Explicit Proxy - SOCKS

We've a FortiGate 1000D with a VDOM doing an Explicit Proxy role, this VDOM has SOCKS enabled into web-proxy settings and for our surprise we realized that if a client use only SOCKS (Ex. Firefox) it's not reachable for any of the security policy that we have for HTTP/HTTPS . It's there any way that SOCKS can be reachable for these Security Policies? 

sh full-configuration web-proxy explicit  

  set status enable   

  set ftp-over-http enable   

  set socks enable   

  set http-incoming-port 8080    

  set https-incoming-port 0   

  set ftp-incoming-port 0   

  set socks-incoming-port 0   

  set incoming-ip 0.0.0.0   

  set ipv6-status disable   

  set strict-guest disable    

  set unknown-http-version best-effort   

  set realm "proxy"   

  set sec-default-action deny   

  set https-replacement-message enable   

  set message-upon-server-error enable   

  set pac-file-server-status enable   

  set pac-file-server-port 0   

  set pac-file-name "proxy.pac"   

  set ssl-algorithm low