Timing side-channel attack in RSA-PSK key exchange in GnuTLS

1) Information Exposure Through Timing Discrepancy

EUVDB-ID: #VU83316

Risk: Medium

CVSSv3.1: 4.2 [CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2023-5981

CWE-ID: CWE-208 - Information Exposure Through Timing Discrepancy

Exploit availability: No

Description

The vulnerability allows a remote attacker to perform timing attack.

The vulnerability exists due to the response times to malformed ciphertexts in RSA-PSK ClientKeyExchange differ from response times of ciphertexts with correct PKCS#1 v1.5 padding. A remote attacker can perform timing sidechannel attack in RSA-PSK key exchange.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

GnuTLS: 3.8.0 - 3.8.1

External links

http://gitlab.com/gnutls/gnutls/-/issues/1511
http://gnutls.org/security-new.html#GNUTLS-SA-2023-10-23
http://lists.gnupg.org/pipermail/gnutls-help/2023-November/004837.html

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.