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New Contributor III

ROBOT vulnerability mitigation?

I have a 100D running 5.4.8 with an HTTPS type virtual server VIP, and is marking the site in question as vulnerable to ROBOT (Return of Bleichenbacher's Oracle Threat) attack. The VIP settings are currently set as follows:


        set ssl-mode full         set ssl-dh-bits 2048         set ssl-algorithm high         set ssl-server-algorithm client         set ssl-pfs allow         set ssl-min-version tls-1.0         set ssl-max-version tls-1.2         set ssl-server-min-version client         set ssl-server-max-version client         set ssl-send-empty-frags enable         set ssl-client-fallback enable         set ssl-client-renegotiation secure         set ssl-client-session-state-type both         set ssl-client-session-state-timeout 30         set ssl-client-session-state-max 1000         set ssl-server-session-state-type both         set ssl-server-session-state-timeout 60         set ssl-server-session-state-max 100

Fortinet's official advisory is that FortiOS is not affected ( ) - is this a false positive on the part of SSLLabs, or is it true, and if yes, what can be done to mitigate it?

Valued Contributor

did you open a ticket with support? in principle it seems RSA ciphers are vulnerable and those are offered with a normal virtual server.


mitigation is possible to selecting non RSA ciphers


config firewall vip     edit "vsrv-name"         …         …         set ssl-algorithm custom         config ssl-cipher-suites             edit 1                 set cipher TLS-ECDHE-RSA-WITH-AES-128-CBC-SHA             next             edit 2                 set cipher TLS-ECDHE-RSA-WITH-AES-128-CBC-SHA256             next             edit 3                 set cipher TLS-ECDHE-RSA-WITH-AES-128-GCM-SHA256             next             edit 4                 set cipher TLS-ECDHE-RSA-WITH-AES-256-CBC-SHA             next             edit 5                 set cipher TLS-ECDHE-RSA-WITH-AES-256-CBC-SHA384             next             edit 6                 set cipher TLS-ECDHE-RSA-WITH-AES-256-GCM-SHA384             next             edit 7                 set cipher TLS-ECDHE-ECDSA-WITH-AES-128-CBC-SHA             next             edit 8                 set cipher TLS-ECDHE-ECDSA-WITH-AES-128-CBC-SHA256             next             edit 9                 set cipher TLS-ECDHE-ECDSA-WITH-AES-128-GCM-SHA256             next             edit 10                 set cipher TLS-ECDHE-ECDSA-WITH-AES-256-CBC-SHA384             next             edit 11                 set cipher TLS-ECDHE-ECDSA-WITH-AES-256-GCM-SHA384             next             edit 12                 set cipher TLS-DHE-RSA-WITH-AES-128-CBC-SHA             next             edit 13                 set cipher TLS-DHE-RSA-WITH-AES-256-CBC-SHA             next             edit 14                 set cipher TLS-DHE-RSA-WITH-AES-128-CBC-SHA256             next             edit 15                 set cipher TLS-DHE-RSA-WITH-AES-128-GCM-SHA256             next             edit 16                 set cipher TLS-DHE-RSA-WITH-AES-256-CBC-SHA256             next             edit 17                 set cipher TLS-DHE-RSA-WITH-AES-256-GCM-SHA384             next         end         ssl-client-renegotiation secure     next end

gets you a A on ssl labs

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