Vulnerability CVE-2018-6829

Vulnerability Name:

CVE-2018-6829 (CCN-138917)

Assigned:

2018-02-07

Published:

2018-02-07

Updated:

2020-01-15

Summary:

cipher/elgamal.c in Libgcrypt through 1.8.2, when used to encrypt messages directly, improperly encodes plaintexts, which allows attackers to obtain sensitive information by reading ciphertext data (i.e., it does not have semantic security in face of a ciphertext-only attack). The Decisional Diffie-Hellman (DDH) assumption does not hold for Libgcrypt's ElGamal implementation.

CVSS v3 Severity:

7.5 High (CVSS v3.1 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N)
6.6 Medium (Temporal CVSS v3.1 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N/E:U/RL:U/RC:R)

Exploitability Metrics:	Attack Vector (AV): Network Attack Complexity (AC): Low Privileges Required (PR): None User Interaction (UI): None
Scope:	Scope (S): Unchanged
Impact Metrics:	Confidentiality (C): High Integrity (I): None Availibility (A): None

5.3 Medium (CCN CVSS v3.1 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N)
4.7 Medium (CCN Temporal CVSS v3.1 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N/E:U/RL:U/RC:R)

Exploitability Metrics:	Attack Vector (AV): Network Attack Complexity (AC): Low Privileges Required (PR): None User Interaction (UI): None
Scope:	Scope (S): Unchanged
Impact Metrics:	Confidentiality (C): Low Integrity (I): None Availibility (A): None

CVSS v2 Severity:

5.0 Medium (CVSS v2 Vector: AV:N/AC:L/Au:N/C:P/I:N/A:N)

Exploitability Metrics:	Access Vector (AV): Network Access Complexity (AC): Low Authentication (Au): None
Impact Metrics:	Confidentiality (C): Partial Integrity (I): None Availibility (A): None

5.0 Medium (CCN CVSS v2 Vector: AV:N/AC:L/Au:N/C:P/I:N/A:N)

Exploitability Metrics:	Access Vector (AV): Network Access Complexity (AC): Low Athentication (Au): None
Impact Metrics:	Confidentiality (C): Partial Integrity (I): None Availibility (A): None

Vulnerability Type:

CWE-327

Vulnerability Consequences:

Obtain Information

References:

Source: MITRE
Type: CNA
CVE-2018-6829

Source: XF
Type: UNKNOWN
libgcrypt-cve20186829-info-disc(138917)

Source: MISC
Type: Third Party Advisory
https://github.com/weikengchen/attack-on-libgcrypt-elgamal

Source: MISC
Type: Exploit, Third Party Advisory
https://github.com/weikengchen/attack-on-libgcrypt-elgamal/wiki

Source: CCN
Type: pipermail Mailing list, Wed Feb 7 09:14:46 CET 2018
Attack on libgcrypt's ElGamal Encryption with Proof of Concept (PoC)

Source: MISC
Type: Issue Tracking, Third Party Advisory
https://lists.gnupg.org/pipermail/gcrypt-devel/2018-February/004394.html

Source: CCN
Type: Libgcrypt Web site
The GNU Privacy Guard

Source: CCN
Type: Oracle CPUJan2020
Oracle Critical Patch Update Advisory - January 2020

Source: MISC
Type: UNKNOWN
https://www.oracle.com/security-alerts/cpujan2020.html

Vulnerable Configuration:

Configuration 1:

cpe:/a:gnupg:libgcrypt:*:*:*:*:*:*:*:* (Version <= 1.8.2)

Configuration CCN 1:

cpe:/a:gnupg:libgcrypt:1.8.2:*:*:*:*:*:*:*

AND

cpe:/a:oracle:communications_interactive_session_recorder:6.1:*:*:*:*:*:*:*

OR cpe:/a:oracle:communications_interactive_session_recorder:6.2:*:*:*:*:*:*:*

OR cpe:/a:oracle:communications_interactive_session_recorder:6.0:*:*:*:*:*:*:*

Denotes that component is vulnerable

Oval Definitions

Definition ID	Class	Title	Last Modified
oval:com.ubuntu.artful:def:20186829000	V	CVE-2018-6829 on Ubuntu 17.10 (artful) - medium.	2018-02-07
oval:com.ubuntu.bionic:def:201868290000000	V	CVE-2018-6829 on Ubuntu 18.04 LTS (bionic) - medium.	2018-02-07
oval:com.ubuntu.bionic:def:20186829000	V	CVE-2018-6829 on Ubuntu 18.04 LTS (bionic) - medium.	2018-02-07
oval:com.ubuntu.xenial:def:201868290000000	V	CVE-2018-6829 on Ubuntu 16.04 LTS (xenial) - medium.	2018-02-07
oval:com.ubuntu.trusty:def:20186829000	V	CVE-2018-6829 on Ubuntu 14.04 LTS (trusty) - medium.	2018-02-07
oval:com.ubuntu.xenial:def:20186829000	V	CVE-2018-6829 on Ubuntu 16.04 LTS (xenial) - medium.	2018-02-07

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