#VU84108 Covert Timing Channel in Mozilla NSS - CVE-2023-4421
Published: December 12, 2023
Vulnerability identifier: #VU84108
Vulnerability risk: Medium
CVSSv4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2023-4421
CWE-ID: CWE-385
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerable software:
Mozilla NSS
Mozilla NSS
Software vendor:
Mozilla
Mozilla
Description
The vulnerability allows a remote attacker to gain access to sensitive information.
The vulnerability exists due to NSS code used for checking PKCS#1 v1.5 was leaking information useful in mounting Bleichenbacher-like attacks. Both the overall correctness of the padding as well as the length of the encrypted message was leaking through timing side-channel. By sending large number of attacker-selected ciphertexts, the attacker would be able to decrypt a previously intercepted PKCS#1 v1.5 ciphertext (for example, to decrypt a TLS session that used RSA key exchange), or forge a signature using the victim's key.
Remediation
Install updates from vendor's website.