Cache Attacks in TLS - CVE-2018-19608
Published: December 4, 2018 / Updated: February 11, 2019
Vulnerability identifier: #VU16220
CSH Severity: Medium
CVSS v4: 8.3 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2018-19608
CWE-ID: CWE-300
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to perform a downgrade attack on the server and decrypt private keys on the target system.
The vulnerability exists due to a core weakness in TLS that relates to the handshaking of the session key which is used within the tunnel during parallelisation of thousands of oracle queries that occurs using a cluster of TLS servers which share the same public key certificate. A remote attacker can mount a microarchitectural side channel attack against a vulnerable implementation, obtain a network man-in-the-middle position, obtain the relevant data to sign and trigger the victim server to decrypt ciphertexts chosen by the adversary to perform a downgrade attack.
The vulnerability exists due to a core weakness in TLS that relates to the handshaking of the session key which is used within the tunnel during parallelisation of thousands of oracle queries that occurs using a cluster of TLS servers which share the same public key certificate. A remote attacker can mount a microarchitectural side channel attack against a vulnerable implementation, obtain a network man-in-the-middle position, obtain the relevant data to sign and trigger the victim server to decrypt ciphertexts chosen by the adversary to perform a downgrade attack.
Affected software
TLS
mbedtls (Alpine package)
mbedtls
Fedora
mbedtls (Alpine package)
mbedtls
Fedora
How to mitigate CVE-2018-19608
Install update from vendor's website.
mbedtls (Alpine package) - update to 2.14.1-r0
mbedtls - addressed in versions 2.7.8-1.el6, 2.7.8-1.el7, 2.14.1-1.fc28, 2.14.1-1.fc29
mbedtls - addressed in versions 2.7.8-1.el6, 2.7.8-1.el7, 2.14.1-1.fc28, 2.14.1-1.fc29