# Hitachi Energy GMS600 RSA decryption timing attack

Published: 2026-05-21 · Severity: routine · Sectors: manufacturing
Canonical: https://vorant.io/reports/7c4d9890-3b3a-5cc7-88d2-510f6307befd/hitachi-energy-gms600-rsa-decryption-timing-attack

> OpenSSL timing-based side-channel vulnerability in GMS600 1.3.0–1.3.1 allows plaintext recovery via Bleichenbacher-style attack.

Hitachi Energy GMS600 versions 1.3.0 and 1.3.1 contain CVE-2022-4304, a timing-based side-channel vulnerability in the bundled OpenSSL component affecting RSA decryption across all padding modes (PKCS#1 v1.5, RSA-OAEP, RSA-SVE). An attacker who observes a genuine TLS connection can send a large number of trial decryption messages to the target server, measuring response times to infer the pre-master secret and subsequently decrypt the application data from the original connection. This is a variant of the Bleichenbacher attack exploiting observable timing discrepancies in RSA processing.

The vulnerability is rated CWE-203 (Observable Discrepancy). GMS600 is a control system product deployed worldwide in critical manufacturing. Affected versions are 1.3.0 and 1.3.1; remediation is to upgrade to version 1.3.2. The advisory does not indicate active exploitation in the wild. Defenders should prioritize patching exposed instances and apply general mitigation: network segmentation, ingress IP allowlisting, rate limiting, and isolation of process control networks from the internet.

## Mentioned in this report

- Vulnerabilities: CVE-2022-4304

Source reporting: https://www.cisa.gov/news-events/ics-advisories/icsa-26-141-01

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