Detections
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Amazon Linux 2 : dhcp (ALAS-2021-1654)

high Nessus Plugin ID 150970

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Synopsis

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

Description

The version of dhcp installed on the remote host is prior to 4.2.5-77. It is, therefore, affected by a vulnerability as referenced in the ALAS2-2021-1654 advisory.

 - In ISC DHCP 4.1-ESV-R1 -> 4.1-ESV-R16, ISC DHCP 4.4.0 -> 4.4.2 (Other branches of ISC DHCP (i.e., releases in the 4.0.x series or lower and releases in the 4.3.x series) are beyond their End-of-Life (EOL) and no longer supported by ISC. From inspection it is clear that the defect is also present in releases from those series, but they have not been officially tested for the vulnerability), The outcome of encountering the defect while reading a lease that will trigger it varies, according to: the component being affected (i.e., dhclient or dhcpd) whether the package was built as a 32-bit or 64-bit binary whether the compiler flag -fstack-protection-strong was used when compiling In dhclient, ISC has not successfully reproduced the error on a 64-bit system. However, on a 32-bit system it is possible to cause dhclient to crash when reading an improper lease, which could cause network connectivity problems for an affected system due to the absence of a running DHCP client process. In dhcpd, when run in DHCPv4 or DHCPv6 mode: if the dhcpd server binary was built for a 32-bit architecture AND the -fstack-protection-strong flag was specified to the compiler, dhcpd may exit while parsing a lease file containing an objectionable lease, resulting in lack of service to clients. Additionally, the offending lease and the lease immediately following it in the lease database may be improperly deleted. if the dhcpd server binary was built for a 64-bit architecture OR if the -fstack-protection-strong compiler flag was NOT specified, the crash will not occur, but it is possible for the offending lease and the lease which immediately followed it to be improperly deleted. (CVE-2021-25217)

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 dhcp' to update your system.

See Also

https://alas.aws.amazon.com/AL2/ALAS-2021-1654.html

https://access.redhat.com/security/cve/CVE-2021-25217

Plugin Details

Severity: High

ID: 150970

File Name: al2_ALAS-2021-1654.nasl

Version: 1.4

Type: local

Agent: unix

Published: 6/23/2021

Updated: 12/12/2023

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

Risk Information

VPR

Risk Factor: Medium

Score: 5.2

CVSS v2

Risk Factor: Low

Base Score: 3.3

Temporal Score: 2.6

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

CVSS Score Source: CVE-2021-25217

CVSS v3

Risk Factor: High

Base Score: 7.4

Temporal Score: 6.7

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

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

Vulnerability Information

CPE: p-cpe:/a:amazon:linux:dhclient, p-cpe:/a:amazon:linux:dhcp, p-cpe:/a:amazon:linux:dhcp-common, p-cpe:/a:amazon:linux:dhcp-debuginfo, p-cpe:/a:amazon:linux:dhcp-devel, p-cpe:/a:amazon:linux:dhcp-libs, cpe:/o:amazon:linux:2

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

Exploit Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 6/16/2021

Vulnerability Publication Date: 5/26/2021

Reference Information

CVE: CVE-2021-25217

ALAS: 2021-1654

IAVB: 2021-B-0032-S