When using antivirus software like ClamXAV, it’s easy to assume that everything it flags is dangerous. That’s not always the case. Recently, there was an incident where ClamXAV flagged several large media files used for a documentary project. These weren’t malware—they were just big, complex, and slightly unusual files. The recovery process that followed involved a smart quarantine workflow and a bit of human detective work.
TLDR
ClamXAV mistakenly flagged large media files as suspicious. These files were not malware but triggered the antivirus due to their size and encoding. A well-planned quarantine and recovery process helped identify and restore the safe files. This incident shows how antivirus tools, while helpful, sometimes need human review.
What is ClamXAV?
ClamXAV is a security app for macOS. It scans your system for viruses, trojans, and other malicious code. It’s built on the ClamAV open-source engine.
It’s reliable, easy to use, and works quietly in the background. But like all tools, it isn’t perfect. Sometimes, it flags harmless stuff by mistake.
The Incident with the Media Files
A small creative agency was working on a video series. The files were huge—some close to 10 GB. Many had multiple audio and video layers encoded in special formats.
ClamXAV started to flag these files as “potentially unwanted.” Why? It thought the complex encoding patterns were suspicious. To be fair, malformed media files can sometimes hide threats. But in this case, it was just… art.
The flagged files were auto-quarantined. Panic followed. Projects were paused. Editors wondered if months of work had vanished.
Why Did ClamXAV Flag the Files?
Good question. There are a few possible reasons:
- File Size: Files larger than a specific threshold can be flagged during heuristics analysis.
- Encoding Complexity: Multiple codecs and layers confused the scan engine.
- Embedded Metadata: Some media files had odd metadata, possibly from older software.
In other words, it was a false positive. The antivirus was just doing its job—perhaps a little too well.
The Quarantine Feature in ClamXAV
Quarantine is like a digital jail. When ClamXAV finds something fishy, it moves it to a secure folder. This prevents the file from causing harm—assuming it’s actually harmful.
The good news? Files in quarantine aren’t deleted. They’re just tucked away safely.
How Quarantine Works:
- The scanner detects a suspicious item.
- The file is copied into the quarantine directory.
- The original is either moved or marked.
- You get a notification and options to delete, ignore, or restore.
Recovering the Files
Here’s where the Quarantine Recovery Workflow kicks in. It’s like being a digital detective. Here’s how the team got their media files back:
Step-by-Step Recovery:
- Step 1: They reviewed the quarantine list inside ClamXAV.
- Step 2: They checked file names and compared them with their project assets.
- Step 3: They selected a few smaller files and restored them to test.
- Step 4: They scanned the restored files using a second antivirus tool for verification.
- Step 5: Once confirmed safe, they restored the rest of the media files.
This process took a few hours but saved weeks of work that would have otherwise been lost.
Lessons Learned
This wasn’t just a scare—it was a valuable learning moment. Here’s what the team took away:
- Backup Regularly: Having a secondary copy of files would’ve made this incident less stressful.
- Whitelist Trusted Assets: For future projects, scanning files ahead and whitelisting safe patterns helps.
- Don’t Automatically Delete: Using quarantine rather than delete ensures you can recover false positives.
Making Antivirus Work for You
Antivirus tools are like watchdogs. They bark at anything unfamiliar. That’s good, but it can be annoying—especially when you know the “intruder” is a guest.
You can train your tools to be smarter:
- Adjust threshold settings to be less aggressive for known file types.
- Add exclusions for certain folders or extensions you work with often.
- Use secondary verification before removing files flagged as threats.
How to Prevent This From Happening Again
Once bitten, twice shy. Here are a few best practices to avoid another media-file meltdown:
1. Create a Safe Workspace
Keep your project files in a dedicated folder. Let ClamXAV know to ignore it unless manually triggered. This limits accidental quarantines.
2. Use Checksums
Before uploading or exporting large files, generate checksums (like MD5 or SHA). This way, if something goes wrong, you can test file integrity easily.
3. Run Scheduled Deep Scans
A weekly deep scan during off-hours helps catch threats without blindsiding you during working hours.
4. Make Use of Logging
ClamXAV logs show exactly what it scanned and why it flagged something. Keep logs enabled and learn to read them.
Final Thoughts
No one likes unnecessary scares. But tools like ClamXAV are still super helpful. The key is to understand how they work and how to respond when they trigger a false alarm.
In this case, having a smart response plan with a quarantine recovery workflow turned a potential disaster into just a funny story for the next team lunch.
So, the next time your antivirus cries wolf, take a breath. Open the logs, trust your backups, and remember: not all suspects are guilty.