Fortinet FortiOS < 4.3.13 SSL-VPN TLS MAC Spoofing
Medium Nessus Plugin ID 85806
SynopsisThe remote host is affected by a man-in-the-middle spoofing vulnerability.
DescriptionThe remote host is running a version of FortiOS prior to 4.3.13. It is, therefore, affected by a man-in-the-middle spoofing vulnerability due to a flaw in the SSL-VPN feature. The SSL-VPN feature only validates the first byte of the TLS MAC in finished messages. A remote, man-in-the-middle attacker can exploit this, via a crafted MAC field, to spoof encrypted content, potentially resulting in the disclosure of sensitive information.
SolutionUpgrade to Fortinet FortiOS 4.3.14 or later.
Note that version 4.3.13 contained the earliest fix; however, that version contained an unrelated error and was removed from distribution.