CVE-2017-1000230
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 · uneditedThe Snap7 Server version 1.4.1 can be crashed when the ItemCount field of the ReadVar or WriteVar functions of the S7 protocol implementation in Snap7 are provided with unexpected input, thus resulting in denial of service attack.
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 confidenceSnap7 Server version 1.4.1 contains a denial-of-service vulnerability in the S7 protocol implementation. The ReadVar and WriteVar functions fail to properly validate the ItemCount field when provided with unexpected input, causing the server to crash.
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= 1.4.1CVSS 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
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
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 if Snap7 Server is installedCheck for the presence of snap7 server components. On Linux, look for /usr/lib/libsnap7.so, /opt/snap7/bin/snap7-server, or check if the snap7-server process is running. On Windows, check for C:\Windows\System32\snap7.dll or the snap7-server service.Affected if Snap7 Server binaries or service are found on the system
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Determine installed Snap7 Server versionRun 'snap7-server -v' or 'snap7-server -version' if available. On Linux, check the library version with 'objdump -x /usr/lib/libsnap7.so | grep Version' or review the snap7 package version via dpkg/rpm. On Windows, right-click snap7.dll and view Properties > Details for file version.Affected if The version reported is 1.4.1
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Verify S7 server is actively runningCheck if the S7 protocol server is listening on the default TCP port 102 (or a configured port). Run 'netstat -an | grep 102' or 'ss -tlnp | grep 102' on Linux. On Windows, check via 'netstat -an | findstr 102' or review running services.Affected if The S7 server process is running and accepting connections on port 102 or another S7 port
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Confirm the ReadVar/WriteVar interface is exposedReview server configuration files or documentation to determine if the S7 ReadVar and WriteVar function calls are enabled. These are standard S7 protocol functions. Check any snap7 configuration for exposed S7 communication.Affected if S7 protocol communication is enabled and accessible to network clients or attackers
If Snap7 Server version 1.4.1 is installed and the S7 server is running with ReadVar/WriteVar functions exposed, the environment is affected by CVE-2017-1000230.
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 dataImplement proper input validation and bounds checking on the ItemCount field in the ReadVar and WriteVar functions to ensure the value is within expected ranges before processing, preventing the crash condition.
- Consultation2.0 h
- Implementation4.0 h
- Testing4.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2017-1000230 — 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-2017-1000230 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
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