CVE-2008-5543
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 · uneditedSymantec AntiVirus (SAV) 10, when Internet Explorer 6 or 7 is used, allows remote attackers to bypass detection of malware in an HTML document by placing an MZ header (aka "EXE info") at the beginning, and modifying the filename to have (1) no extension, (2) a .txt extension, or (3) a .jpg extension, as demonstrated by a document containing a CVE-2006-5745 exploit.
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 confidenceSymantec AntiVirus 10 fails to detect malware embedded in HTML documents when those documents have an MZ (DOS/Windows executable) header placed at the beginning and use deceptive file extensions (.txt, .jpg, or no extension). Internet Explorer 6/7 still processes the embedded executable content (such as CVE-2006-5745 exploits), allowing remote attackers to bypass antivirus detection.
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= 10.0CVSS 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
- M
- Authentication
- None
- Confidentiality
- Complete
- Integrity
- Complete
- Availability
- Complete
AV:N/AC:M/Au:N/C:C/I:C/A:C
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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Identify installed Symantec AntiVirus versionOpen Symantec AntiVirus, go to Help > About, or run 'symantec -version' from command line. Alternatively, check Add/Remove Programs for 'Symantec AntiVirus' entry.Affected if The version listed is exactly 10.0 (or 10.0.x)
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Confirm Internet Explorer version in useOpen Internet Explorer, then go to Help > About Internet Explorer. Alternatively, check the executable path at %ProgramFiles%\Internet Explorer\iexplore.exeAffected if The installed Internet Explorer version is 6.0 or 7.0
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Check if real-time scanning handles file extension spoofingReview Symantec AntiVirus 10.0 scan settings under Configure > Scan Options. Look for 'Scan emails' and 'Scan all files' settings, and verify if content-type based scanning is enabled.Affected if Real-time scanning is enabled but set to rely primarily on file extension for detection (default configuration)
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Verify HTML file handling behaviorCreate a test file with an MZ header (e.g., small valid .exe) renamed to .txt or .jpg. Attempt to open with Internet Explorer 6/7 to observe if it attempts to execute or process the embedded content.Affected if IE 6/7 processes the embedded executable content within the HTML file despite the deceptive extension
You are affected if Symantec AntiVirus version 10.0 is installed and the system runs Internet Explorer 6 or 7, allowing HTML files with MZ headers and deceptive extensions to bypass antivirus detection.
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 dataUpgrade from Symantec AntiVirus 10 to a current supported version with updated scanning engine, and migrate away from Internet Explorer 6/7 to modern browsers that have stricter content handling.
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 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 $5,600.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2008-5543 — 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-2008-5543 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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A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.
- 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
- No spam, self-promotion, credentials, or personal data