Resource Injection

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.

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); ...

Related Threats
Category:Logical Attacks

Category: Information Disclosure

Related Attacks

 * Path Traversal
 * Path Manipulation
 * Relative Path Traversal

Related Vulnerabilities
Category:Input Validation Vulnerability

Related Countermeasures
Category:Input Validation

Categories
Category: Injection Attack