CWE-98: Improper Control of Filename for Include/Require Statement in PHP Program ('PHP Remote File Inclusion')

VariantDraftExploit Likelihood: High

The PHP application receives input from an upstream component, but it does not restrict or incorrectly restricts the input before its usage in "require," "include," or similar functions.

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Extended Description

In certain versions and configurations of PHP, this can allow an attacker to specify a URL to a remote location from which the product will obtain the code to execute. In other cases in association with path traversal, the attacker can specify a local file that may contain executable statements that can be parsed by PHP.

Technical Details

Structure: Simple
Vulnerability Mapping: ALLOWED

Applicable To

Languages

PHP

Platforms

Code Examples & CVEs

Demonstrative Examples

The following code, victim.php, attempts to include a function contained in a separate PHP page on the server. It builds the path to the file by using the supplied 'module_name' parameter and appending the string '/function.php' to it.

The problem with the above code is that the value of $dir is not restricted in any way, and a malicious user could manipulate the 'module_name' parameter to force inclusion of an unanticipated file. For example, an attacker could request the above PHP page (example.php) with a 'module_name' of "http://malicious.example.com" by using the following request string:

BadPHP

$dir = $_GET['module_name'];include($dir . "/function.php");

The following code, victim.php, attempts to include a function contained in a separate PHP page on the server. It builds the path to the file by using the supplied 'module_name' parameter and appending the string '/function.php' to it.

The problem with the above code is that the value of $dir is not restricted in any way, and a malicious user could manipulate the 'module_name' parameter to force inclusion of an unanticipated file. For example, an attacker could request the above PHP page (example.php) with a 'module_name' of "http://malicious.example.com" by using the following request string:

BadPHP

system($_GET['cmd']);

Observed CVE Examples (20)

Modification of assumed-immutable configuration variable in include file allows file inclusion via direct request.

Modification of assumed-immutable configuration variable in include file allows file inclusion via direct request.

Modification of assumed-immutable configuration variable in include file allows file inclusion via direct request.

Modification of assumed-immutable configuration variable in include file allows file inclusion via direct request.

Modification of assumed-immutable configuration variable in include file allows file inclusion via direct request.

Modification of assumed-immutable configuration variable in include file allows file inclusion via direct request.

Modification of assumed-immutable variable in configuration script leads to file inclusion.

PHP file inclusion.

PHP file inclusion.

PHP file inclusion.

PHP local file inclusion.

PHP remote file include.

PHP remote file include.

PHP remote file include.

PHP remote file include.

PHP remote file include.

Directory traversal vulnerability in PHP include statement.

Directory traversal vulnerability in PHP include statement.

PHP file inclusion issue, both remote and local; local include uses ".." and "%00" characters as a manipulation, but many remote file inclusion issues probably have this vector.

chain: library file sends a redirect if it is directly requested but continues to execute, allowing remote file inclusion and path traversal.

Source-backed guidance

Additional facts reviewed against primary or authoritative security sources.

Verify controls for CWE-98 with SSDF evidence

Use NIST SSDF verification and vulnerability-response practices to detect CWE-98, Improper Control of Filename for Include/Require Statement in PHP Program ('PHP Remote File Inclusion'), 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 Libraries or Frameworks controls for Improper Control of Filename for Include/Require Statement in PHP Program

MITRE associates mitigation with Architecture and Design, Operation, and Implementation; the listed strategies include Libraries or Frameworks, Enforcement by Conversion, Sandbox or Jail, and Environment Hardening; documented detection approaches include Manual Analysis, and Automated Static Analysis. Use these source-defined anchors to turn CWE-98 into implementation, review, and verification checks for the affected component.

CWE-98: Improper Control of Filename for Include/Require Statement in PHP Program ('PHP Remote File Inclusion') — MITRE CWE

Triage CWE-98 against known exploitation evidence

Use CISA's Known Exploited Vulnerabilities catalog to test whether a vulnerability mapped to CWE-98, Improper Control of Filename for Include/Require Statement in PHP Program ('PHP Remote File Inclusion'), 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-98

Apply MITRE's full root-cause mapping guidance when using CWE-98, Improper Control of Filename for Include/Require Statement in PHP Program ('PHP Remote File Inclusion'). 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-98 with root-cause mapping checks

Apply MITRE's root-cause mapping quick tips to CWE-98, Improper Control of Filename for Include/Require Statement in PHP Program ('PHP Remote File Inclusion'). 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-98: Improper Control of Filename for Include/Require Statement in PHP Program ('PHP Remote File Inclusion')?+

CWE-98: Improper Control of Filename for Include/Require Statement in PHP Program ('PHP Remote File Inclusion') is a Common Weakness Enumeration (CWE) entry maintained by MITRE. The PHP application receives input from an upstream component, but it does not restrict or incorrectly restricts the input before its usage in "require," "include," or similar functions. In certain versions and configurations of PHP, this can allow an attacker to specify a URL to a remote location from which the product will obtain the code to execute. In other cases in association with path traversal, the attacker can specify a local file that may contain executable statements that can be parsed by PHP.

What are the security consequences of Improper Control of Filename for Include/Require Statement in PHP Program ('PHP Remote File Inclusion')?+

If exploited, CWE-98 (Improper Control of Filename for Include/Require Statement in PHP Program ('PHP Remote File Inclusion')) it can compromise Integrity, Confidentiality and Availability, leading to outcomes such as Execute Unauthorized Code or Commands.

How do you prevent or mitigate Improper Control of Filename for Include/Require Statement in PHP Program ('PHP Remote File Inclusion')?+

Recommended mitigations for CWE-98 include: Develop and run your code in the most recent versions of PHP available, preferably PHP 6 or later. Many of the highly risky features in earlier PHP interpreters have been removed, restricted, or disabled by default. Set allow_url_fopen to false, which limits the ability to include files from remote locations.

How is Improper Control of Filename for Include/Require Statement in PHP Program ('PHP Remote File Inclusion') detected?+

CWE-98 can be detected using Manual Analysis and Automated Static Analysis. Combining automated tooling with manual review typically yields the best coverage.

Which programming languages are affected by Improper Control of Filename for Include/Require Statement in PHP Program ('PHP Remote File Inclusion')?+

CWE-98 commonly affects PHP. Note that weaknesses are often language-agnostic patterns, so secure coding practices apply broadly.

What are real-world examples of Improper Control of Filename for Include/Require Statement in PHP Program ('PHP Remote File Inclusion')?+

MITRE documents real CVEs mapped to CWE-98, including CVE-2004-0285, CVE-2004-0030, CVE-2004-0068, CVE-2005-2157 and CVE-2005-2162. 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-98 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.

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