TCP middlebox reflection attack in FortiOS

1) Improper Verification of Source of a Communication Channel

EUVDB-ID: #VU67032

Risk: Medium

CVSSv3.1: 6.5 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2022-27491

CWE-ID: CWE-940 - Improper Verification of Source of a Communication Channel

Exploit availability: No

Description

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to improper verification of the communication channel source when handling TCP connections. A remote attacker can force the device to send "blocked page" HTML data to an arbitrary victim via specially crafted TCP requests and perform TCP Middlebox Reflection attack.

Successful exploitation of the vulnerability requires that at least one firewall policy has inspection mode set to flow-based (default) and at least one Security Profile is enabled (e.g. Web Filter, AntiVirus, IPS, DLP, Application Control, SSL, File filter).

Mitigation

Install updates from vendor's website.

Vulnerable software versions

FortiOS: 6.0.0 - 7.2.0

External links

http://fortiguard.fortinet.com/psirt/FG-IR-22-073

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.