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CWE-105 Variante Rascunho
Struts: Form Field Without Validator
This vulnerability occurs when a Struts application form contains an input field that lacks a corresponding validator, leaving it open to unverified user input.
Definição
What is CWE-105?
This vulnerability occurs when a Struts application form contains an input field that lacks a corresponding validator, leaving it open to unverified user input.
Leaving even one form field without validation creates a direct opening for attackers. They can exploit this oversight to inject malicious data, bypass security checks, or manipulate application logic, potentially leading to data breaches, unauthorized access, or system compromise.
While Java applications themselves are often protected from low-level memory issues, the risk escalates if the application interacts with native code or external systems. An attacker could use this unvalidated input as an entry point to trigger buffer overflows or other critical vulnerabilities in those connected components, turning a simple input oversight into a severe chained attack.
Impacto no mundo real
Real-world CVEs caused by CWE-105
Ainda não há referências CVE públicas associadas a este CWE no catálogo da MITRE.
Como os atacantes a exploram
Trajeto do atacante passo a passo
- 1
In the following example the Java class RegistrationForm is a Struts framework ActionForm Bean that will maintain user input data from a registration webpage for an online business site. The user will enter registration data and, through the Struts framework, the RegistrationForm bean will maintain the user data in the form fields using the private member variables. The RegistrationForm class uses the Struts validation capability by extending the ValidatorForm class and including the validation for the form fields within the validator XML file, validator.xml.
- 2
The validator XML file, validator.xml, provides the validation for the form fields of the RegistrationForm.
- 3
However, in the previous example the validator XML file, validator.xml, does not provide validators for all of the form fields in the RegistrationForm. Validator forms are only provided for the first five of the seven form fields. The validator XML file should contain validator forms for all of the form fields for a Struts ActionForm bean. The following validator.xml file for the RegistrationForm class contains validator forms for all of the form fields.
Exemplo de código vulnerável
Vulnerable XML
The validator XML file, validator.xml, provides the validation for the form fields of the RegistrationForm.
<form-validation>
<formset>
<form name="RegistrationForm">
<field property="name" depends="required">
<arg position="0" key="prompt.name"/>
</field>
<field property="address" depends="required">
<arg position="0" key="prompt.address"/>
</field>
<field property="city" depends="required">
<arg position="0" key="prompt.city"/>
</field>
<field property="state" depends="required,mask">
<arg position="0" key="prompt.state"/>
<var>
<var-name>mask</var-name>
<var-value>[a-zA-Z]{2}</var-value>
</var>
</field>
<field property="zipcode" depends="required,mask">
<arg position="0" key="prompt.zipcode"/>
<var>
<var-name>mask</var-name>
<var-value>\d{5}</var-value>
</var>
</field>
</form>
</formset>
</form-validation> Exemplo de código seguro
Secure XML
However, in the previous example the validator XML file, validator.xml, does not provide validators for all of the form fields in the RegistrationForm. Validator forms are only provided for the first five of the seven form fields. The validator XML file should contain validator forms for all of the form fields for a Struts ActionForm bean. The following validator.xml file for the RegistrationForm class contains validator forms for all of the form fields.
<form-validation>
<formset>
<form name="RegistrationForm">
<field property="name" depends="required">
<arg position="0" key="prompt.name"/>
</field>
<field property="address" depends="required">
<arg position="0" key="prompt.address"/>
</field>
<field property="city" depends="required">
<arg position="0" key="prompt.city"/>
</field>
<field property="state" depends="required,mask">
<arg position="0" key="prompt.state"/>
<var>
<var-name>mask</var-name>
<var-value>[a-zA-Z]{2}</var-value>
</var>
</field>
<field property="zipcode" depends="required,mask">
<arg position="0" key="prompt.zipcode"/>
<var>
<var-name>mask</var-name>
<var-value>\d{5}</var-value>
</var>
</field>
<field property="phone" depends="required,mask">
<arg position="0" key="prompt.phone"/>
<var>
<var-name>mask</var-name>
<var-value>^([0-9]{3})(-)([0-9]{4}|[0-9]{4})$</var-value>
</var>
</field>
<field property="email" depends="required,email">
<arg position="0" key="prompt.email"/>
</field>
</form>
</formset>
</form-validation> What changed: the unsafe sink is replaced (or the input is validated/escaped) so the same payload no longer triggers the weakness.
Lista de verificação de prevenção
How to prevent CWE-105
- Implementation Validate all form fields. If a field is unused, it is still important to constrain it so that it is empty or undefined.
Sinais de deteção
How to detect CWE-105
Executar testes dinâmicos de segurança de aplicações (DAST) contra o endpoint em execução.
Monitorizar os registos em tempo de execução para traços de exceção invulgares, input malformado ou tentativas de contornar a autorização.
Revisão de código: sinalizar qualquer novo código que trate input desta superfície sem usar os ajudantes validados do framework.
CWE-105
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Perguntas frequentes O que é o CWE-105?
Qual a gravidade do CWE-105?
Que linguagens ou plataformas são afetadas pelo CWE-105?
Como posso prevenir o CWE-105?
Como é que o Plexicus deteta e corrige o CWE-105?
Onde posso saber mais sobre o CWE-105?
Frequently asked questions
O que é o CWE-105?
This vulnerability occurs when a Struts application form contains an input field that lacks a corresponding validator, leaving it open to unverified user input.
Qual a gravidade do CWE-105?
A MITRE não publicou uma classificação de probabilidade de exploração para esta fraqueza. Trate-a como impacto médio até o seu modelo de ameaças provar o contrário.
Que linguagens ou plataformas são afetadas pelo CWE-105?
MITRE lists the following affected platforms: Java.
Como posso prevenir o CWE-105?
Validate all form fields. If a field is unused, it is still important to constrain it so that it is empty or undefined.
Como é que o Plexicus deteta e corrige o CWE-105?
O motor SAST do Plexicus correlaciona a assinatura de fluxo de dados do CWE-105 em cada commit. Quando é encontrada uma correspondência, o nosso agente Codex Remedium abre um PR de correção com o código corrigido, testes e um resumo de uma linha para o revisor.
Onde posso saber mais sobre o CWE-105?
A MITRE publica a definição canónica em https://cwe.mitre.org/data/definitions/105.html. Pode também consultar a documentação da OWASP e do NIST para orientações adjacentes.
Fraquezas relacionadas
Weaknesses related to CWE-105
CWE-1173 Pai
Improper Use of Validation Framework
This vulnerability occurs when a software application either fails to use or incorrectly implements a built-in or library-provided input…
CWE-102 Irmão
Struts: Duplicate Validation Forms
This vulnerability occurs when an application defines multiple Struts validation forms with identical names. The framework then…
CWE-106 Irmão
Struts: Plug-in Framework not in Use
This weakness occurs when a Java application, particularly one using the Struts framework, does not implement a structured input…
CWE-108 Irmão
Struts: Unvalidated Action Form
In Apache Struts, every Action Form that processes user input must have a corresponding validation form configured. Missing this…
CWE-109 Irmão
Struts: Validator Turned Off
This vulnerability occurs when an application built with Apache Struts intentionally disables its built-in validation framework. By…
CWE-1174 Irmão
ASP.NET Misconfiguration: Improper Model Validation
This vulnerability occurs when an ASP.NET application either completely bypasses the built-in model validation system or implements it…
CWE-554 Irmão
ASP.NET Misconfiguration: Not Using Input Validation Framework
This vulnerability occurs when an ASP.NET application fails to implement a structured input validation framework, relying instead on…
Recursos
Further reading
- MITRE — CWE-105 oficial https://cwe.mitre.org/data/definitions/105.html
- Seven Pernicious Kingdoms: A Taxonomy of Software Security Errors https://samate.nist.gov/SSATTM_Content/papers/Seven%20Pernicious%20Kingdoms%20-%20Taxonomy%20of%20Sw%20Security%20Errors%20-%20Tsipenyuk%20-%20Chess%20-%20McGraw.pdf
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