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CWE-6 Variante Incompleto
J2EE Misconfiguration: Insufficient Session-ID Length
This vulnerability occurs when a J2EE application uses session identifiers that are too short, making them easier for attackers to predict or capture.
Definição
What is CWE-6?
This vulnerability occurs when a J2EE application uses session identifiers that are too short, making them easier for attackers to predict or capture.
Session IDs that are too short drastically reduce the number of possible combinations, making them vulnerable to brute-force guessing or enumeration attacks. When an attacker successfully guesses or steals a valid session ID, they can impersonate the legitimate user and hijack their active session, potentially gaining unauthorized access to sensitive data or privileged functions.
To prevent this, developers must ensure session IDs are generated with sufficient length and entropy, typically using a secure random number generator. Longer session IDs exponentially increase the possible values, making them computationally infeasible to guess and significantly raising the security barrier against session hijacking attempts.
Impacto no mundo real
Real-world CVEs caused by CWE-6
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
The following XML example code is a deployment descriptor for a Java web application deployed on a Sun Java Application Server. This deployment descriptor includes a session configuration property for configuring the session ID length.
- 2
This deployment descriptor has set the session ID length for this Java web application to 8 bytes (or 64 bits). The session ID length for Java web applications should be set to 16 bytes (128 bits) to prevent attackers from guessing and/or stealing a session ID and taking over a user's session.
- 3
Note for most application servers including the Sun Java Application Server the session ID length is by default set to 128 bits and should not be changed. And for many application servers the session ID length cannot be changed from this default setting. Check your application server documentation for the session ID length default setting and configuration options to ensure that the session ID length is set to 128 bits.
Exemplo de código vulnerável
Vulnerable XML
The following XML example code is a deployment descriptor for a Java web application deployed on a Sun Java Application Server. This deployment descriptor includes a session configuration property for configuring the session ID length.
<sun-web-app>
...
<session-config>
<session-properties>
<property name="idLengthBytes" value="8">
<description>The number of bytes in this web module's session ID.</description>
</property>
</session-properties>
</session-config>
...
</sun-web-app> Exemplo de código seguro
Secure pseudo
// Validate, sanitize, or use a safe API before reaching the sink.
function handleRequest(input) {
const safe = validateAndEscape(input);
return executeWithGuards(safe);
} 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-6
- Implementation Session identifiers should be at least 128 bits long to prevent brute-force session guessing. A shorter session identifier leaves the application open to brute-force session guessing attacks.
- Implementation A lower bound on the number of valid session identifiers that are available to be guessed is the number of users that are active on a site at any given moment. However, any users that abandon their sessions without logging out will increase this number. (This is one of many good reasons to have a short inactive session timeout.) With a 64 bit session identifier, assume 32 bits of entropy. For a large web site, assume that the attacker can try 1,000 guesses per second and that there are 10,000 valid session identifiers at any given moment. Given these assumptions, the expected time for an attacker to successfully guess a valid session identifier is less than 4 minutes. Now assume a 128 bit session identifier that provides 64 bits of entropy. With a very large web site, an attacker might try 10,000 guesses per second with 100,000 valid session identifiers available to be guessed. Given these assumptions, the expected time for an attacker to successfully guess a valid session identifier is greater than 292 years.
Sinais de deteção
How to detect CWE-6
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-6
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Perguntas frequentes O que é o CWE-6?
Qual a gravidade do CWE-6?
Que linguagens ou plataformas são afetadas pelo CWE-6?
Como posso prevenir o CWE-6?
Como é que o Plexicus deteta e corrige o CWE-6?
Onde posso saber mais sobre o CWE-6?
Frequently asked questions
O que é o CWE-6?
This vulnerability occurs when a J2EE application uses session identifiers that are too short, making them easier for attackers to predict or capture.
Qual a gravidade do CWE-6?
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-6?
MITRE lists the following affected platforms: Java.
Como posso prevenir o CWE-6?
Session identifiers should be at least 128 bits long to prevent brute-force session guessing. A shorter session identifier leaves the application open to brute-force session guessing attacks. A lower bound on the number of valid session identifiers that are available to be guessed is the number of users that are active on a site at any given moment. However, any users that abandon their sessions without logging out will increase this number. (This is one of many good reasons to have a short…
Como é que o Plexicus deteta e corrige o CWE-6?
O motor SAST do Plexicus correlaciona a assinatura de fluxo de dados do CWE-6 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-6?
A MITRE publica a definição canónica em https://cwe.mitre.org/data/definitions/6.html. Pode também consultar a documentação da OWASP e do NIST para orientações adjacentes.
Fraquezas relacionadas
Weaknesses related to CWE-6
Recursos
Further reading
- MITRE — CWE-6 oficial https://cwe.mitre.org/data/definitions/6.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
- Hold Your Sessions: An Attack on Java Session-id Generation https://www.microsoft.com/en-us/research/wp-content/uploads/2016/02/gm05.pdf
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