Cybercriminals don’t need sophisticated exploits to wreak havoc. Many of the most damaging breaches come from ordinary-looking files. You know the type: Word documents, PDFs, spreadsheets, and images with funny memes. Each and every one of these is a great place to hide malicious code.

However, because these everyday files are critical to daily business operations, security tools often allow them through. Antivirus (AV), endpoint detection and response (EDR), and data loss prevention (DLP) solutions try to help, but they rely on detection. That’s a fatal flaw when attackers constantly modify their tactics to evade signatures and known rules.

Below, we’ll talk about the ten most common and dangerous hidden file threats that slip past traditional defenses on a regular basis. We’ll also discuss what your organization can do to stop them.

1. Malicious Macros in Office Files

Spreadsheets and Word documents with embedded macros remain a favorite delivery vehicle for attackers. While macros automate legitimate business processes, they can also launch ransomware, download remote payloads, or exfiltrate data once opened. Traditional tools often strip or block them outright, but that breaks business-critical workflows. 

Votiro advanced file sanitization (aka Content Disarm & Reconstruction aka CDR) ensures macros are preserved while hidden code is removed.

2. Weaponized PDFs

PDFs are trusted across industries for contracts, applications, and financial documents. But embedded scripts and links turn them into perfect malware carriers. A user only needs to open a PDF for the hidden payload to launch, bypassing AV tools that don’t recognize the new variant.

Votiro file sanitization uses AV as just one part of its threat detection, but goes further by implementing proactive, zero trust detection that doesn’t require known signatures. 

3. Image Files with Embedded Malware

From JPEGs to GIFs, images are common in email and collaboration tools. Attackers manipulate metadata or embed malicious code within seemingly harmless images. Since security tools often deprioritize image scanning, these threats are prime candidates for slipping malware into organizations unnoticed.

Votiro CDR catches sophisticated steganography attacks before they reach endpoints. 

4. Drive-By Downloads

Employees downloading research, templates, or data from the web risk pulling in malicious files disguised as legitimate resources. Compromised sites inject drive-by downloads that bypass traditional browser defenses and rely on outdated technology to catch them. Too often, that never happens.

With Votiro now part of Menlo Security, users gain the advantages of a secure enterprise browser solution PLUS zero-day malware prevention. 

5. Collaboration Tool File Sharing

Teams, Box, and similar platforms have become business lifelines. But they also spread infected files at lightning speed – both to internal users and third-party contractors. Because collaboration platforms operate inside the firewall, traditional defenses treat them as trusted. That trust makes it easier for hidden threats to propagate.

In this demonstration, you can see how Votiro CDR mitigates threats to collaboration in real-time.

6. Data Lake Ingestion

Financial institutions, insurers, and lenders collect massive volumes of customer-submitted files, including scans of IDs, pay stubs, tax documents, and dozens of other types of files. These uploads frequently land in data lakes for processing. If even one file is compromised, then malware can be activated when staff or automated systems open the file to process the data.

Votiro has the ability to scale to unique company needs, such as large file transfers and storage during mergers and acquisitions.

7. Email Attachments

The most well-known attack vector is still the most effective. Verizon reports that the majority of malware arrives via email. Attackers disguise malicious payloads as invoices, resumes, or reports, exploiting human trust in familiar formats. Even when security filters block some threats, zero-day or modified variants make it through.

Votiro CDR is especially suited for preventing malicious email attachments from reaching secure environments. No longer are companies reliant on outdated SEGs.

8. Supply Chain & Third-Party Uploads

Partners, vendors, and contractors frequently exchange files. Everything from contracts to compliance documents can be a necessary part of collaboration. Unfortunately, each of those uploads represents a potential Trojan horse. Even if your security is strong, a third party’s weak defenses can give an attacker an entry point.

For proof of how this common file security gap can cause damage beyond the initial target, look no further than the AT&T/Snowflake breach. 

9. Archive Files (ZIP, RAR, 7z)

Compressed files mask malicious payloads inside multiple layers. Attackers know that many AV and DLP solutions struggle with recursive scanning. The result? Dangerous executables or scripts are wrapped in a ZIP archive that seems safe until opened.

Votiro CDR is capable of sanitizing over 220+ file types, including archive, ZIP, and password-protected files.

10. AI-Enhanced and Zero-Day Malware in Files

AI is now used to automatically modify malware, creating endless permutations that detection-based tools don’t recognize. These files may look legitimate and sail past signatures, but they still carry dangerous code designed to evade traditional defenses.

With GenAI continuing to evolve and be adapted by organizations and threat actors alike, teams need a zero trust solution, like Votiro, to stay ahead of zero-moment attacks.

Why Traditional Security Misses These Threats

AV, EDR, DLP, and even DSPM play important roles. But they share critical limitations:

• Detection-based: They only stop what they recognize. Modified or zero-day threats slip through.
• Disruption-prone: They often block legitimate files to stay safe, slowing productivity.
• Fragmented: Each tool covers a piece of the problem, leaving blind spots that attackers exploit.

Files are central to business; blocking or quarantining them is not a viable strategy. What’s needed is a way to make every file safe before it reaches the user.

How to Stop Hidden File Threats with CDR

Instead of relying on detection, CDR assumes every file is a potential threat. CDR breaks each file down, removes unsafe and unknown elements, then rebuilds them from only known-good components – in just seconds, in real-time. 

Votiro Advanced CDR goes a significant step further by rebuilding files with safe macros and essential elements intact. This means that the files teams rely on remain fully functional – something that other CDR vendors cannot accomplish.

The Business Value of Proactive File Security

Stopping hidden file threats is more than just solving a cybersecurity problem. Done right, it’s a business enabler:

• Prevent breaches before they cost millions: Average breach costs now exceed $4.45M.
• Maintain customer trust: Clean, safe files mean sensitive data can’t be stolen or misused.
• Ensure compliance without friction: Regulations like GDPR, HIPAA, and PCI-DSS demand secure handling of files and PII.
• Keep productivity flowing: Employees and partners access the files they need instantly, without blockages or quarantines.
• Reduce SOC fatigue: Fewer false positives means teams focus on real threats.

How Votiro Makes Files Safe by Design

From macros to PDFs to AI-shaped malware, hidden file threats evade traditional tools and put organizations at risk. The solution is not to block files but to make them safe by design.

By adopting Votiro CDR, organizations can eliminate file-borne threats before they reach endpoints. The result: safer collaboration, streamlined compliance, and the freedom to use files without fear.

See how Votiro makes every file safe by booking a personalized demo today.