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

Overview

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.

Affected

• openssl >= 1.0.2, < 1.0.2zg
• openssl >= 1.1.1, < 1.1.1t
• openssl >= 3.0.0, < 3.0.8
• endpoint_security < 7.2.40
• sslvpn < 3.2.1
• stormshield_network_security >= 2.7.0, < 2.7.11
• stormshield_network_security >= 2.8.0, < 3.7.34
• stormshield_network_security >= 3.8.0, < 3.11.22
• stormshield_network_security >= 4.0.0, < 4.3.16
• stormshield_network_security >= 4.4.0, < 4.6.3

Remediation

Upgrade past the affected range:

• openssl 3.0.8
• endpoint_security 7.2.40
• sslvpn 3.2.1
• stormshield_network_security 4.6.3