Is my AV potentially giving over 100 false positives?

Understanding False Positives in Antivirus Scanning: A Case Study with Bitdefender

In today’s digital landscape, reliable antivirus protection is crucial for safeguarding our systems. However, even the most trusted security software can sometimes generate false positives—alerts that flag safe files as potentially malicious. This article examines a recent incident involving Bitdefender, highlighting the challenges of false positives and what users can do to navigate such situations.

A User’s Experience with Unexpected Antivirus Alerts

A user reported receiving approximately 100 notifications from Bitdefender, indicating that various files had been quarantined as “potentially unwanted items.” These notifications appeared concurrently with an attempt to download a file from a website they previously trusted, associated with a popular roguelike game called Dungeon Crawl Stone Soup (DCSS). Despite their trusted source, the user encountered an “infected webpage detected” warning, which prevented the download from proceeding.

The user observed that the files flagged by Bitdefender were commonly used and well-known programs such as MS Paint, NVIDIA installers, and even Windows Update executable files. Intriguingly, all these files had been marked as “Gen:Trojan.Heur.FU.yGZ@aGLZuBhi,” raising questions about whether their files had been compromised or if the antivirus software was mistakenly identifying safe files as threats.

Analysis and Considerations

1. Potential Causes of False Positives:
2. Antivirus software relies heavily on heuristics and pattern matching to identify threats. Sometimes, these methods can mistake legitimate files for malicious code, especially after recent software updates or algorithm changes.

3. Quarantining a large number of files simultaneously can indicate a “heuristic explosion,” where the software’s detection algorithms become overly sensitive, possibly due to recent updates or specific triggers.

4. Timing of the Alerts:

5. The user noted that the barrage of notifications coincided with the website block. It’s conceivable that the website was compromised or that Bitdefender detected suspicious activity, prompting it to flag multiple files.

6. Could Files Have Been Replaced or Altered?

7. While it’s possible that files could be replaced by malware, the likelihood is relatively low, especially for systems with good protection and recent scans. Confirming changes would involve comparing file hashes or using integrity verification tools.

8. Lessons for Users:

9. Do not panic immediately. Investigate the nature of the flagged files—look at the file paths, their origins, and whether they’re essential