Check Sendmail Configuration

# SPDX-FileCopyrightText: 2010 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("1.3.6.1.4.1.25623.1.0.96098");
  script_version("2024-01-10T05:05:17+0000");
  script_tag(name:"last_modification", value:"2024-01-10 05:05:17 +0000 (Wed, 10 Jan 2024)");
  script_tag(name:"creation_date", value:"2010-06-21 10:39:50 +0200 (Mon, 21 Jun 2010)");
  script_tag(name:"cvss_base", value:"0.0");
  script_tag(name:"cvss_base_vector", value:"AV:N/AC:L/Au:N/C:N/I:N/A:N");
  script_name("Check Sendmail Configuration");
  script_category(ACT_GATHER_INFO);
  script_copyright("Copyright (C) 2010 Greenbone AG");
  script_family("IT-Grundschutz");
  script_dependencies("compliance_tests.nasl", "gb_sendmail_smtp_detect.nasl", "check_smtp_helo.nasl");
  script_mandatory_keys("Compliance/Launch/GSHB");

  script_tag(name:"summary", value:"Checks the Sendmail Configuration.

  The Script test the SMTP Sendmail Server if the commands
  DEBUG, VRFY and EXPN are available.");

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

  exit(0);
}

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

sendmail = get_kb_item("sendmail/detected");
if (!sendmail){
  sendmaildebug = "nosendmail";
  sendmailvrfy = "nosendmail";
  sendmailexpn = "nosendmail";
} else {
  port = smtp_get_port(default:25, ignore_broken:TRUE, ignore_unscanned:TRUE);
  if(!get_port_state(port)){
    sendmaildebug = "noport";
    sendmailvrfy = "noport";
    sendmailexpn = "noport";
  } else if(smtp_get_is_marked_wrapped(port:port)){
    sendmaildebug = "nosmtp";
    sendmailvrfy = "nosmtp";
    sendmailexpn = "nosmtp";
  } else {
    soc = open_sock_tcp(port);
    if(soc) {
      b = smtp_recv_banner(socket:soc);
      s = string("DEBUG\r\n");
      send(socket:soc, data:s);
      r = recv_line(socket:soc, length:1024);
      r = tolower(r);
      if("200 debug set" >< r)
        sendmaildebug = "yes";
      else
        sendmaildebug = "no";
      smtp_close(socket:soc, check_data:r);
    } else {
      sendmaildebug = "nosoc";
    }

    soc = open_sock_tcp(port);
    if(soc) {

      b = smtp_recv_banner(socket:soc);
      send(socket:soc, data:string("EHLO ", smtp_get_helo_from_kb(port:port), "\r\n"));
      ehlotxt = smtp_recv_line(socket:soc, code:"(250|550)");

      if(ehlotxt) {

        send(socket:soc, data:string("VRFY root\r\n"));
        vrfy_txt = smtp_recv_line(socket:soc, code:"(25[0-2]|550)");
        if(vrfy_txt && !egrep(pattern:"Administrative prohibition", string:vrfy_txt) &&
                       !egrep(pattern:"Access Denied", string:vrfy_txt) &&
                       !egrep(pattern:"not available", string:vrfy_txt) &&
                       !egrep(pattern:"String does not match anything", string:vrfy_txt) &&
                       !egrep(pattern:"Cannot VRFY user", string:vrfy_txt) &&
                       !egrep(pattern:"VRFY disabled", string:vrfy_txt) &&
                       !egrep(pattern:"252 send some mail, i'll try my best", string:vrfy_txt)) {
          vtstrings = get_vt_strings();
          send(socket:soc, data:string("VRFY ", vtstrings["lowercase_rand"], '\r\n'));
          vrfy_txt2 = smtp_recv_line(socket:soc);
          if( vrfy_txt2 && ! egrep(string:vrfy_txt2, pattern:"^252")) {
            sendmailvrfy = "yes";
          } else {
            sendmailvrfy = "no";
          }
        } else {
          sendmailvrfy = "no";
        }

        send(socket:soc, data:string("EXPN root\r\n"));
        expn_txt = smtp_recv_line(socket:soc, code:"(250|550)");
        if(expn_txt && !egrep(pattern:"Administrative prohibition", string:expn_txt) &&
                       !egrep(pattern:"Access Denied", string:expn_txt) &&
                       !egrep(pattern:"lists are confidential", string:expn_txt) &&
                       !egrep(pattern:"EXPN command has been disabled", string:expn_txt) &&
                       !egrep(pattern:"not available", string:expn_txt)) {
          sendmailexpn = "yes";
        } else {
          sendmailexpn = "no";
        }
      }
      smtp_close(socket:soc, check_data:ehlotxt);
    } else {
      sendmailvrfy = "nosoc";
      sendmailexpn = "nosoc";
    }
  }
}

if(!sendmaildebug) sendmaildebug = "error";
if(!sendmailvrfy) sendmailvrfy = "error";
if(!sendmailexpn) sendmailexpn = "error";

set_kb_item(name:"GSHB/SENDMAIL/DEBUG", value:sendmaildebug);
set_kb_item(name:"GSHB/SENDMAIL/VRFX", value:sendmailvrfy);
set_kb_item(name:"GSHB/SENDMAIL/EXPN", value:sendmailexpn);
exit(0);