Microsoft Windows Remote Desktop Services RCE Vulnerability (CVE-2019-0708, BlueKeep) - Active Check

# SPDX-FileCopyrightText: 2019 Greenbone AG
# Some text descriptions might be excerpted from (a) referenced
# source(s), and are Copyright (C) by the respective right holder(s).
#
# SPDX-License-Identifier: GPL-2.0-only

if(description)
{
  script_oid("1.3.6.1.4.1.25623.1.0.108611");
  script_version("2025-03-18T05:38:50+0000");
  script_cve_id("CVE-2019-0708");
  script_tag(name:"last_modification", value:"2025-03-18 05:38:50 +0000 (Tue, 18 Mar 2025)");
  script_tag(name:"creation_date", value:"2019-07-05 11:44:28 +0000 (Fri, 05 Jul 2019)");
  script_tag(name:"cvss_base", value:"10.0");
  script_tag(name:"cvss_base_vector", value:"AV:N/AC:L/Au:N/C:C/I:C/A:C");
  script_tag(name:"severity_vector", value:"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H");
  script_tag(name:"severity_origin", value:"NVD");
  script_tag(name:"severity_date", value:"2024-07-25 14:09:24 +0000 (Thu, 25 Jul 2024)");
  script_name("Microsoft Windows Remote Desktop Services RCE Vulnerability (CVE-2019-0708, BlueKeep) - Active Check");
  script_category(ACT_ATTACK);
  script_copyright("Copyright (C) 2019 Greenbone AG");
  script_family("Windows : Microsoft Bulletins");
  script_dependencies("ms_rdp_detect.nasl");
  script_require_ports("Services/ms-wbt-server", 3389);
  script_mandatory_keys("msrdp/detected");

  script_xref(name:"URL", value:"https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2019-0708");
  script_xref(name:"URL", value:"https://support.microsoft.com/help/4499164");
  script_xref(name:"URL", value:"https://support.microsoft.com/help/4499175");
  script_xref(name:"URL", value:"https://support.microsoft.com/help/4499149");
  script_xref(name:"URL", value:"https://support.microsoft.com/help/4499180");
  script_xref(name:"URL", value:"https://support.microsoft.com/help/4500331");
  script_xref(name:"URL", value:"https://blogs.technet.microsoft.com/msrc/2019/05/14/prevent-a-worm-by-updating-remote-desktop-services-cve-2019-0708/");
  script_xref(name:"URL", value:"https://support.microsoft.com/en-us/help/4500705/customer-guidance-for-cve-2019-0708");
  script_xref(name:"URL", value:"https://docs.microsoft.com/en-us/previous-versions/windows/it-pro/windows-server-2008-R2-and-2008/cc732713(v=ws.11)");
  script_xref(name:"URL", value:"http://www.securityfocus.com/bid/108273");
  script_xref(name:"URL", value:"http://packetstormsecurity.com/files/153133/Microsoft-Windows-Remote-Desktop-BlueKeep-Denial-Of-Service.html");
  script_xref(name:"URL", value:"https://www.malwaretech.com/2019/05/analysis-of-cve-2019-0708-bluekeep.html");
  script_xref(name:"URL", value:"https://securingtomorrow.mcafee.com/other-blogs/mcafee-labs/rdp-stands-for-really-do-patch-understanding-the-wormable-rdp-vulnerability-cve-2019-0708");
  script_xref(name:"URL", value:"https://www.cisa.gov/known-exploited-vulnerabilities-catalog");
  script_xref(name:"CISA", value:"Known Exploited Vulnerability (KEV) catalog");

  script_tag(name:"summary", value:"Microsoft Windows Remote Desktop Services is prone to a remote
  code execution (RCE) vulnerability dubbed 'BlueKeep'.");

  script_tag(name:"vuldetect", value:"Sends a specially crafted request to the target systems Remote
  Desktop Service via RDP and checks the response.");

  script_tag(name:"insight", value:"A remote code execution vulnerability exists in Remote Desktop
  Services when an unauthenticated attacker connects to the target system using RDP and sends
  specially crafted requests. This vulnerability is pre-authentication and requires no user
  interaction.

  For an in-depth analysis and further technical insights and details please see the references.");

  script_tag(name:"impact", value:"Successful exploitation would allow an attacker to execute
  arbitrary code on the target system. An attacker could then install programs, view, change, or
  delete data, or create new accounts with full user rights.");

  script_tag(name:"affected", value:"- Microsoft Windows 7

  - Microsoft Windows Server 2008 R2

  - Microsoft Windows Server 2008

  - Microsoft Windows Server 2003 R2

  - Microsoft Windows Server 2003

  - Microsoft Windows Vista and Microsoft Windows XP (including Embedded)");

  script_tag(name:"solution", value:"The vendor has released updates. Please see the references for
  more information.

  As a workaround enable Network Level Authentication (NLA) on systems running supported editions of
  Windows 7, Windows Server 2008, and Windows Server 2008 R2.

  NOTE: After enabling NLA affected systems are still vulnerable to Remote Code Execution (RCE)
  exploitation if the attacker has valid credentials that can be used to successfully
  authenticate.");

  script_tag(name:"qod_type", value:"remote_vul");
  script_tag(name:"solution_type", value:"VendorFix");

  exit(0);
}

include("rdp.inc");
include("misc_func.inc");
include("port_service_func.inc");
include("dump.inc");
include("byte_func.inc");
include("bin.inc");

# nb: Available since r25570 of libs 9.0
if( ! defined_func( "rsa_public_encrypt" ) )
  exit( 0 );

port = service_get_port( default:3389, proto:"ms-wbt-server" );

if( get_kb_item( "rdp/" + port + "/isxrdp" ) )
  exit( 0 );

if( ! soc = open_sock_tcp( port, transport:ENCAPS_IP ) ) # nb: Currently don't get a response back after sending the rdp_create_pdu_negotiation_request() request if SSL/TLS is used
  exit( 0 );

req = rdp_create_pdu_negotiation_request( use_cookie:TRUE );
res = rdp_send_recv( socket:soc, data:req, debug:FALSE, debug_req_name:"rdp_create_pdu_negotiation_request()" );
len = strlen( res );

# nb: Length depends on if a mstshash Cookie was passed.
# Without a cookie length is 11
# With a cookie the length might be 11 or 19
# see https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-rdpbcgr/13757f8f-66db-4273-9d2c-385c33b1e483
if( ! res || ( len != 11 && len != 19 ) || hexstr( res ) !~ "^030000" ) {
  close( soc );
  exit( 0 );
}

req = rdp_create_pdu_connect_initial_request();
res = rdp_send_recv( socket:soc, data:req, debug:FALSE, debug_req_name:"rdp_create_pdu_connect_initial_request()" );
if( ! res ) {
  close( soc );
  exit( 0 );
}

srv_data = rdp_parse_serverdata( data:res, debug:FALSE );
if( ! srv_data ) {
  close( soc );
  exit( 0 );
}

req = rdp_create_pdu_erect_domain_request();
rdp_send( socket:soc, data:req, debug:FALSE, debug_req_name:"rdp_create_pdu_erect_domain_request()" );

req = rdp_create_pdu_attach_user_request();
res = rdp_send_recv( socket:soc, data:req, debug:FALSE, debug_req_name:"rdp_create_pdu_attach_user_request()" );
if( ! res || strlen( res ) < 11 ) {
  close( soc );
  exit( 0 );
}

user1 = substr(res, 9, 11);

foreach id( make_list( 1009, 1003, 1004, 1005, 1006, 1007, 1008 ) ) {
  req = rdp_create_pdu_channel_request( user1:user1, channel_id:id, debug:FALSE );
  rdp_send_recv( socket:soc, data:req, debug:FALSE, debug_req_name:"rdp_create_pdu_channel_request()" );
}

client_rand = rdp_create_client_random();

req = rdp_create_pdu_security_exchange( client_rand:client_rand,
                                        public_exponent:srv_data["public_exponent"],
                                        modulus:srv_data["modulus"],
                                        bitlen:srv_data["bitlen"] );
rdp_send( socket:soc, data:req, debug:FALSE, debug_req_name:"rdp_create_pdu_security_exchange()" );

client_info_pkt = rdp_create_pdu_client_info_request();

rc4_keys = rdp_calculate_rc4_keys( client_rand:client_rand, server_rand:srv_data["server_random"], debug:FALSE );

client_confirm_active = rdp_create_pdu_client_confirm_active_request();

sync = rdp_create_pdu_client_synchronize_request( target_user:1009 );

coop = rdp_build_pdu_client_control_cooperate();

client_req_control = rdp_create_pdu_client_control_request();

event_sync = rdp_create_pdu_client_input_event_sychronize_request();

font_list = rdp_create_pdu_client_font_list_request();

# 0x03 = CHANNEL_FLAG_FIRST | CHANNEL_FLAG_LAST
x86_payload = rdp_build_virtual_channel_pdu_request( flags:0x03, data:raw_string( 0x00, 0x00, 0x00, 0x00, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 ) );
x64_payload = rdp_build_virtual_channel_pdu_request( flags:0x03, data:raw_string( 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 ) );

# the whole static data which has to be encrypted
full_data = client_info_pkt + client_confirm_active + sync + coop + client_req_control + event_sync + font_list;
for( i = 0; i <= 5; i++ ) {
  full_data += x86_payload;
  full_data += x64_payload;
}

enc_data = rc4_encrypt( key:rc4_keys["initial_client_encryptkey_128"], data:full_data );

# Dissect the encrypted data again
# TODO: NASL rc4_encrypt currently can't encrypt the data for our purposes so
# the data needs to be dissected here (see comment in rdp_build_pkt() as well).
start = 0;
end = strlen( client_info_pkt ) - 1;
enc_client_info_pkt = substr( enc_data, start, end );
enc_client_info_pkt = rdp_build_pkt( data:client_info_pkt, client_info:TRUE, rdp_sec:TRUE, enc_data:enc_client_info_pkt, hmackey:rc4_keys["mac_key"] );

start = end + 1;
end = start + strlen( client_confirm_active ) - 1;
enc_client_confirm_active = substr( enc_data, start, end );
enc_client_confirm_active = rdp_build_pkt( data:client_confirm_active, rdp_sec:TRUE, enc_data:enc_client_confirm_active, hmackey:rc4_keys["mac_key"] );

start = end + 1;
end = start + strlen( sync ) - 1;
enc_sync = substr( enc_data, start, end );
enc_sync = rdp_build_pkt( data:sync, rdp_sec:TRUE, enc_data:enc_sync, hmackey:rc4_keys["mac_key"] );

start = end + 1;
end = start + strlen( coop ) - 1;
enc_coop = substr( enc_data, start, end );
enc_coop = rdp_build_pkt( data:coop, rdp_sec:TRUE, enc_data:enc_coop, hmackey:rc4_keys["mac_key"] );

start = end + 1;
end = start + strlen( client_req_control ) - 1;
enc_client_req_control = substr( enc_data, start, end );
enc_client_req_control = rdp_build_pkt( data:client_req_control, rdp_sec:TRUE, enc_data:enc_client_req_control, hmackey:rc4_keys["mac_key"] );

start = end + 1;
end = start + strlen( event_sync ) - 1;
enc_event_sync = substr( enc_data, start, end );
enc_event_sync = rdp_build_pkt( data:event_sync, rdp_sec:TRUE, enc_data:enc_event_sync, hmackey:rc4_keys["mac_key"] );

start = end + 1;
end = start + strlen( font_list ) - 1;
enc_font_list = substr( enc_data, start, end );
enc_font_list = rdp_build_pkt( data:font_list, rdp_sec:TRUE, enc_data:enc_font_list, hmackey:rc4_keys["mac_key"] );

enc_x86_payload_list = make_list();
enc_x64_payload_list = make_list();

for (i=0; i<=5; i++) {
  start = end + 1;
  end = start + strlen( x86_payload ) - 1;
  enc_x86_payload = substr( enc_data, start, end );
  # 0xed03 = Channel 1005
  enc_x86_payload = rdp_build_pkt( data:x86_payload, rdp_sec:TRUE, channel_id:raw_string( 0x03, 0xed ), enc_data:enc_x86_payload, hmackey:rc4_keys["mac_key"] );
  enc_x86_payload_list[i] = enc_x86_payload;

  start = end + 1;
  end = start + strlen( x64_payload ) - 1;
  enc_x64_payload = substr( enc_data, start, end );
  # 0xed03 = Channel 1005
  enc_x64_payload = rdp_build_pkt( data:x64_payload, rdp_sec:TRUE, channel_id:raw_string( 0x03, 0xed ), enc_data:enc_x64_payload, hmackey:rc4_keys["mac_key"] );
  enc_x64_payload_list[i] = enc_x64_payload;
}

res = rdp_send_recv( socket:soc, data:enc_client_info_pkt, debug:FALSE, debug_req_name:"rdp_create_pdu_client_info_request() / License packet" );
# nb: Windows XP sometimes sends a very large license packet. This is likely
# some form of license error. When it does this it doesn't send a Server
# Demand packet. If we wait on one we will time out here and error. We
# can still successfully check for vulnerability anyway.
if( ! res || strlen( res ) <= 34 )
  rdp_recv( socket:soc, debug:FALSE, debug_req_name:"Server Demand packet" );

# nb: Keep the code here as is and don't raise the received length or e.g. use rdp_send_recv(). For some unknown reason trying
# to change such things will cause a false negative against Windows XP systems.
rdp_send( socket:soc, data:enc_client_confirm_active, debug:FALSE, debug_req_name:"rdp_create_pdu_client_confirm_active_request()" );

rdp_send( socket:soc, data:enc_sync + enc_coop, debug:FALSE, debug_req_name:"rdp_create_pdu_client_synchronize_request() and rdp_build_pdu_client_control_cooperate()" );

rdp_send( socket:soc, data:enc_client_req_control, debug:FALSE, debug_req_name:"rdp_create_pdu_client_control_request()" );

rdp_send( socket:soc, data:enc_event_sync, debug:FALSE, debug_req_name:"rdp_create_pdu_client_input_event_sychronize_request()" );

rdp_send( socket:soc, data:enc_font_list, debug:FALSE, debug_req_name:"rdp_create_pdu_client_font_list_request()" );

# nb: Receive all data / clear the socket before sending the payloads below.
for( i = 0; i <= 5; i++ ) {
  _res = rdp_recv( socket:soc );
  if( ! _res )
    recv( socket:soc, length:1024, min:1 );
}

report = "By sending a crafted request the RDP service answered with a 'MCS Disconnect Provider Ultimatum PDU - 2.2.2.3' response which indicates that a RCE attack can be executed.";

for( i = 0; i <= 5; i++ ) {

  rdp_send( socket:soc, data:enc_x86_payload_list[i], debug:FALSE, debug_req_name:"x86 payload of rdp_build_virtual_channel_pdu_request()" );
  rdp_send( socket:soc, data:enc_x64_payload_list[i], debug:FALSE, debug_req_name:"x64 payload of rdp_build_virtual_channel_pdu_request()" );

  # nb: Don't use rdp_recv() as it might not receive all data due to unexpected RDP packages
  # received where the length calculation from the header doesn't work as expected.
  res = recv( socket:soc, length:2048, min:1 );
  if( res && hexstr( res ) =~ "^0300000902f0802180$" ) {
    close( soc );
    security_message( port:port, data:report );
    exit( 0 );
  }

  for( j = 0; j<= 3; j++ ) {
    res = recv( socket:soc, length:2048, min:1 );
    if( res && hexstr( res ) =~ "^0300000902f0802180$" ) {
      close( soc );
      security_message( port:port, data:report );
      exit( 0 );
    }
  }
}

close( soc );
exit( 0 );