ICSA-23-222-09: Siemens SIMATIC

CISA's summary

Summary: Several SIMATIC products are affected by a timing based side channel vulnerability in the OpenSSL RSA Decryption (CVE-2023-4304), as disclosed on 2023-02-07 at https://www.openssl.org/news/secadv/20230207.txt. Siemens has released new versions for several affected products and recommends to update to the latest versions. Siemens recommends specific countermeasures for products where fixes are not, or not yet available.

Products, as the advisory lists them

DeSpy has not checked any unit, hardware revision or firmware.

Vulnerabilities in this advisory

• CVE-2022-4304 — CVE-2022-4304 · CWE-326

  A timing based side channel exists in the OpenSSL RSA Decryption implementation which could be sufficient to recover a plaintext across a network in a Bleichenbacher style attack. To achieve a successful decryption an attacker would have to be able to send a very large number of trial messages for decryption. The vulnerability affects all RSA padding modes: PKCS#1 v1.5, RSA-OEAP and RSASVE. For example, in a TLS connection, RSA is commonly used by a client to send an encrypted pre-master secret to the server. An attacker that had observed a genuine connection between a client and a server could use this flaw to send trial messages to the server and record the time taken to process them. After a sufficiently large number of messages the attacker could recover the pre-master secret used for the original connection and thus be able to decrypt the application data sent over that connection.

Acknowledgments, as the advisory lists them

• Siemens: reporting this vulnerability to CISA.

The advisory's legal notice

The use of Siemens Security Advisories is subject to the terms and conditions listed on: https://www.siemens.com/productcert/terms-of-use.

Sources

• The advisory at cisa.gov
• The CSAF document (JSON)

DeSpy's copy of this version is dated 2026-09-28.