MitM attack in Fortinet Forticlient

1) Improper validation of certificate with host mismatch

EUVDB-ID: #VU47108

Risk: High

CVSSv4.0: 8 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:U/U:Amber]

CVE-ID: N/A

CWE-ID: CWE-297 - Improper Validation of Certificate with Host Mismatch

Exploit availability: No

Description

The vulnerability allows a remote attacker to perform a MitM attack.

The vulnerability exists in FortiClient SSL-VPN client due to the application does not properly validate server certificates and checks only if the certificate was issued by a trusted CA or Fortinet itself. A remote attacker can supply a certificate, issued to a different Fortigate router and perform a Man-in-the-Middle attack.

Successful exploitation of the vulnerability may allow an attacker to intercept and descrypt all traffic, protected with Fortinet SSL-VPN.

Mitigation

Cybersecurity Help is currently unaware of any official solution to address this vulnerability.

Vulnerable software versions

Fortinet FortiClient for Windows: 0 - 6.4.0

CPE2.3

• cpe:2.3:a:fortinet:fortinet_forticlient:0:*:*:*:*:*:*:*
• cpe:2.3:a:fortinet:fortinet_forticlient:1.0.5:*:*:*:*:*:*:*
• cpe:2.3:a:fortinet:fortinet_forticlient:1.2.5:*:*:*:*:*:*:*
• cpe:2.3:a:fortinet:fortinet_forticlient:4.0.2:*:*:*:*:*:*:*
• cpe:2.3:a:fortinet:fortinet_forticlient:4.1.0:*:*:*:*:*:*:*
• cpe:2.3:a:fortinet:fortinet_forticlient:4.2.0:*:*:*:*:*:*:*
• cpe:2.3:a:fortinet:fortinet_forticlient:4.3.3.445:*:*:*:*:*:*:*
• cpe:2.3:a:fortinet:fortinet_forticlient:5.0.11:*:*:*:*:*:*:*
• cpe:2.3:a:fortinet:fortinet_forticlient:5.2.028:*:*:*:*:*:*:*
• cpe:2.3:a:fortinet:fortinet_forticlient:5.4.5:*:*:*:*:*:*:*

External links

https://securingsam.com/breaching-the-fort/

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.