CWE-99: Improper Control of Resource Identifiers ('Resource Injection')
Improper Control of Resource Identifiers ('Resource Injection')
Weakness ID: 99 (Weakness Base)
Status: Draft
Description
Description Summary
The software receives input from an upstream component, but it
does not restrict or incorrectly restricts the input before it is used as an
identifier for a resource that may be outside the intended sphere of
control.
Extended Description
This may enable an attacker to access or modify otherwise protected system
resources.
Time of Introduction
Architecture and Design
Implementation
Applicable Platforms
Languages
All
Likelihood of Exploit
High
Demonstrative Examples
Example 1
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.
File rFile = new File("/usr/local/apfr/reports/" + rName);
...
rFile.delete();
Example 2
The following 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.
(Bad Code)
C++
ifstream ifs(argv[0]);
string s;
ifs >> s;
cout << s;
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.
Potential Mitigations
Phase
Description
Assume all input is malicious. Use an appropriate combination of black
lists and white lists to ensure only valid and expected input is
processed by the system.
Other Notes
A resource injection issue occurs when the following two conditions are
met: 1. 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. 2. 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, run with a configuration controlled by the
attacker, or transmit sensitive information to a third-party server. Note:
Resource injection that involves resources stored on the filesystem goes by
the name path manipulation and is reported in separate category. See the
path manipulation description for further details of this vulnerability.
Weakness Ordinalities
Ordinality
Description
Primary
(where the
weakness exists independent of other weaknesses)
Description
