection allows adversaries to manipulate files and bypass detection mechanisms, creating a significant hurdle for traditional security solutions.

Weaponized Files Explained

Weaponized files is a new cybersecurity threat that involves injecting file types like images, PDFs and Word files with malware to bypass traditional security tools and compromise devices and networks once the file is opened. 

To effectively combat this evolving threat, organizations must embrace a security approach that transcends outdated detection-based technologies.


What Are Weaponized Files?

Data breaches have become more lucrative in recent years, incentivizing threat actors to find more creative ways to access and steal corporate or sensitive data. Due to an increased reliance on digital infrastructure, weaponized files have emerged as a preferred tool for cybercriminals aiming to breach and exploit organizational security. Weaponized files involves attackers leveraging various file formats to deliver malware and compromise devices and networks. They’re able to do this thanks to increased browser vulnerabilities due to unpatched security flaws, outdated browser extensions or plugins. 

Threat actors know that the web browser has become the most widely deployed enterprise app today, and they can launch weaponized file attacks on any size organization or industry from any part of the world. Recent reports reveal instances where threat actors have exploited image files, such as PNG, to target different government organizations. Just a few months ago, nation-state threat actors used password-protected files to bypass traditional security tools. Adversaries have also harnessed platforms like Google Cloud to distribute malware concealed within innocuous PDFs, effectively deceiving users.

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Weaponized File Example: Template Injection 

One particularly elusive technique employed by adversaries is template injection. This method exploits vulnerabilities in file formats like Microsoft Word, Excel and PowerPoint, enabling the user to embed resources. Through manipulation of the "Relationships" function within XML files, attackers insert URLs hosting malicious templates. These injected templates lay dormant until the file is opened, effectively evading traditional security solutions that primarily focus on detecting macros or other explicit indicators of threats. 

As an example, The Menlo Labs research team conducted an analysis of weaponized decoy documents utilizing template injection techniques. These attacks have gained popularity among adversaries due to their ability to evade traditional detection because they don’t reveal suspicious indicators until the malicious template is fetched. Frameworks like Empire and Phishery facilitate the creation of weaponized template injection documents — and other more malicious tools may still emerge. 

Template injection attacks will continue to rise, even being used to dynamically load exploits. This technique is particularly concerning as it employs the legacy URL reputation evasion (LURE) method, utilizing reputable websites to deliver malware, and enables the injection of malicious URLs to download and execute templates, constituting a living off the land (LotL) attack. 


How Weaponized Files Bypass Traditional Security Solutions 

The proliferation of weaponized files poses a formidable challenge to conventional detection-based security solutions. With an ever-expanding range of file types and the ability to camouflage malicious content within seemingly benign files, distinguishing between harmless and weaponized files becomes increasingly arduous. 

Adversaries employing template injection and other evasive techniques can easily bypass detection technologies, leaving organizations vulnerable. This false sense of security can lead employees to unknowingly interact with weaponized files, inadvertently jeopardizing organizational security.

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How to Combat Weaponized Files

To effectively combat the risks posed by weaponized files, organizations must shift away from only relying on traditional detection-based technologies. A strategic security approach is imperative, encompassing the adoption of prevention solutions that proactively identify and thwart malicious URLs, detect anomalous file behavior and provide real-time threat intelligence. 

Browser isolation technology has emerged as a powerful preventive measure. By isolating web browsing activities from the network and delivering only safe content to users, browser isolation effectively mitigates the risk of weaponized files and other evasive web-based threats.

By understanding the techniques employed by threat actors, such as template injection, organizations can enhance their ability to identify and prevent attacks utilizing weaponized files. It’s essential to implement a cyber defense strategy that combines proactive prevention solutions with detection and response capabilities to effectively safeguard enterprise technology environments from the threats posed by weaponized files.

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