CWE-99: Improper Control of Resource Identifiers ('Resource Injection')

Extended Description

A resource injection issue occurs when the following two conditions are met: 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, run with a configuration controlled by the attacker, or transmit sensitive information to a third-party server. This may enable an attacker to access or modify otherwise protected system resources.

Code Examples & CVEs

Demonstrative Examples

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.

BadJava

String rName = request.getParameter("reportName");File rFile = new File("/usr/local/apfr/reports/" + rName);...rFile.delete();

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.

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.

BadC++

ifstream ifs(argv[0]);string s;ifs >> s;cout << s;

Observed CVE Examples (1)

CVE-2013-4787

chain: mobile OS verifies cryptographic signature of file in an archive, but then installs a different file with the same name that is also listed in the archive.

View Details

Source-backed guidance

Additional facts reviewed against primary or authoritative security sources.

Verify controls for CWE-99 with SSDF evidence

Use NIST SSDF verification and vulnerability-response practices to detect CWE-99, Improper Control of Resource Identifiers ('Resource Injection'), throughout the product lifecycle. Derive review questions, static or dynamic checks, and negative tests from the CWE's causal behavior; define the components and lifecycle stages each check covers; and retain findings with enough evidence to distinguish the root cause from symptoms and impacts. Track escapes and false negatives, then improve the verification plan after every confirmed occurrence.

NIST SP 800-218 Secure Software Development Framework — National Institute of Standards and Technology

Apply Input Validation controls for Improper Control of Resource Identifiers ('Resource Injection')

MITRE associates mitigation with Implementation; the listed strategies include Input Validation; documented detection approaches include Automated Static Analysis. Use these source-defined anchors to turn CWE-99 into implementation, review, and verification checks for the affected component.

CWE-99: Improper Control of Resource Identifiers ('Resource Injection') — MITRE CWE

Triage CWE-99 against known exploitation evidence

Use CISA's Known Exploited Vulnerabilities catalog to test whether a vulnerability mapped to CWE-99, Improper Control of Resource Identifiers ('Resource Injection'), has evidence of exploitation in the wild. Confirm the CVE-to-CWE root-cause mapping independently before attaching the example, then capture the affected product, required action, and remediation deadline. A missing KEV match is not evidence that the weakness is unexploited, and a KEV entry must not be generalized to every occurrence of this CWE.

Known Exploited Vulnerabilities Catalog — Cybersecurity and Infrastructure Security Agency

Apply precise root-cause mapping to CWE-99

Apply MITRE's full root-cause mapping guidance when using CWE-99, Improper Control of Resource Identifiers ('Resource Injection'). Separate weakness language from attacker prerequisites and technical impact, check the entry's abstraction and vulnerability-mapping notes, and prefer the most specific Base or Variant supported by the evidence. Record the rejected alternatives and require an independent review before the mapping is used for remediation trends or program metrics.

CVE to CWE Root Cause Mapping Guidance — MITRE CWE

Validate CWE-99 with root-cause mapping checks

Apply MITRE's root-cause mapping quick tips to CWE-99, Improper Control of Resource Identifiers ('Resource Injection'). Confirm the finding describes the causal weakness rather than an impact or attack pattern, compare the abstraction and mapping notes with plausible alternatives, and have a second reviewer challenge the selection. Preserve the evidence and reasoning so recurring defects can be measured against one consistent identifier.

CVE to CWE Root Cause Mapping Quick Tips — MITRE CWE

Frequently Asked Questions

What is CWE-99: Improper Control of Resource Identifiers ('Resource Injection')?+

CWE-99: Improper Control of Resource Identifiers ('Resource Injection') is a Common Weakness Enumeration (CWE) entry maintained by MITRE. The product 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. A resource injection issue occurs when the following two conditions are met: 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, run with a configuration controlled by the attacker, or transmit sensitive information to a third-party server. This may enable an attacker to access or modify otherwise protected system resources.

What are the security consequences of Improper Control of Resource Identifiers ('Resource Injection')?+

If exploited, CWE-99 (Improper Control of Resource Identifiers ('Resource Injection')) it can compromise Confidentiality and Integrity, leading to outcomes such as Read Application Data, Modify Application Data, Read Files or Directories and Modify Files or Directories.

Which programming languages are affected by Improper Control of Resource Identifiers ('Resource Injection')?+

CWE-99 commonly affects Not Language-Specific. Note that weaknesses are often language-agnostic patterns, so secure coding practices apply broadly.

What are real-world examples of Improper Control of Resource Identifiers ('Resource Injection')?+

MITRE documents real CVEs mapped to CWE-99, including CVE-2013-4787. You can look up the full details of each CVE, including CVSS scores and remediation guidance, on our CVE Lookup tool.

What is the difference between a CWE and a CVE?+

A CWE (Common Weakness Enumeration) like CWE-99 describes a category of software weakness — the underlying flaw type. A CVE (Common Vulnerabilities and Exposures) identifies a specific, real-world vulnerability in a particular product. In short, a CWE is the kind of mistake, and a CVE is an instance of that mistake being found in software.

CWE-99: Improper Control of Resource Identifiers ('Resource Injection')

Extended Description

Technical Details

Applicable To

Security Consequences

Scope

Impact

Mitigation Strategies

Detection Methods