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Simatic S7 400 FirmwareOperating system · Siemens

CVE-2018-16556

HIGH · 7.5 CVSS v3.1 Published 2018-12-13
Fix available
A fix is available. Upgrade to 8.2.1 or later.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click

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 · unedited
A vulnerability has been identified in SIMATIC S7-400 CPU 412-1 DP V7 (All versions), SIMATIC S7-400 CPU 412-2 DP V7 (All versions), SIMATIC S7-400 CPU 414-2 DP V7 (All versions), SIMATIC S7-400 CPU 414-3 DP V7 (All versions), SIMATIC S7-400 CPU 414-3 PN/DP V7 (All versions < V7.0.3), SIMATIC S7-400 CPU 414F-3 PN/DP V7 (All versions < V7.0.3), SIMATIC S7-400 CPU 416-2 DP V7 (All versions), SIMATIC S7-400 CPU 416-3 DP V7 (All versions), SIMATIC S7-400 CPU 416-3 PN/DP V7 (All versions < V7.0.3), SIMATIC S7-400 CPU 416F-2 DP V7 (All versions), SIMATIC S7-400 CPU 416F-3 PN/DP V7 (All versions < V7.0.3), SIMATIC S7-400 CPU 417-4 DP V7 (All versions), SIMATIC S7-400 CPU 412-2 PN V7 (All versions < V7.0.3), SIMATIC S7-400 H V4.5 and below CPU family (incl. SIPLUS variants) (All versions), SIMATIC S7-400 H V6 CPU family (incl. SIPLUS variants) (All versions < V6.0.9), SIMATIC S7-400 PN/DP V6 and below CPU family (incl. SIPLUS variants) (All versions), SIMATIC S7-410 CPU family (incl. SIPLUS variants) (All versions < V8.2.1), SIPLUS S7-400 CPU 414-3 PN/DP V7 (All versions < V7.0.3), SIPLUS S7-400 CPU 416-3 PN/DP V7 (All versions < V7.0.3), SIPLUS S7-400 CPU 416-3 V7 (All versions), SIPLUS S7-400 CPU 417-4 V7 (All versions). Specially crafted packets sent to port 102/tcp via Ethernet interface, via PROFIBUS, or via Multi Point Interfaces (MPI) could cause the affected devices to go into defect mode. Manual reboot is required to resume normal operation. Successful exploitation requires an attacker to be able to send specially crafted packets to port 102/tcp via Ethernet interface, via PROFIBUS or Multi Point Interfaces (MPI). No user interaction and no user privileges are required to exploit the security vulnerability. The vulnerability could allow causing a denial of service condition of the core functionality of the CPU, compromising the availability of the system.

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 confidence

Denial of service vulnerability in Siemens SIMATIC S7-400 CPU family devices where specially crafted packets sent to port 102/tcp (S7comm protocol) via Ethernet, PROFIBUS, or MPI interfaces can cause the affected CPU to enter defect mode, requiring manual reboot to resume operation.

MitigationApply available vendor firmware updates; until patched, restrict network access to port 102/tcp using firewalls or network segmentation to prevent unauthenticated attackers from reaching the affected devices.

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
Simatic S7 400 FirmwareOperating system
Affected:<= v6.0
Simatic S7 400 Pn\/dp V7 FirmwareOperating system
Affected:all versions
Simatic S7 400h FirmwareOperating system
Affected:<= v4.5
Simatic S7 410 FirmwareOperating system
Affected:< 8.2.1
Simatic S7 400h V6 FirmwareOperating system
Affected:all versions

CVSS 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:3.1/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 checks

Work through these to decide whether this CVE applies to you.

  1. Identify the device model
    Access the PLC hardware configuration or device front panel to determine the exact model (e.g., S7-400, S7-400 Pn/dp, S7-400h, S7-410, or S7-400h V6). This information is visible on the CPU module label or can be retrieved via TIA Portal or STEP 7 under the device properties.
    Affected if The device is any model in the SIMATIC S7-400 family (S7-400, S7-400 Pn/dp V7, S7-400h, S7-410, or S7-400h V6).
  2. Determine the firmware version
    In STEP 7 or TIA Portal, go to the CPU properties and locate the firmware version field. Alternatively, use the 'Online -> Accessible Nodes' function or read the firmware version directly from the CPU module via the programming device. For S7-410 devices, the firmware version is displayed in the 'Online & Diagnostics' diagnostics view.
    Affected if The firmware version falls within any of these affected ranges: S7-400 <= v6.0, S7-400h <= v4.5, S7-410 < v8.2.1, or if the device is S7-400 Pn/dp V7 or S7-400h V6 (all versions of these two models are affected).
  3. Verify if port 102/tcp is exposed
    From a system on the same network segment, run a port scan targeting port 102/tcp against the IP address assigned to the PLC (e.g., using nmap -p 102 <PLC_IP> or netcat). Also check network firewall rules or switch port configurations to determine if port 102 is reachable from untrusted network segments.
    Affected if Port 102/tcp (S7comm) is open and accessible from any network segment that contains untrusted or attacker-controlled systems.
  4. Check interface connectivity
    Review the PLC hardware configuration in STEP 7 or TIA Portal to identify which interfaces are enabled (Ethernet (PN/DP), PROFIBUS, or MPI). Verify if these interfaces are connected to operational networks and whether they share the same network as the attacking station.
    Affected if Any of the Ethernet, PROFIBUS, or MPI interfaces are connected to networks accessible to unauthenticated users, making the S7comm service reachable.

A user is affected if their environment contains any SIMATIC S7-400 family CPU with a firmware version in the affected ranges (or any version of S7-400 Pn/dp V7/S7-400h V6) and port 102/tcp is reachable from an untrusted network segment.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 data
Upgrade available Upgrade to 8.2.1 or later
Fixed in 8.2.1
Interim mitigation

Apply available vendor firmware updates; until patched, restrict network access to port 102/tcp using firewalls or network segmentation to prevent unauthenticated attackers from reaching the affected devices.

Fix this in Simatic S7 400 Firmware Scoped from the published advisory
  • Consultation8.0 h
  • Implementation16.0 h
  • Testing12.0 h
  • Review / QA4.0 h
40.0 hours of engineering $7,000
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2018-16556 in production — separate from our analysis above.

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What this is

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.

What belongs here
  • 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