Fortinet FortiSIEM 5.0 / 5.2.1 Improper Certification Validation

A FortiSIEM collector connects to a Supervisor/Worker over HTTPS TLS (443/TCP) to register itself as well as relaying event data such as syslog, netflow, SNMP, etc. When the Collector (the client) connects to the Supervisor/Worker (the server), the client does not validate the server-provided certificate against its root-CA store. Since the client does no server certificate validation, this means any certificate presented to the client will be considered valid and the connection will succeed. If an attacker spoofs a Worker/Supervisor using an ARP or DNS poisoning attack (or any other MITM attack), the Collector will blindly connect to the attacker's HTTPS TLS server. It will disclose the authentication password used along with any data being relayed. Versions 5.0 and 5.2.1 have been tested and are affected.