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FreeBSD : curl -- TLS 1.3 session ticket proxy host mixup (d10fc771-958f-11eb-9c34-080027f515ea)

low Nessus Plugin ID 148517

Synopsis

The remote FreeBSD host is missing a security-related update.

Description

Daniel Stenberg reports :

Enabled by default, libcurl supports the use of TLS 1.3 session tickets to resume previous TLS sessions to speed up subsequent TLS handshakes.

When using a HTTPS proxy and TLS 1.3, libcurl can confuse session tickets arriving from the HTTPS proxy but work as if they arrived from the remote server and then wrongly 'short-cut' the host handshake. The reason for this confusion is the modified sequence from TLS 1.2 when the session ids would provided only during the TLS handshake, while in TLS 1.3 it happens post hand-shake and the code was not updated to take that changed behavior into account.

When confusing the tickets, a HTTPS proxy can trick libcurl to use the wrong session ticket resume for the host and thereby circumvent the server TLS certificate check and make a MITM attack to be possible to perform unnoticed.

This flaw can allow a malicious HTTPS proxy to MITM the traffic. Such a malicious HTTPS proxy needs to provide a certificate that curl will accept for the MITMed server for an attack to work - unless curl has been told to ignore the server certificate check.

Solution

Update the affected package.

See Also

https://curl.se/docs/CVE-2021-22890.html

http://www.nessus.org/u?b3a35da8

Plugin Details

Severity: Low

ID: 148517

File Name: freebsd_pkg_d10fc771958f11eb9c34080027f515ea.nasl

Version: 1.3

Type: local

Published: 4/14/2021

Updated: 1/4/2024

Supported Sensors: Nessus

Risk Information

VPR

Risk Factor: Low

Score: 2.2

CVSS v2

Risk Factor: Medium

Base Score: 4.3

Temporal Score: 3.4

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

CVSS Score Source: CVE-2021-22890

CVSS v3

Risk Factor: Low

Base Score: 3.7

Temporal Score: 3.4

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

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

Vulnerability Information

CPE: p-cpe:/a:freebsd:freebsd:curl, cpe:/o:freebsd:freebsd

Required KB Items: Host/local_checks_enabled, Host/FreeBSD/release, Host/FreeBSD/pkg_info

Exploit Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 4/10/2021

Vulnerability Publication Date: 3/31/2021

Reference Information

CVE: CVE-2021-22890