Cisco IOS FTP Server Authentication Bypass Vulnerability

# SPDX-FileCopyrightText: 2008 Ferdy Riphagen
# 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("1.3.6.1.4.1.25623.1.0.9999996");
  script_version("2023-08-01T13:29:10+0000");
  script_tag(name:"last_modification", value:"2023-08-01 13:29:10 +0000 (Tue, 01 Aug 2023)");
  script_tag(name:"creation_date", value:"2008-08-22 16:09:14 +0200 (Fri, 22 Aug 2008)");
  script_tag(name:"cvss_base", value:"9.3");
  script_tag(name:"cvss_base_vector", value:"AV:N/AC:M/Au:N/C:C/I:C/A:C");
  script_cve_id("CVE-2007-2586");
  script_name("Cisco IOS FTP Server Authentication Bypass Vulnerability");
  script_category(ACT_GATHER_INFO);
  script_tag(name:"qod_type", value:"remote_active");
  script_family("FTP");
  script_copyright("Copyright (C) 2008 Ferdy Riphagen");
  script_dependencies("ftpserver_detect_type_nd_version.nasl");
  script_require_ports("Services/ftp", 21);
  script_mandatory_keys("ftp/cisco/ios_ftp/detected");

  script_tag(name:"summary", value:"The Cisco IOS FTP server is enabled on the remote system
  which does not properly verify authentication, allowing for anonymous access to the file system.");

  script_tag(name:"impact", value:"An attacker could use the ftp server to view/download confidential
  configuration files, or upload replacements which will be used at startup.");

  script_xref(name:"URL", value:"http://www.cisco.com/en/US/products/products_security_advisory09186a00808399d0.shtml");
  script_xref(name:"URL", value:"http://www.securityfocus.com/bid/23885");

  script_tag(name:"solution_type", value:"WillNotFix");

  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.");

  exit(0);
}

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

function start_passive(port, soc) {

  pasv = ftp_pasv(socket:soc);
  if (!pasv) return NULL;
  soc2 = open_sock_tcp(pasv, transport:get_port_transport(port));
  if (!soc2) return NULL;
  return;
}

port = ftp_get_port( default:21 );
banner = ftp_get_banner(port:port);
if(!banner || "IOS-FTP server" >!< banner)
  exit(0);

# nb: Try to get some directory listing.
# On the other hand ftp_anonymous.nasl is doing this too :-)
soc = open_sock_tcp(port);
if (soc &&
   (ftp_authenticate(socket:soc, user:"blah", pass:"blah"))) {
  if (start_passive(port:port, soc:soc)) {
    send(socket:soc, data:'LIST\r\n');
    recv_listing = ftp_recv_listing(socket:soc2);
    ftp_close(socket:soc2);
  }
}
if (soc) ftp_close(socket:soc);

# That's what it's all about..
if (strlen(recv_listing)) {
  soc = open_sock_tcp(port);
  if (soc &&
     (ftp_authenticate(socket:soc, user:"blah", pass:"blah"))) {
    send(socket:soc, data:'CWD nvram:\r\n');
    recv = ftp_recv_line(socket:soc, retry:1);
    if ("250" >< recv &&
       (start_passive(port:port, soc:soc))) {
      send(socket:soc, data:'RETR startup-config\r\n');
      recv_config = ftp_recv_data(socket:soc2, line:500);
      ftp_close(socket:soc2);
    }
  }
}
if (soc) ftp_close(socket:soc);

if (strlen(recv_config)) {
  report = string("Partial startup-config file:\r\n", recv_config);
  security_message(port:port, data:report);
  exit(0);
}
else if (strlen(recv_listing)) {
  security_message(port:port);
  exit(0);
}