Amazon Linux 2 : openssl11 (ALAS-2023-2097)

critical Nessus Plugin ID 177863

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Synopsis

The remote Amazon Linux 2 host is missing a security update.

Description

The version of openssl11 installed on the remote host is prior to 1.1.1g-12. It is, therefore, affected by a vulnerability as referenced in the ALAS2-2023-2097 advisory.

Issue summary: Processing some specially crafted ASN.1 object identifiers ordata containing them may be very slow.

Impact summary: Applications that use OBJ_obj2txt() directly, or use any ofthe OpenSSL subsystems OCSP, PKCS7/SMIME, CMS, CMP/CRMF or TS with no messagesize limit may experience notable to very long delays when processing thosemessages, which may lead to a Denial of Service.

An OBJECT IDENTIFIER is composed of a series of numbers - sub-identifiers -most of which have no size limit. OBJ_obj2txt() may be used to translatean ASN.1 OBJECT IDENTIFIER given in DER encoding form (using the OpenSSLtype ASN1_OBJECT) to its canonical numeric text form, which are thesub-identifiers of the OBJECT IDENTIFIER in decimal form, separated byperiods.

When one of the sub-identifiers in the OBJECT IDENTIFIER is very large(these are sizes that are seen as absurdly large, taking up tens or hundredsof KiBs), the translation to a decimal number in text may take a very longtime. The time complexity is O(n^2) with 'n' being the size of thesub-identifiers in bytes (*).

With OpenSSL 3.0, support to fetch cryptographic algorithms using names /identifiers in string form was introduced. This includes using OBJECTIDENTIFIERs in canonical numeric text form as identifiers for fetchingalgorithms.

Such OBJECT IDENTIFIERs may be received through the ASN.1 structureAlgorithmIdentifier, which is commonly used in multiple protocols to specifywhat cryptographic algorithm should be used to sign or verify, encrypt ordecrypt, or digest passed data.

Applications that call OBJ_obj2txt() directly with untrusted data areaffected, with any version of OpenSSL. If the use is for the mere purposeof display, the severity is considered low.

In OpenSSL 3.0 and newer, this affects the subsystems OCSP, PKCS7/SMIME,CMS, CMP/CRMF or TS. It also impacts anything that processes X.509certificates, including simple things like verifying its signature.

The impact on TLS is relatively low, because all versions of OpenSSL have a100KiB limit on the peer's certificate chain. Additionally, this onlyimpacts clients, or servers that have explicitly enabled clientauthentication.

In OpenSSL 1.1.1 and 1.0.2, this only affects displaying diverse objects,such as X.509 certificates. This is assumed to not happen in such a waythat it would cause a Denial of Service, so these versions are considerednot affected by this issue in such a way that it would be cause for concern,and the severity is therefore considered low. (CVE-2023-2650)

Tenable has extracted the preceding description block directly from the tested product security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

Solution

Run 'yum update openssl11' to update your system.

Plugin Details

Severity: Critical

ID: 177863

File Name: al2_ALAS-2023-2097.nasl

Version: 1.3

Type: local

Agent: unix

Family: Amazon Linux Local Security Checks

Published: 7/1/2023

Updated: 12/11/2024

Supported Sensors: Agentless Assessment, Continuous Assessment, Frictionless Assessment Agent, Frictionless Assessment AWS, Nessus Agent, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 4.4

CVSS v2

Risk Factor: High

Base Score: 7.8

Temporal Score: 5.8

Vector: CVSS2#AV:N/AC:L/Au:N/C:N/I:N/A:C

CVSS Score Source: CVE-2023-2650

CVSS v3

Risk Factor: Medium

Base Score: 6.5

Temporal Score: 5.7

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

CVSS v4

Risk Factor: Critical

Base Score: 9.3

Threat Score: 8.1

Threat Vector: CVSS:4.0/E:U

Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Vulnerability Information

CPE: p-cpe:/a:amazon:linux:openssl11, p-cpe:/a:amazon:linux:openssl11-debuginfo, p-cpe:/a:amazon:linux:openssl11-devel, p-cpe:/a:amazon:linux:openssl11-static, cpe:/o:amazon:linux:2, p-cpe:/a:amazon:linux:openssl11-libs

Required KB Items: Host/local_checks_enabled, Host/AmazonLinux/release, Host/AmazonLinux/rpm-list

Exploit Ease: No known exploits are available

Patch Publication Date: 6/21/2023

Vulnerability Publication Date: 3/21/2023

Reference Information

CVE: CVE-2023-2650

IAVA: 2023-A-0158-S

Detections

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