CWE-420 Base Rascunho

Unprotected Alternate Channel

This vulnerability occurs when an application secures its main communication path but leaves a backup or alternative channel with weaker or no protection.

Definição

What is CWE-420?

This vulnerability occurs when an application secures its main communication path but leaves a backup or alternative channel with weaker or no protection.

Think of an application that uses strong encryption for its primary web login but sends password reset codes via unencrypted SMS. An attacker can ignore the fortified main door and easily intercept data through this neglected side channel. This creates a false sense of security, as the overall system is only as strong as its weakest point. Developers often focus all their security efforts on the obvious primary path, forgetting that attackers actively seek out these alternate, less-guarded routes. To prevent this, you must perform a thorough threat model that maps all data flows, not just the primary ones. Apply consistent security controls—like encryption, authentication, and integrity checks—across every channel that handles sensitive data or critical commands. Regularly test both primary and alternate paths during security assessments to ensure your defenses are uniform and comprehensive.

Impacto no mundo real

Real-world CVEs caused by CWE-420

CVE-2020-8004

When the internal flash is protected by blocking access on the Data Bus (DBUS), it can still be indirectly accessed through the Instruction Bus (IBUS).
CVE-2002-0567

DB server assumes that local clients have performed authentication, allowing attacker to directly connect to a process to load libraries and execute commands; a socket interface also exists (another alternate channel), so attack can be remote.
CVE-2002-1578

Product does not restrict access to underlying database, so attacker can bypass restrictions by directly querying the database.
CVE-2003-1035

User can avoid lockouts by using an API instead of the GUI to conduct brute force password guessing.
CVE-2002-1863

FTP service can not be disabled even when other access controls would require it.
CVE-2002-0066

Windows named pipe created without authentication/access control, allowing configuration modification.
CVE-2004-1461

Router management interface spawns a separate TCP connection after authentication, allowing hijacking by attacker coming from the same IP address.

Como os atacantes a exploram

Trajeto do atacante passo a passo

1
Identificar um caminho de código que trata input não confiável sem validação.
2
Criar um payload que explora o comportamento inseguro — injeção, traversal, overflow ou abuso de lógica.
3
Entregar o payload através de um pedido normal e observar a reação da aplicação.
4
Iterar até que a resposta exponha dados, execute código do atacante ou escale privilégios.

Exemplo de código vulnerável

Vulnerable Verilog

Vulnerável Verilog

assign addr_auth = (address == 32'hF00) ? 1: 0;

Exemplo de código seguro

Secure Verilog

The bugged line of code is repeated in the Bad example above. The weakness arises from the fact that the SECURE_ME register can be modified by writing to the shadow register COPY_OF_SECURE_ME. The address of COPY_OF_SECURE_ME should also be included in the check. That buggy line of code should instead be replaced as shown in the Good Code Snippet below.

Seguro Verilog

assign addr_auth = (address == 32'hF00 || address == 32'h800F00) ? 1: 0;

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-420

Architecture and Design Identify all alternate channels and use the same protection mechanisms that are used for the primary channels.

Sinais de deteção

How to detect CWE-420

SAST High

Executar análise estática (SAST) na base de código à procura do padrão inseguro no fluxo de dados.

DAST Moderate

Executar testes dinâmicos de segurança de aplicações (DAST) contra o endpoint em execução.

Runtime Moderate

Monitorizar os registos em tempo de execução para traços de exceção invulgares, input malformado ou tentativas de contornar a autorização.

Code review Moderate

Revisão de código: sinalizar qualquer novo código que trate input desta superfície sem usar os ajudantes validados do framework.

CWE-420

Don't catalog this weakness. Prove it's reachable.

Plexicus turns CWE catalogs into evidence: every CWE-pattern is matched against your real code graph, reach is proven on a sandbox clone, and verified findings ship as reviewed PRs.

Request AI Swarm Pentest

Perguntas frequentes

Frequently asked questions

O que é o CWE-420?

This vulnerability occurs when an application secures its main communication path but leaves a backup or alternative channel with weaker or no protection.

Qual a gravidade do CWE-420?

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-420?

A MITRE não especificou as plataformas afetadas por este CWE — pode aplicar-se à maioria das stacks de aplicações.

Como posso prevenir o CWE-420?

Identify all alternate channels and use the same protection mechanisms that are used for the primary channels.

Como é que o Plexicus deteta e corrige o CWE-420?

O motor SAST do Plexicus correlaciona a assinatura de fluxo de dados do CWE-420 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-420?

A MITRE publica a definição canónica em https://cwe.mitre.org/data/definitions/420.html. Pode também consultar a documentação da OWASP e do NIST para orientações adjacentes.

Fraquezas relacionadas

Weaknesses related to CWE-420

CWE-923 Pai

Pronto para validar o que importa.

O Plexicus é Proof-Driven AppSec: achados validados, compreensão contextual e remediação revisada — ancorada em evidência, escopada com você.

Reservar Pentest

Unprotected Alternate Channel

What is CWE-420?

Real-world CVEs caused by CWE-420

Trajeto do atacante passo a passo

Vulnerable Verilog

Secure Verilog

How to prevent CWE-420

How to detect CWE-420

Don't catalog this weakness. Prove it's reachable.

Frequently asked questions

Weaknesses related to CWE-420

Improper Restriction of Communication Channel to Intended Endpoints

Sensitive Cookie with Improper SameSite Attribute

Reliance on IP Address for Authentication

Improper Validation of Certificate with Host Mismatch

Channel Accessible by Non-Endpoint

Unprotected Primary Channel

Improper Verification of Source of a Communication Channel

Incorrectly Specified Destination in a Communication Channel

Permissive Cross-domain Security Policy with Untrusted Domains

Further reading

Pronto para validar o que importa.

Verifique se o AI Swarm Pentest se adequa ao seu ambiente.

Pedido recebido. Marque o próximo passo.

Sample evidence handover

Server-Side Request Forgery in `webhooks/receiver`