CVE-2005-3374
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedMultiple interpretation error in F-Prot 3.16c allows remote attackers to bypass virus scanning via a file such as BAT, HTML, and EML with an "MZ" magic byte sequence which is normally associated with EXE, which causes the file to be treated as a safe type that could still be executed as a dangerous file type by applications on the end system, as demonstrated by a "triple headed" program that contains EXE, EML, and HTML content, aka the "magic byte bug."
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceF-Prot 3.16c antivirus misidentifies file types by examining only magic bytes rather than analyzing full file content. Attackers embed 'MZ' EXE headers (0x4D 0x5A) into non-executable files like HTML, BAT, or EML, causing the scanner to classify them as safe executables while the files retain their original functionality when opened by end-user applications.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data= 3.16cCVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- High
- Authentication
- None
- Confidentiality
- Partial
- Integrity
- Partial
- Availability
- Partial
AV:N/AC:H/Au:N/C:P/I:P/A:P
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Verify F-Prot versionCheck the installed F-Prot Antivirus version by reviewing the program files or running 'fpcmd -v' or checking the program's About/Properties windowAffected if The installed version is exactly 3.16c (older versions before this release or later versions with content analysis fixes are not affected)
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Create test file with embedded MZ headerCreate a text file (e.g., .html, .bat, or .eml) and prepend the magic bytes 0x4D 0x5A (MZ) to the beginning of the file while keeping valid non-executable content after itAffected if The file is a non-executable format (HTML, BAT, EML) but contains the MZ header bytes at offset 0
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Scan the test file with F-ProtRun F-Prot Antivirus scan on the test file created in step 2 and examine the detection result or classificationAffected if F-Prot classifies the file as an executable, Trojan, or virus rather than recognizing it as its actual file type (HTML/BAT/EML)
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Compare scan result against file behaviorOpen the test file with its associated application (browser for HTML, command interpreter for BAT, or mail client for EML) to confirm the file still functions as intendedAffected if The file executes its original functionality (HTML renders, BAT runs commands, EML opens as email) despite F-Prot classifying it as an executable
If F-Prot version 3.16c is installed and it classifies files with embedded MZ headers in non-executable formats as executables rather than recognizing their actual type, the environment is affected by this vulnerability.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor dataUpdate F-Prot to a version that performs deep content inspection rather than relying solely on magic byte detection, or deploy additional endpoint protection that analyzes file behavior regardless of extension or header.
- Consultation4.0 h
- Implementation8.0 h
- Testing4.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $5,120.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2005-3374 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2005-3374 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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