CVE-2023-32737

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.

Weakness

The product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid.

Potential Mitigations

• Make fields transient to protect them from deserialization.
• An attempt to serialize and then deserialize a class containing transient fields will result in NULLs where the transient data should be. This is an excellent way to prevent time, environment-based, or sensitive variables from being carried over and used improperly.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/586.html

References

• https://cert-portal.siemens.com/productcert/html/ssa-313039.html
• https://cert-portal.siemens.com/productcert/html/ssa-313039.html