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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.

+ Alternate Terms
Insecure Direct Object Reference:

OWASP uses this term, although is is effectively the same as resource injection.

+ Time of Introduction
  • Architecture and Design
  • Implementation
+ Applicable Platforms



+ Common Consequences

Technical Impact: Read application data; Modify application data; Read files or directories; Modify files or directories

An attacker could gain access to or modify sensitive data or system resources. This could allow access to protected files or directories including configuration files and files containing sensitive information.

+ Likelihood of Exploit


+ 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.

(Bad Code)
Example Language: Java 
String rName = request.getParameter("reportName");
File rFile = new File("/usr/local/apfr/reports/" + rName);

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)
Example Language: 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: Implementation

Strategy: Input Validation

Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a whitelist of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.

When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue."

Do not rely exclusively on looking for malicious or malformed inputs (i.e., do not rely on a blacklist). A blacklist is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, blacklists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.

+ 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 a separate category. See the path manipulation description for further details of this vulnerability.

+ Weakness Ordinalities
(where the weakness exists independent of other weaknesses)
+ Relationships
NatureTypeIDNameView(s) this relationship pertains toView(s)
ChildOfWeakness ClassWeakness Class20Improper Input Validation
Seven Pernicious Kingdoms (primary)700
ChildOfWeakness ClassWeakness Class74Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')
Development Concepts (primary)699
Research Concepts (primary)1000
ChildOfCategoryCategory813OWASP Top Ten 2010 Category A4 - Insecure Direct Object References
Weaknesses in OWASP Top Ten (2010) (primary)809
ChildOfCategoryCategory896SFP Cluster: Tainted Input
Software Fault Pattern (SFP) Clusters (primary)888
PeerOfWeakness ClassWeakness Class706Use of Incorrectly-Resolved Name or Reference
Research Concepts1000
CanAlsoBeWeakness ClassWeakness Class73External Control of File Name or Path
Research Concepts1000
ParentOfWeakness BaseWeakness Base641Improper Restriction of Names for Files and Other Resources
Development Concepts (primary)699
Research Concepts (primary)1000
ParentOfWeakness BaseWeakness Base694Use of Multiple Resources with Duplicate Identifier
Development Concepts (primary)699
Research Concepts (primary)1000
ParentOfWeakness BaseWeakness Base914Improper Control of Dynamically-Identified Variables
Research Concepts (primary)1000
MemberOfViewView630Weaknesses Examined by SAMATE
Weaknesses Examined by SAMATE (primary)630
MemberOfViewView884CWE Cross-section
CWE Cross-section (primary)884
+ Causal Nature


+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
7 Pernicious KingdomsResource Injection
+ White Box Definitions

A weakness where the code path has:

1. start statement that accepts input followed by

2. a statement that allocates a System Resource using name where the input is part of the name

3. end statement that accesses the System Resource where

a. the name of the System Resource violates protection

+ Maintenance Notes

The relationship between CWE-99 and CWE-610 needs further investigation and clarification. They might be duplicates. CWE-99 "Resource Injection," as originally defined in Seven Pernicious Kingdoms taxonomy, emphasizes the "identifier used to access a system resource" such as a file name or port number, yet it explicitly states that the "resource injection" term does not apply to "path manipulation," which effectively identifies the path at which a resource can be found and could be considered to be one aspect of a resource identifier. Also, CWE-610 effectively covers any type of resource, whether that resource is at the system layer, the application layer, or the code layer.

+ Content History
Submission DateSubmitterOrganizationSource
7 Pernicious KingdomsExternally Mined
Modification DateModifierOrganizationSource
2008-07-01Eric DalciCigitalExternal
updated Time_of_Introduction
2008-08-01KDM AnalyticsExternal
added/updated white box definitions
2008-09-08CWE Content TeamMITREInternal
updated Relationships, Other_Notes, Taxonomy_Mappings, Weakness_Ordinalities
2009-05-27CWE Content TeamMITREInternal
updated Description, Name
2009-07-17KDM AnalyticsExternal
Improved the White_Box_Definition
2009-07-27CWE Content TeamMITREInternal
updated White_Box_Definitions
2011-06-01CWE Content TeamMITREInternal
updated Common_Consequences, Other_Notes
2012-05-11CWE Content TeamMITREInternal
updated Common_Consequences, Relationships
2012-10-30CWE Content TeamMITREInternal
updated Potential_Mitigations
2013-02-21CWE Content TeamMITREInternal
updated Alternate_Terms, Maintenance_Notes, Other_Notes, Relationships
2013-07-17CWE Content TeamMITREInternal
updated Relationships
Previous Entry Names
Change DatePrevious Entry Name
2008-04-11Resource Injection
2009-05-27Insufficient Control of Resource Identifiers (aka 'Resource Injection')
Page Last Updated: February 18, 2014