Overview
About vulnerability
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.
Details
- Affected product:
- AlmaLinux 9.2 ESU , Alpine Linux 3.22 , CentOS 7 ELS , CentOS 8.4 ELS , CentOS 8.5 ELS , Debian 10 , Debian 10 ELS , Debian 11 , Debian 12 , Debian 13 , EL 10 , EL 7 , EL 8 , EL 9 , Ubuntu 16.04 , Ubuntu 16.04 ELS , Ubuntu 18.04 , Ubuntu 18.04 ELS , Ubuntu 20.04 , Ubuntu 22.04 , Ubuntu 24.04
- Affected packages:
- openssl @ 3.0.7 (+21 more)
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.