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amazonAmazonALAS-2024-2431
HistoryJan 19, 2024 - 1:51 a.m.

Medium: vsftpd

2024-01-1901:51:00
alas.aws.amazon.com
15
vsftpd
alpaca attack
cve-2021-3618
tls
protocol
security
update
amazon linux 2
package

7.4 High

CVSS3

Attack Vector

NETWORK

Attack Complexity

HIGH

Privileges Required

NONE

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

HIGH

Integrity Impact

HIGH

Availability Impact

NONE

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

7.4 High

AI Score

Confidence

Low

5.8 Medium

CVSS2

Access Vector

NETWORK

Access Complexity

MEDIUM

Authentication

NONE

Confidentiality Impact

PARTIAL

Integrity Impact

PARTIAL

Availability Impact

NONE

AV:N/AC:M/Au:N/C:P/I:P/A:N

0.001 Low

EPSS

Percentile

43.8%

Issue Overview:

ALPACA is an application layer protocol content confusion attack, exploiting TLS servers implementing different protocols but using compatible certificates, such as multi-domain or wildcard certificates. A MiTM attacker having access to victim’s traffic at the TCP/IP layer 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. (CVE-2021-3618)

Affected Packages:

vsftpd

Note:

This advisory is applicable to Amazon Linux 2 (AL2) Core repository. Visit this FAQ section for the difference between AL2 Core and AL2 Extras advisories.

Issue Correction:
Run yum update vsftpd to update your system.

New Packages:

aarch64:  
    vsftpd-3.0.2-25.amzn2.0.1.aarch64  
    vsftpd-sysvinit-3.0.2-25.amzn2.0.1.aarch64  
    vsftpd-debuginfo-3.0.2-25.amzn2.0.1.aarch64  
  
i686:  
    vsftpd-3.0.2-25.amzn2.0.1.i686  
    vsftpd-sysvinit-3.0.2-25.amzn2.0.1.i686  
    vsftpd-debuginfo-3.0.2-25.amzn2.0.1.i686  
  
src:  
    vsftpd-3.0.2-25.amzn2.0.1.src  
  
x86_64:  
    vsftpd-3.0.2-25.amzn2.0.1.x86_64  
    vsftpd-sysvinit-3.0.2-25.amzn2.0.1.x86_64  
    vsftpd-debuginfo-3.0.2-25.amzn2.0.1.x86_64  

Additional References

Red Hat: CVE-2021-3618

Mitre: CVE-2021-3618

7.4 High

CVSS3

Attack Vector

NETWORK

Attack Complexity

HIGH

Privileges Required

NONE

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

HIGH

Integrity Impact

HIGH

Availability Impact

NONE

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

7.4 High

AI Score

Confidence

Low

5.8 Medium

CVSS2

Access Vector

NETWORK

Access Complexity

MEDIUM

Authentication

NONE

Confidentiality Impact

PARTIAL

Integrity Impact

PARTIAL

Availability Impact

NONE

AV:N/AC:M/Au:N/C:P/I:P/A:N

0.001 Low

EPSS

Percentile

43.8%