FTP Server Traversal Arbitrary File Access - Nessus

Medium Plugin ID: 11112

This page contains detailed information about the FTP Server Traversal Arbitrary File Access Nessus plugin including available exploits and PoCs found on GitHub, in Metasploit or Exploit-DB for verifying of this vulnerability.

Table Of Contents

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Plugin Overview
Vulnerability Information

Synopsis
Description
Solution

Public Exploits
Risk Information
Plugin Source
How to Run
References
Version

Plugin Overview

ID: 11112
Name: FTP Server Traversal Arbitrary File Access
Filename: ftp_traversal.nasl
Vulnerability Published: 2001-04-13
This Plugin Published: 2002-08-27
Last Modification Time: 2019-02-26
Plugin Version: 1.60
Plugin Type: remote
Plugin Family: FTP
Dependencies: ftp_anonymous.nasl, ftpserver_detect_type_nd_version.nasl, os_fingerprint.nasl
Required KB Items [?]: ftp/login
Excluded KB Items: ftp/msftpd, ftp/ncftpd

Vulnerability Information

Severity: Medium
Vulnerability Published: 2001-04-13
Patch Published: N/A
CVE [?]: CVE-2001-0582, CVE-2001-0680, CVE-2001-1335, CVE-2004-1679
CPE [?]: N/A

Synopsis

The remote FTP server is susceptible to a directory traversal attack.

Description

The remote FTP server allows users to browse the entire remote disk by issuing commands with traversal style characters. An attacker could exploit this flaw to gain access to arbitrary files.

Solution

Contact your vendor for the latest version of the FTP software.

Public Exploits

Target Network Port(s): 21
Target Asset(s): Services/ftp
Exploit Available: True (GitHub)
Exploit Ease: Exploits are available

Here's the list of publicly known exploits and PoCs for verifying the FTP Server Traversal Arbitrary File Access vulnerability:

GitHub: https://github.com/alt3kx/CVE-2001-0680
[CVE-2001-0680: Directory traversal vulnerability in ftpd in QPC QVT/Net 4.0 and AVT/Term 5.0]
GitHub: https://github.com/alt3kx/alt3kx.github.io
[CVE-2001-0680]

Before running any exploit against any system, make sure you are authorized by the owner of the target system(s) to perform such activity. In any other case, this would be considered as an illegal activity.

WARNING: Beware of using unverified exploits from sources such as GitHub or Exploit-DB. These exploits and PoCs could contain malware. For more information, see how to use exploits safely.

Risk Information

CVSS Score Source [?]: CVE-2001-0582
CVSS V2 Vector: AV:N/AC:L/Au:N/C:N/I:P/A:N/E:POC/RL:OF/RC:C

CVSS Base Score:	5.0 (Medium)
Impact Subscore:	2.9
Exploitability Subscore:	10.0
CVSS Temporal Score:	3.9 (Low)
CVSS Environmental Score:	NA (None)
Modified Impact Subscore:	NA
Overall CVSS Score:	3.9 (Low)

CVSS V3 Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

CVSS Base Score:	5.3 (Medium)
Impact Subscore:	1.4
Exploitability Subscore:	3.9
CVSS Temporal Score:	NA (None)
CVSS Environmental Score:	NA (None)
Modified Impact Subscore:	NA
Overall CVSS Score:	5.3 (Medium)

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Plugin Source

#TRUSTED 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
###
# (C) Tenable Network Security, Inc.
#

include("compat.inc");

if (description)
{
  script_id(11112);
  script_version("1.60");
  script_cvs_date("Date: 2019/02/26  4:50:08");

  script_cve_id("CVE-2001-0582", "CVE-2001-0680", "CVE-2001-1335", "CVE-2004-1679");
  script_bugtraq_id(11159, 2618, 2786, 38756, 44759, 5168);

  script_name(english:"FTP Server Traversal Arbitrary File Access");
  script_summary(english:"Attempts to get the listing of the remote root dir.");

  script_set_attribute(attribute:"synopsis", value:
"The remote FTP server is susceptible to a directory traversal attack.");
  script_set_attribute(attribute:"description", value:
"The remote FTP server allows users to browse the entire remote disk by
issuing commands with traversal style characters. An attacker could
exploit this flaw to gain access to arbitrary files.");
  # https://web.archive.org/web/20020227075045/http://archives.neohapsis.com/archives/bugtraq/2001-04/0231.html
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?83ccf5c4");
  script_set_attribute(attribute:"see_also", value:"https://seclists.org/bugtraq/2001/May/248");
  script_set_attribute(attribute:"see_also", value:"https://seclists.org/bugtraq/2004/Sep/119");
  script_set_attribute(attribute:"see_also", value:"https://seclists.org/bugtraq/2001/May/35");
  script_set_attribute(attribute:"solution", value:"Contact your vendor for the latest version of the FTP software.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:N/I:P/A:N");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N");
  script_set_cvss_temporal_vector("CVSS2#E:POC/RL:OF/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2001-0582");
  script_set_attribute(attribute:"exploitability_ease", value:"Exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"true");

  script_set_attribute(attribute:"vuln_publication_date", value:"2001/04/13");
  script_set_attribute(attribute:"plugin_publication_date", value:"2002/08/27");

  script_set_attribute(attribute:"plugin_type", value:"remote");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"FTP");

  script_copyright(english:"This script is Copyright (C) 2002-2019 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("ftpserver_detect_type_nd_version.nasl", "ftp_anonymous.nasl", "os_fingerprint.nasl");
  script_exclude_keys("ftp/ncftpd", "ftp/msftpd");
  script_require_keys("ftp/login");
  script_require_ports("Services/ftp", 21);

  exit(0);
}

#
# The script code starts here
#

include("audit.inc");
include("ftp_func.inc");
include("global_settings.inc");

port = get_ftp_port(default: 21);

function dir(loc, soc)
{
  local_var ls, p, r, result, soc2;

  p = ftp_pasv(socket:soc);
  if(!p) exit(1, "PASV command failed on port "+port+".");
  soc2 = open_sock_tcp(p, transport:get_port_transport(port));
  if(!soc2)return NULL;

  #display("Ok\n");
  ls = 'LIST ' + string(loc) + '\r\n';
  send(socket:soc, data:ls);
  r = recv_line(socket:soc, length:4096);
  if(preg(pattern:"^150 ", string:r))
  {
    result = ftp_recv_listing(socket:soc2);
    close(soc2);
    r = ftp_recv_line(socket:soc);
    return(result);
  }
  close(soc2);
  return NULL;
}

# Compares two directory listings (assumes the first provided is legit).
# Returns TRUE if the lists are both valid and differ, FALSE otherwise
function list_diff()
{
  local_var a, b;
  a = _FCT_ANON_ARGS[0];
  b = _FCT_ANON_ARGS[1];

  return
    strlen(b) &&
    preg(pattern:"[a-zA-Z0-9]", string:b) &&
    ! match(string: b, pattern: "*permission denied*", icase: TRUE) &&
    ! match(string: b, pattern: "*no such file or directory*", icase: TRUE) &&
    ! match(string: b, pattern: "*not found*", icase: TRUE) &&
    ! match(string: b, pattern: "*total 0*", icase: TRUE) &&
    a != b;
}

user = get_kb_item('ftp/login');
pass = get_kb_item('ftp/password');

if (isnull(user))
{
  if (supplied_logins_only) audit(AUDIT_SUPPLIED_LOGINS_ONLY);
  user = 'anonymous';
}
if (isnull(pass))
{
  if (supplied_logins_only) audit(AUDIT_SUPPLIED_LOGINS_ONLY);
  pass = '[email protected]';
}

soc = ftp_open_and_authenticate( user:user, pass:pass, port:port );
if(!soc)
  exit(1, "Cannot authenticate on port "+port+".");

# Try to access the root directory using different paths, trying a
# couple times for each path.
l2 = NULL; l1 = NULL;
foreach loc (make_list("/", "/*"))
{
  for (i = 0; i < 2 && !l2; i++)
    l2 = dir(loc:loc, soc:soc);
  if (!isnull(l2)) break;
}

if (isnull(l2))
{
  ftp_close(socket:soc);
  exit(1, "No answer for DIR / on port "+port+".");
}

# Try to access the root directory again, using the same path that
# worked last time.
for (i = 0; i < 2 && !l1; i++)
  l1 = dir(loc:loc, soc:soc);

# Ensure that the FTP server is consistently giving us the same view
# of the root directory.
if (l1 != l2)
{
  ftp_close(socket:soc);
  exit(1, "Varying output for DIR / on port "+port+".");
}

# If we know the OS the remote host is using, we can limit our
# requests. Only do this when not paranoid.
dirs = NULL;
if (report_paranoia < 2)
{
  os = get_kb_item("Host/OS");
  if (!isnull(os))
  {
    if ("Windows" >< os)
      dirs = make_list("/windows");
    else
      dirs = make_list("/etc");
  }
}

# If we couldn't narrow down what to check, try everything.
if (isnull(dirs))
  dirs = make_list("/etc", "/windows");

# These are the generic traversal strings. The booleans indicate
# whether the traversal string is likely to get us back to the root
# directory.
generic = make_array(
  "../../../../../../../", TRUE,
  "..\..\..\..\..\..\..\", TRUE,
  "..%5c..%5c..%5c..%5c..%5c..%5c..%5c", TRUE,
  "\..\..\..\..\..\", TRUE,
  "...", FALSE,
  "/...", FALSE,
  "/......", FALSE,
  "\...", FALSE,
  "...\", FALSE,
  "..../", FALSE,
  "\", FALSE,
  "/", FALSE,
  "..:/..:/..:/..:/..:/..:/..:/..:/", TRUE,
  "..:\..:\..:\..:\..:\..:\..:\..:\", TRUE
);

# Transform the generic traversal strings to include directory names
# for the traversal strings that might get us to the host's root
# directory.
patterns = make_list();
foreach pattern (keys(generic))
{
  patterns = make_list(patterns, pattern);

  if (!generic[pattern]) continue;

  foreach dir (dirs)
  {
    patterns = make_list(patterns, pattern + dir);
  }
}

vuln = FALSE;

foreach pat (patterns)
{
  # First try using the dir traversal directly in the LIST command
  l2 = dir(loc: pat, soc: soc);
  vuln = list_diff(l1, l2);

  # If that didn't work, try passing the directory traversal string to
  # CWD first, and then trying a LIST
  if (!vuln)
  {
    r = ftp_send_cmd(socket:soc, cmd:'CWD '+pat);

    if (preg(pattern:"^250 ", string:r))
    {
      l2 = dir(loc:'', soc:soc);
      vuln = list_diff(l1, l2);
      cmd = 'CWD';
    }
  }
  else cmd = 'LIST';

  if (vuln && report_paranoia < 2)
  {
    # Recheck the initial directory to make sure the change in the
    # directory listing found with the attack isn't just a
    # coincidental change in the initial directory itself.
    l3 = dir(loc:loc, soc:soc);
    if (list_diff(l1, l3) && !list_diff(l3, l2)) vuln = FALSE;
  }

  if (vuln)
  {
     #display(l1, "\n****\n"); display(l2, "\n");
     report =
       '\nThe command we found to escape the chrooted environment is : ' +
       string(cmd) + ' ' + pat +
       '\n' +
       '\nThis directory contains :\n\n' + string(l2);
     security_warning(port:port, extra:report);
     ftp_close(socket: soc);
     exit(0);
  }
}
ftp_close(socket: soc);
audit(AUDIT_LISTEN_NOT_VULN, 'FTP Server', port);

The latest version of this script can be found in these locations depending on your platform:

Linux / Unix:
/opt/nessus/lib/nessus/plugins/ftp_traversal.nasl
Windows:
C:\ProgramData\Tenable\Nessus\nessus\plugins\ftp_traversal.nasl
Mac OS X:
/Library/Nessus/run/lib/nessus/plugins/ftp_traversal.nasl

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How to Run

Here is how to run the FTP Server Traversal Arbitrary File Access as a standalone plugin via the Nessus web user interface (https://localhost:8834/):

Click to start a New Scan.
Select Advanced Scan.
Navigate to the Plugins tab.
On the top right corner click to Disable All plugins.
On the left side table select FTP plugin family.
On the right side table select FTP Server Traversal Arbitrary File Access plugin ID 11112.
Specify the target on the Settings tab and click to Save the scan.
Run the scan.

Here are a few examples of how to run the plugin in the command line. Note that the examples below demonstrate the usage on the Linux / Unix platform.

Basic usage:

/opt/nessus/bin/nasl ftp_traversal.nasl -t <IP/HOST>

Run the plugin with audit trail message on the console:

/opt/nessus/bin/nasl -a ftp_traversal.nasl -t <IP/HOST>

Run the plugin with trace script execution written to the console (useful for debugging):

/opt/nessus/bin/nasl -T - ftp_traversal.nasl -t <IP/HOST>

Run the plugin with using a state file for the target and updating it (useful for running multiple plugins on the target):

/opt/nessus/bin/nasl -K /tmp/state ftp_traversal.nasl -t <IP/HOST>

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References

BID | SecurityFocus Bugtraq ID:

2618, 2786, 5168, 11159, 38756, 44759

See also:

Similar and related Nessus plugins:

11755 - CesarFTP Multiple Vulnerabilities (OF, File Access, more)
50811 - FTP Server Traversal Arbitrary File Access (RETR)
10084 - Multiple FTP Server Command Handling Overflow
12080 - Serv-U MDTM Command Overflow
12037 - Serv-U SITE CHMOD Command Multiple Vulnerabilities
53847 - FTP Service AUTH TLS Plaintext Command Injection

Version

This page has been produced using Nessus Professional 10.1.2 (#68) LINUX, Plugin set 202205072148.
Plugin file ftp_traversal.nasl version 1.60. For more plugins, visit the Nessus Plugin Library.

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FTP Server Traversal Arbitrary File Access - Nessus

Plugin Overview

Vulnerability Information

Synopsis

Description

Solution

Public Exploits

Risk Information

Plugin Source

How to Run

References

Version

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