Generic SMTP overflows

# SPDX-FileCopyrightText: 2003 Michel Arboi
# 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("1.3.6.1.4.1.25623.1.0.11772");
  script_version("2023-07-21T05:05:22+0000");
  script_tag(name:"last_modification", value:"2023-07-21 05:05:22 +0000 (Fri, 21 Jul 2023)");
  script_tag(name:"creation_date", value:"2005-11-03 14:08:04 +0100 (Thu, 03 Nov 2005)");
  script_tag(name:"cvss_base", value:"7.5");
  script_tag(name:"cvss_base_vector", value:"AV:N/AC:L/Au:N/C:P/I:P/A:P");
  script_name("Generic SMTP overflows");
  script_category(ACT_DESTRUCTIVE_ATTACK);
  script_copyright("Copyright (C) 2003 Michel Arboi");
  script_family("SMTP problems");
  script_dependencies("smtpserver_detect.nasl");
  script_require_ports("Services/smtp", 25, 465, 587);
  script_mandatory_keys("smtp/banner/available");

  script_tag(name:"solution", value:"Upgrade your MTA or change it.");

  script_tag(name:"summary", value:"The remote SMTP server crashes when it is send a command
  with a too long argument.");

  script_tag(name:"impact", value:"An attacker might use this flaw to kill this service or worse, execute arbitrary code on your server.");

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

  exit(0);
}

include("smtp_func.inc");
include("misc_func.inc");
include("port_service_func.inc");

port = smtp_get_port(default:25);
if(smtp_get_is_marked_wrapped(port:port))
  exit(0);

host = get_host_name();

soc = open_sock_tcp(port);
if(!soc)
  exit(0);

banner = smtp_recv_banner(socket:soc);
if(!banner) {
  smtp_close(socket:soc, check_data:banner);
  exit(0);
}

cmds = make_list("HELO", "EHLO", "MAIL FROM:",
                 "RCPT TO:", "ETRN");
args = make_list("test.example.org", "test.example.org",
                 strcat("test@", host), strcat("test@[", get_host_ip(), "]"),
                 "test.example.org");
n = max_index(cmds);

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

  send(socket:soc, data:string(cmds[i], " ", str_replace(string:args[i], find:"test", replace: crap(4095)), "\r\n"));
  repeat
  {
    data = recv_line(socket:soc, length:32768);
  }
  until (data !~ '^[0-9]{3}[ -]');

  # A Postfix bug: it answers with two codes on an overflow
  repeat
  {
    data2 = recv_line(socket:soc, length:32768, timeout:1);
  }
  until (data2 !~ '^[0-9]{3}[ -]');

  if(!data) {

    close(soc);
    soc = open_sock_tcp(port);
    if(!soc) {
      security_message(port);
      exit(0);
    }
    for (j = 0; j <= i; j ++) {
      send(socket:soc, data:string(cmds[i], " ", args[i], "r\n"));
      data = recv_line(socket:soc, length:32768);
    }
  }
}

smtp_close(socket:soc, check_data:data);
exit(99);