Difference between revisions of "Resource Injection"

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==Abstract==
+
==Description==
  
Allowing user input to control resource identifiers may enable an attacker to access or modify otherwise protected system resources.
+
This attack consists in changing resources identifiers used by application in order to perform malicious task. When an application permits a user input to define a resource, like file name or port number, this data can be manipulated to execute or access different resources.
 +
<br>
 +
In order to be properly executed, the attacker must have the possibility to specify a resource identifier thru application form and the application must permit its execution.
  
==Description==
+
The resource type affected by user input indicates the content type that may be exposed. For example, an application that permits input of special characters like period, slash, and backslash are risky when used in methods that interact with the file system.
  
A resource injection issue occurs when the following two conditions are met:
+
The resource injection attack focus on accessing other resources than local filesystem, whose is done thru a different attack technique known as [[Path Manipulation]] attack.<br>
  
# An attacker can specify the identifier used to access a system resource. For example, an attacker might be able to specify part of the name of a file to be opened or a port number to be used.
 
# By specifying the resource, the attacker gains a capability that would not otherwise be permitted. For example, the program may give the attacker the ability to overwrite the specified file or run with a configuration controlled by the attacker.
 
  
 
==Examples ==
 
==Examples ==
  
 
===Example 1===
 
===Example 1===
 +
The following examples represent an application which gets a port number from HTTP request and create a socket with this port number without any validation. A user using a proxy can modify this port and obtain a direct connection (socket) with the server.
 +
<br><br>
  
The following Java code uses input from an HTTP request to create a file name. The programmer has not considered the possibility that an attacker could provide a file name such as "../../tomcat/conf/server.xml", which causes the application to delete one of its own configuration files.
+
'''Java code:'''
 +
 
 +
String rPort = request.getParameter("remotePort");
 +
...
 +
ServerSocket srvr = new ServerSocket(rPort);
 +
Socket skt = srvr.accept();
 +
...
 +
 
 +
<br>
 +
'''.Net code:'''
 +
 
 +
int rPort = Int32.Parse(Request.get_Item("remotePort "));
 +
...
 +
IPEndPoint endpoint = new IPEndPoint(address,rPort);
 +
socket = new Socket(endpoint.AddressFamily,
 +
SocketType.Stream, ProtocolType.Tcp);
 +
socket.Connect(endpoint);
 +
...
  
<pre>
 
String rName = request.getParameter("reportName");
 
File rFile = new File("/usr/local/apfr/reports/" + rName);
 
...
 
rFile.delete();
 
</pre>
 
  
 
===Example 2===
 
===Example 2===
 +
This example is same as previous, but it gets port number from CGI requests using C++:
  
The following C++ code uses input from the command line to determine which file to open and echo back to the user. If the program runs with privileges and malicious users can create soft links to the file, they can use the program to read the first part of any file on the system.
+
char* rPort = getenv("remotePort ");
 +
...
 +
serv_addr.sin_port = htons(atoi(rPort));
 +
if (connect(sockfd,&serv_addr,sizeof(serv_addr)) < 0)
 +
error("ERROR connecting");
 +
...
 +
 
 +
 
 +
===Example 3===
 +
This example in PLSQL / TSQL gets a URL path from a CGI and downloads the file contained on it. If a user modify the path or filename it’s possible to download arbitrary files from server:
 +
...
 +
filename := SUBSTR(OWA_UTIL.get_cgi_env('PATH_INFO'), 2);
 +
WPG_DOCLOAD.download_file(filename);
 +
...
 +
 
 +
 
 +
==References==
 +
http://samate.nist.gov/SRD/view_testcase.php?login=Guest&tID=1734 <br>
 +
http://cwe.mitre.org/data/definitions/99.html <br>
 +
http://capec.mitre.org/data/index.html#Definition <br>
 +
http://www.fortifysoftware.com/vulncat/ <br>
 +
G. Hoglund and G. McGraw. Exploiting Software. Addison-Wesley, 2004.
  
<pre>
 
ifstream ifs(argv[0]);
 
string s;
 
ifs >> s;
 
cout << s;
 
</pre>
 
  
The kind of resource the data affects indicates the kind of content that may be dangerous. For example, data containing special characters like period, slash, and backslash, are risky when used in methods that interact with the file system. (Resource injection, when it is related to file system resources, sometimes goes by the name "path manipulation.") Similarly, data that contains URLs and URIs is risky for functions that create remote connections.
 
  
 
==Related Threats==
 
==Related Threats==
 +
[[:Category:Logical Attacks]]
 +
 +
[[:Category: Information Disclosure]]
 +
  
 
==Related Attacks==
 
==Related Attacks==
 +
*[[Path Traversal]]
 +
*[[Path Manipulation]]
 +
*[[Relative Path Traversal]]
 +
  
 
==Related Vulnerabilities==
 
==Related Vulnerabilities==
 
[[:Category:Input Validation Vulnerability]]
 
[[:Category:Input Validation Vulnerability]]
 +
  
 
==Related Countermeasures==
 
==Related Countermeasures==
 
[[:Category:Input Validation]]
 
[[:Category:Input Validation]]
 +
  
 
==Categories==
 
==Categories==
[[Category:Injection Attack]]
+
 
[[Category:Java]]
+
[[:Category: Injection Attack]]
[[Category:Code Snippet]]
+
[[Category:Implementation]]
+

Revision as of 12:04, 14 August 2007

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


Description

This attack consists in changing resources identifiers used by application in order to perform malicious task. When an application permits a user input to define a resource, like file name or port number, this data can be manipulated to execute or access different resources.
In order to be properly executed, the attacker must have the possibility to specify a resource identifier thru application form and the application must permit its execution.

The resource type affected by user input indicates the content type that may be exposed. For example, an application that permits input of special characters like period, slash, and backslash are risky when used in methods that interact with the file system.

The resource injection attack focus on accessing other resources than local filesystem, whose is done thru a different attack technique known as Path Manipulation attack.


Examples

Example 1

The following examples represent an application which gets a port number from HTTP request and create a socket with this port number without any validation. A user using a proxy can modify this port and obtain a direct connection (socket) with the server.

Java code:

String rPort = request.getParameter("remotePort");
...
ServerSocket srvr = new ServerSocket(rPort);
Socket skt = srvr.accept(); 
...


.Net code:

int rPort = Int32.Parse(Request.get_Item("remotePort "));
...
IPEndPoint endpoint = new IPEndPoint(address,rPort);
socket = new Socket(endpoint.AddressFamily, 
SocketType.Stream, ProtocolType.Tcp);
socket.Connect(endpoint);
...


Example 2

This example is same as previous, but it gets port number from CGI requests using C++:

char* rPort = getenv("remotePort ");
...
serv_addr.sin_port = htons(atoi(rPort));
if (connect(sockfd,&serv_addr,sizeof(serv_addr)) < 0) 
error("ERROR connecting");
...


Example 3

This example in PLSQL / TSQL gets a URL path from a CGI and downloads the file contained on it. If a user modify the path or filename it’s possible to download arbitrary files from server:

...
filename := SUBSTR(OWA_UTIL.get_cgi_env('PATH_INFO'), 2);
WPG_DOCLOAD.download_file(filename); 
...


References

http://samate.nist.gov/SRD/view_testcase.php?login=Guest&tID=1734
http://cwe.mitre.org/data/definitions/99.html
http://capec.mitre.org/data/index.html#Definition
http://www.fortifysoftware.com/vulncat/
G. Hoglund and G. McGraw. Exploiting Software. Addison-Wesley, 2004.


Related Threats

Category:Logical Attacks

Category: Information Disclosure


Related Attacks


Related Vulnerabilities

Category:Input Validation Vulnerability


Related Countermeasures

Category:Input Validation


Categories

Category: Injection Attack