Amazon Linux AMI update for sendmail

Published: 2024-08-06

Risk	Medium
Patch available	YES
Number of vulnerabilities	1
CVE-ID	CVE-2021-3618
CWE-ID	CWE-346
Exploitation vector	Network
Public exploit	N/A
Vulnerable software Subscribe	Amazon Linux AMI Operating systems & Components / Operating system sendmail Operating systems & Components / Operating system package or component
Vendor	Amazon Web Services

Security Bulletin

This security bulletin contains one medium risk vulnerability.

1) Origin validation error

EUVDB-ID: #VU59319

Risk: Medium

CVSSv3.1: 6.4 [CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-3618

CWE-ID: CWE-346 - Origin Validation Error

Exploit availability: No

Description

The vulnerability allows a remote attacker to bypass implemented security restrictions.

The vulnerability exists due to a logic error in TLS implementation when handling different protocols but using compatible certificates, such as multi-domain or wildcard certificates. A remote attacker with ability to perform TCP/IP layer MitM attack can redirect traffic from one subdomain to another, resulting in a valid TLS session. This breaks the authentication of TLS and cross-protocol attacks may be possible where the behavior of one protocol service may compromise the other at the application layer.

This attack technique was dubbed ALPACA (application layer protocol content confusion attack).

Mitigation

Update the affected packages:

aarch64:
    sendmail-debuginfo-8.17.1-5.amzn2023.0.4.aarch64
    sendmail-milter-debuginfo-8.17.1-5.amzn2023.0.4.aarch64
    sendmail-debugsource-8.17.1-5.amzn2023.0.4.aarch64
    sendmail-milter-devel-8.17.1-5.amzn2023.0.4.aarch64
    sendmail-milter-8.17.1-5.amzn2023.0.4.aarch64
    sendmail-8.17.1-5.amzn2023.0.4.aarch64

noarch:
    sendmail-cf-8.17.1-5.amzn2023.0.4.noarch
    sendmail-doc-8.17.1-5.amzn2023.0.4.noarch

src:
    sendmail-8.17.1-5.amzn2023.0.4.src

x86_64:
    sendmail-debuginfo-8.17.1-5.amzn2023.0.4.x86_64
    sendmail-milter-debuginfo-8.17.1-5.amzn2023.0.4.x86_64
    sendmail-debugsource-8.17.1-5.amzn2023.0.4.x86_64
    sendmail-milter-8.17.1-5.amzn2023.0.4.x86_64
    sendmail-milter-devel-8.17.1-5.amzn2023.0.4.x86_64
    sendmail-8.17.1-5.amzn2023.0.4.x86_64

Vulnerable software versions

Amazon Linux AMI: All versions

sendmail: before 8.17.1-5

External links

http://alas.aws.amazon.com/AL2023/ALAS-2023-018.html

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.