CVE-2005-3376
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 Kaspersky 5.0.372 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 confidenceKaspersky AV 5.0.372 misidentifies file types by scanning for magic bytes rather than full content analysis. Attackers embed 'MZ' executable headers within files that appear to be BAT, HTML, or EML formats, causing the scanner to treat them as safe. These 'triple-headed' files bypass detection yet can still execute malicious payload when opened by end-user applications that ignore the misleading file extension.
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= 5.0.372CVSS 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 Kaspersky AV versionCheck installed Kaspersky Anti Virus version via Add/Remove Programs, the application's About dialog, or the kaspersky installation directory for version informationAffected if The installed version is exactly 5.0.372 (no other versions are affected)
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Confirm real-time file scanning is enabledOpen Kaspersky AV settings and verify that 'File Anti-Virus' or real-time scanning is turned on and set to scan files on accessAffected if Real-time scanning is active and set to scan files (the vulnerability exploits the scanning engine)
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Test for magic-byte-only detectionUsing a safe test file with an .html, .bat, or .eml extension that contains an MZ (0x4D5A) executable header at the beginning, attempt to open or run it through Kaspersky to see if it is flagged as maliciousAffected if Kaspersky does NOT detect the file as a virus/worm (indicating it relies only on magic byte/file extension analysis rather than full content inspection)
You are affected if Kaspersky Anti Virus version 5.0.372 is installed with file scanning enabled and it fails to detect files with embedded MZ headers masquerading as non-executable file types.
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 dataDeploy vendor patch from Kaspersky to address the magic byte detection flaw. Consider additional content-filtering controls at email gateways to detect and block multi-format attachments containing executable content.
- Consultation1.0 h
- Implementation2.0 h
- Testing2.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2005-3376 — 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-2005-3376 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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