Predictable Libgcrypt random number generator output in GnuPG

1) Libgcrypt weak encryption

EUVDB-ID: #VU327

Risk: Low

CVSSv4.0: 0.4 [CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear]

CVE-ID: CVE-2016-6313

CWE-ID: CWE-330 - Use of Insufficiently Random Values

Exploit availability: No

Description

The vulnerability allows a local user to decrypt data.

The vulnerability exists in the Libgcrypt library due to weak implementation of random number generator. A local user, who can obtain 4640 bits from random generator, can predict the next 160 bits of output.

Successful exploitation of this vulnerability may result in generation of weak encryption keys and may lead to sensitive information disclosure.

 

Mitigation

Install the latest version of the library: 1.5.6, 1.6.6 or 1.7.3.

Vulnerable software versions

Libgcrypt: 1.5.0 - 1.7.2

Oracle VM Server for x86: 3.3 - 3.4

Oracle Linux: 6 - 7

CPE2.3

• cpe:2.3:a:gnu:libgcrypt:1.5.0:*:*:*:*:*:*:*
• cpe:2.3:a:gnu:libgcrypt:1.5.1:*:*:*:*:*:*:*
• cpe:2.3:a:gnu:libgcrypt:1.5.2:*:*:*:*:*:*:*
• cpe:2.3:a:oracle:oracle_vm_server_for_x86:3.3:*:*:*:*:*:*:*
• cpe:2.3:a:oracle:oracle_vm_server_for_x86:3.4:*:*:*:*:*:*:*
• cpe:2.3:o:oracle:oracle_linux:6:*:*:*:*:*:*:*
• cpe:2.3:o:oracle:oracle_linux:7:*:*:*:*:*:*:*

External links

https://lists.gnupg.org/pipermail/gnupg-announce/2016q3/000395.html
https://www.oracle.com/technetwork/topics/security/ovmbulletinoct2016-3090547.html
https://www.oracle.com/technetwork/topics/security/linuxbulletinoct2016-3090545.html

Q & A

Can this vulnerability be exploited remotely?

No. This vulnerability can be exploited locally. The attacker should have authentication credentials and successfully authenticate on the system.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.