Insufficient Entropy in libtpms

1) Insufficient Entropy

EUVDB-ID: #VU54502

Risk: Low

CVSSv3.1: 3.2 [CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-3505

CWE-ID: CWE-331 - Insufficient Entropy

Exploit availability: No

Description

The vulnerability allows a local user to decrypt data.

The vulnerability exists in the TPM 2 implementation, which returns 2048 bit keys with ~1984 bit strength due to a bug in the TCG specification. The bug is in the key creation algorithm in RsaAdjustPrimeCandidate(), which is called before the prime number check.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

libtpms: 0.5.2 - 0.7.8

External links

http://bugzilla.redhat.com/show_bug.cgi?id=1950046
http://github.com/stefanberger/libtpms/issues/183
http://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/NUCZX4S53TUNTSGTCRDNOQZV2V2RI4RJ/

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.