Avast researchers have discovered cybercriminals using an old medium (PDFs) in a new--and dangerous--way.

PDFs have become synonymous with convenience and reliability, serving as the backbone for our document-sharing needs. Whether for work, school, or personal use, their ability to maintain formatting across various platforms has made them indispensable.  

Yet, beneath this undeniable utility lies a growing threat that many overlook: Avast researchers have discovered that PDFs are increasingly becoming the chosen vehicle for cybercriminals to distribute malware and execute scams. This shift towards exploiting such a common file format underscores the constantly shifting landscape of digital threats. 

Why PDFs are a hacker’s paradise 

The universal appeal of PDFs is exactly what makes them a prime target for cyber attacks: Their widespread use and inherent trust by users make them an ideal cover for malicious activities. Attackers exploit this trust, embedding malware or scams within these documents because they know we're more likely to open a PDF without suspicion.  

Moreover, many email security systems give a free pass to PDF attachments, unwittingly becoming accomplices to cybercriminals. This creates a false sense of security among users, who might not question the legitimacy of a PDF attachment, especially when it seems to come from a reputable source. 

The art of social engineering 

Social engineering is a master trick in the cybercriminal's playbook, leveraging human psychology to manipulate individuals into divulging confidential information or performing actions that compromise their security. These tactics are alarmingly effective, as they prey on natural human instincts like trust, fear, and urgency.  

For instance, our researchers detected a PDF disguised as a Netflix billing error, which prompts unsuspecting victims to inadvertently hand over their payment information. Or consider the lottery scam, where the thrill of a surprise windfall is used to blindside individuals into submitting personal details or financial information. These are not just random attempts; they are calculated and targeted strategies aimed at exploiting human psychology. 

The Malware Menace 

While deceptive scams are troubling enough, the embedding of sophisticated malware within PDFs adds a more sinister dimension to the threat landscape. This isn't about causing minor annoyances; malware like AgentTesla, DarkGate, and RemcosRat can infiltrate systems to steal sensitive information, monitor user actions, and even take complete control over affected devices.  

The transition from simple scams to these complex malware deliveries marks a significant escalation in cyber threats, demonstrating the lengths to which attackers will go to exploit the digital channels we've come to rely on. 

How to shield yourself from malicious PDFS 

In today's digital landscape, your best defense against cyber threats is a combination of knowledge and vigilance. Here are some essential tips to help you navigate the murky waters of PDF-related scams and protect your digital life: 

1. Boost your knowledge: Understand the tactics used by cybercriminals to stay one step ahead.
2. Stay alert: Remain vigilant for unsolicited or suspicious PDF files.
3. Verify sources: Always check the origin of a document before opening it, especially if it asks for personal or financial details.
4. Practice caution: Treat cybersecurity as a continuous practice, not just a one-time measure.
5. Educate yourself and others: Spread awareness about the risks associated with PDF files and how to avoid them.

Despite the grim outlook, there's a beacon of hope. Our efforts at Avast have led to the successful interception and blocking of over 10 million malicious PDF-based activities, safeguarding millions of users worldwide from potential harm. This achievement highlights the effectiveness of robust cybersecurity measures and the importance of ongoing vigilance. But the battle against cyber threats is not ours alone; it requires the active participation of every internet user. 

In the digital era, information is power. Staying informed about the latest cyber threats and protective measures is crucial in building a secure online environment for yourself and your loved ones. At Avast, we're committed to providing you with the tools and knowledge needed to navigate the cyber landscape safely. Together, by staying alert and informed, we can outsmart the cybercriminals and keep our digital domains secure.