Vulnerability identifier: #VU16222

Vulnerability risk: Medium

CVSSv3.1: 7.3 [CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:H/E:P/RL:O/RC:C]

CVE-ID: CVE-2018-16869

CWE-ID: CWE-300

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
TLS
Web applications / Other software

Vendor: IETF

Description
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.

Mitigation
Install update from vendor's website.

Vulnerable software versions

TLS: 1.0 - 1.3

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External links
http://www.wisdom.weizmann.ac.il/~eyalro/project/cat/cat.pdf

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability. However, proof of concept for this vulnerability is available.