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Deserialization of Untrusted DataWeakness · CWE-502

CVE-2023-32737

MEDIUM · 6.3 CVSS v3.1 Published 2024-07-09
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
63/100
Remediation priority · Elevated

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 STEP 7 Safety V18 (All versions < V18 Update 2). Affected applications do not properly restrict the .NET BinaryFormatter when deserializing user-controllable input. This could allow an attacker to cause a type confusion and execute arbitrary code within the affected application. This is the same issue that exists for .NET BinaryFormatter https://docs.microsoft.com/en-us/visualstudio/code-quality/ca2300.

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 · moderate confidence

SIMATIC STEP 7 Safety V18 uses the deprecated .NET BinaryFormatter to deserialize user-controllable input without proper type restrictions. BinaryFormatter is inherently unsafe because it can deserialize arbitrary .NET types, allowing attackers to craft malicious serialized payloads that execute arbitrary code through type confusion during deserialization.

MitigationUpgrade to SIMATIC STEP 7 Safety V18 Update 2 or later, which removes the vulnerable BinaryFormatter usage. If immediate patching is not possible, restrict network exposure and verify the integrity of project files before opening them.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

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
Local
Complexity
High
Privileges
High
User interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:H/PR:H/UI:R/S:U/C:H/I:H/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 installed STEP 7 Safety version
    Open SIMATIC Manager or the product's About dialog. Navigate to Help > About in STEP 7 (TIA Portal) or check Programs and Features for 'SIMATIC STEP 7 Safety V18' entry which shows the installed version and update level.
    Affected if Version shows V18 without Update 2 or later (e.g., only V18, V18 SP1, or V18 Update 1)
  2. Verify BinaryFormatter usage in project deserialization
    Examine STEP 7 Safety project files (typically .s7p, .zap16, or related project archives) that the application opens and deserializes. If project files from untrusted sources can be opened, the BinaryFormatter deserialization path is reachable.
    Affected if Users open project files received from external or untrusted sources without verifying integrity first
  3. Check for presence of vulnerable BinaryFormatter code
    If access to the application installation directory is available, inspect the SIMATIC STEP 7 Safety binaries for BinaryFormatter usage. Search for 'BinaryFormatter' or 'System.Runtime.Serialization.Formatters.Binary' references in the installed DLLs using a tool likestrings or a .NET disassembler.
    Affected if BinaryFormatter classes are found in the STEP 7 Safety V18 installation binaries prior to Update 2
  4. Review project file handling configuration
    Check Windows Event Viewer and application logs for any deserialization errors or warnings when opening project files. Also verify if any custom safeguards or antivirus solutions are scanning project files before TIA Portal loads them.
    Affected if Project files are processed without integrity validation or malware scanning before deserialization

A user is affected if SIMATIC STEP 7 Safety V18 is installed without Update 2 or later AND users open project files from external or untrusted sources, allowing malicious BinaryFormatter payloads to be deserialized.

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.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade to SIMATIC STEP 7 Safety V18 Update 2 or later, which removes the vulnerable BinaryFormatter usage. If immediate patching is not possible, restrict network exposure and verify the integrity of project files before opening them.

Recommended fix High confidence

SIMATIC STEP 7 Safety V18 Update 2

  1. Identify the current installed version of SIMATIC STEP 7 Safety V18
  2. Navigate to the Siemens Industry Online Support portal and locate SIMATIC STEP 7 Safety V18
  3. Download SIMATIC STEP 7 Safety V18 Update 2 or later
  4. Run the installer and follow the on-screen prompts to apply the update
  5. Verify the installed version shows V18 Update 2 or later after installation

Generated from the published advisory — verify against the referenced sources before acting.

Have this fixed Scoped from the published advisory
  • Consultation4.0 h
  • Implementation3.0 h
  • Testing6.0 h
  • Review / QA2.0 h
15.0 hours of engineering $2,600
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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-2023-32737 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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