Fortinet Fortigate Curl and libcurl CVE-2023-38545 and CVE-2023-38546 vulnerabilities (FG-IR-23-385)

critical Nessus Plugin ID 192236

Language:

Synopsis

Fortinet Firewall is missing one or more security-related updates.

Description

The version of Fortigate installed on the remote host is prior to tested version. It is, therefore, affected by multiple vulnerabilities as referenced in the FG-IR-23-385 advisory.

- This flaw makes curl overflow a heap based buffer in the SOCKS5 proxy handshake. When curl is asked to pass along the host name to the SOCKS5 proxy to allow that to resolve the address instead of it getting done by curl itself, the maximum length that host name can be is 255 bytes. If the host name is detected to be longer, curl switches to local name resolving and instead passes on the resolved address only. Due to this bug, the local variable that means let the host resolve the name could get the wrong value during a slow SOCKS5 handshake, and contrary to the intention, copy the too long host name to the target buffer instead of copying just the resolved address there. The target buffer being a heap based buffer, and the host name coming from the URL that curl has been told to operate with. (CVE-2023-38545)

- CVE-2023-38545 is a heap-based buffer overflow vulnerability in the SOCKS5 proxy handshake in libcurl and curl. When curl is given a hostname to pass along to a SOCKS5 proxy that is greater than 255 bytes in length, it will switch to local name resolution in order to resolve the address before passing it on to the SOCKS5 proxy. However, due to a bug introduced in 2020, this local name resolution could fail due to a slow SOCKS5 handshake, causing curl to pass on the hostname greater than 255 bytes in length into the target buffer, leading to a heap overflow. The advisory for CVE-2023-38545 gives an example exploitation scenario of a malicious HTTPS server redirecting to a specially crafted URL. While it might seem that an attacker would need to influence the slowness of the SOCKS5 handshake, the advisory states that server latency is likely slow enough to trigger this bug. (CVE-2023-38545)

- This flaw allows an attacker to insert cookies at will into a running program using libcurl, if the specific series of conditions are met. libcurl performs transfers. In its API, an application creates easy handles that are the individual handles for single transfers. libcurl provides a function call that duplicates en easy handle called [curl_easy_duphandle](https://curl.se/libcurl/c/curl_easy_duphandle.html). If a transfer has cookies enabled when the handle is duplicated, the cookie-enable state is also cloned - but without cloning the actual cookies. If the source handle did not read any cookies from a specific file on disk, the cloned version of the handle would instead store the file name as `none` (using the four ASCII letters, no quotes). Subsequent use of the cloned handle that does not explicitly set a source to load cookies from would then inadvertently load cookies from a file named `none` - if such a file exists and is readable in the current directory of the program using libcurl. And if using the correct file format of course.
(CVE-2023-38546)

- CVE-2023-38546 is a cookie injection vulnerability in the curl_easy_duphandle(), a function in libcurl that duplicates easy handles. When duplicating an easy handle, if cookies are enabled, the duplicated easy handle will not duplicate the cookies themselves, but would instead set the filename to none.' Therefore, when the duplicated easy handle is subsequently used, if a source was not set for the cookies, libcurl would attempt to load them from the file named none' on the disk. This vulnerability is rated low, as the various conditions required for exploitation are unlikely. (CVE-2023-38546)

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

Solution

Upgrade to Fortigate version 7.0.14 / 7.2.7 / 7.4.2 or later.

Plugin Details

Severity: Critical

ID: 192236

File Name: fortigate_FG-IR-23-385.nasl

Version: 1.6

Type: local

Family: Firewalls

Published: 3/19/2024

Updated: 10/30/2024

Supported Sensors: Nessus

Risk Information

VPR

Risk Factor: High

Score: 7.4

CVSS v2

Risk Factor: Critical

Base Score: 10

Temporal Score: 7.8

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

CVSS Score Source: CVE-2023-38545

CVSS v3

Risk Factor: Critical

Base Score: 9.8

Temporal Score: 8.8

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

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

Vulnerability Information

CPE: cpe:/o:fortinet:fortios

Required KB Items: Host/Fortigate/model, Host/Fortigate/version

Exploit Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 12/20/2023

Vulnerability Publication Date: 11/14/2023

Reference Information

CVE: CVE-2023-38545, CVE-2023-38546

Detections

Analytics