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CWE-602 Clase Borrador
Client-Side Enforcement of Server-Side Security
This vulnerability occurs when a server incorrectly trusts the client to enforce critical security rules, such as input validation or access controls, instead of performing these checks itself.
Definición
What is CWE-602?
This vulnerability occurs when a server incorrectly trusts the client to enforce critical security rules, such as input validation or access controls, instead of performing these checks itself.
This flaw creates a fundamental trust issue. Since an attacker has full control over their own client—whether it's a browser, mobile app, or API client—they can easily bypass, remove, or manipulate any client-side security checks. The server, operating under the false assumption that these checks are reliable, then processes malicious or unauthorized requests.
The impact depends entirely on what the client was supposed to protect. Common consequences include unauthorized data access, privilege escalation, data corruption, or complete system compromise. The root cause is a design error: security must always be enforced at the point where trust is established and data is ultimately processed—the server.
Impacto en el mundo real
Real-world CVEs caused by CWE-602
-
SCADA system only uses client-side authentication, allowing adversaries to impersonate other users.
-
ASP program allows upload of .asp files by bypassing client-side checks.
-
steganography products embed password information in the carrier file, which can be extracted from a modified client.
-
steganography products embed password information in the carrier file, which can be extracted from a modified client.
-
client allows server to modify client's configuration and overwrite arbitrary files.
Cómo lo explotan los atacantes
Ruta del atacante paso a paso
- 1
This example contains client-side code that checks if the user authenticated successfully before sending a command. The server-side code performs the authentication in one step, and executes the command in a separate step.
- 2
CLIENT-SIDE (client.pl)
- 3
SERVER-SIDE (server.pl):
- 4
The server accepts 2 commands, "AUTH" which authenticates the user, and "CHANGE-ADDRESS" which updates the address field for the username. The client performs the authentication and only sends a CHANGE-ADDRESS for that user if the authentication succeeds. Because the client has already performed the authentication, the server assumes that the username in the CHANGE-ADDRESS is the same as the authenticated user. An attacker could modify the client by removing the code that sends the "AUTH" command and simply executing the CHANGE-ADDRESS.
- 5
In 2022, the OT:ICEFALL study examined products by 10 different Operational Technology (OT) vendors. The researchers reported 56 vulnerabilities and said that the products were "insecure by design" [REF-1283]. If exploited, these vulnerabilities often allowed adversaries to change how the products operated, ranging from denial of service to changing the code that the products executed. Since these products were often used in industries such as power, electrical, water, and others, there could even be safety implications.
Ejemplo de código vulnerable
Vulnerable Perl
SERVER-SIDE (server.pl):
$sock = acceptSocket(1234);
($cmd, $args) = ParseClientRequest($sock);
if ($cmd eq "AUTH") {
($username, $pass) = split(/\s+/, $args, 2);
$result = AuthenticateUser($username, $pass);
writeSocket($sock, "$result\n");
```
# does not close the socket on failure; assumes the*
*# user will try again*
}
elsif ($cmd eq "CHANGE-ADDRESS") {
```
if (validateAddress($args)) {
$res = UpdateDatabaseRecord($username, "address", $args);
writeSocket($sock, "SUCCESS\n");
}
else {
writeSocket($sock, "FAILURE -- address is malformed\n");
}
} Ejemplo de código seguro
Secure Perl
CLIENT-SIDE (client.pl)
$server = "server.example.com";
$username = AskForUserName();
$password = AskForPassword();
$address = AskForAddress();
$sock = OpenSocket($server, 1234);
writeSocket($sock, "AUTH $username $password\n");
$resp = readSocket($sock);
if ($resp eq "success") {
```
# username/pass is valid, go ahead and update the info!*
writeSocket($sock, "CHANGE-ADDRESS $username $address\n";}
else {
```
print "ERROR: Invalid Authentication!\n";
} What changed: the unsafe sink is replaced (or the input is validated/escaped) so the same payload no longer triggers the weakness.
Lista de prevención
How to prevent CWE-602
- Architecture and Design For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server. Even though client-side checks provide minimal benefits with respect to server-side security, they are still useful. First, they can support intrusion detection. If the server receives input that should have been rejected by the client, then it may be an indication of an attack. Second, client-side error-checking can provide helpful feedback to the user about the expectations for valid input. Third, there may be a reduction in server-side processing time for accidental input errors, although this is typically a small savings.
- Architecture and Design If some degree of trust is required between the two entities, then use integrity checking and strong authentication to ensure that the inputs are coming from a trusted source. Design the product so that this trust is managed in a centralized fashion, especially if there are complex or numerous communication channels, in order to reduce the risks that the implementer will mistakenly omit a check in a single code path.
- Testing Use dynamic tools and techniques that interact with the software using large test suites with many diverse inputs, such as fuzz testing (fuzzing), robustness testing, and fault injection. The software's operation may slow down, but it should not become unstable, crash, or generate incorrect results.
- Testing Use tools and techniques that require manual (human) analysis, such as penetration testing, threat modeling, and interactive tools that allow the tester to record and modify an active session. These may be more effective than strictly automated techniques. This is especially the case with weaknesses that are related to design and business rules.
Señales de detección
How to detect CWE-602
Ejecuta pruebas dinámicas de seguridad de aplicaciones (DAST) contra el endpoint en vivo.
Vigila los logs en tiempo de ejecución para detectar trazas de excepción inusuales, entradas malformadas o intentos de bypass de autorización.
Revisión de código: marca cualquier código nuevo que maneje entrada desde esta superficie sin usar los helpers validados del framework.
Plexicus detecta automáticamente CWE-602 y abre un PR de corrección en menos de 60 segundos.
Codex Remedium escanea cada commit, identifica esta debilidad concreta y entrega un pull request listo para revisión con el parche. Sin tickets. Sin traspasos.
Preguntas frecuentes ¿Qué es CWE-602?
¿Qué gravedad tiene CWE-602?
¿Qué lenguajes o plataformas se ven afectados por CWE-602?
¿Cómo puedo prevenir CWE-602?
¿Cómo detecta y corrige Plexicus CWE-602?
¿Dónde puedo aprender más sobre CWE-602?
Frequently asked questions
¿Qué es CWE-602?
This vulnerability occurs when a server incorrectly trusts the client to enforce critical security rules, such as input validation or access controls, instead of performing these checks itself.
¿Qué gravedad tiene CWE-602?
MITRE califica la probabilidad de explotación como Media — la explotación es realista pero suele requerir condiciones específicas.
¿Qué lenguajes o plataformas se ven afectados por CWE-602?
MITRE lists the following affected platforms: ICS/OT, Mobile.
¿Cómo puedo prevenir CWE-602?
For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server. Even though client-side checks provide minimal benefits with respect to server-side security, they are still useful. First, they can support…
¿Cómo detecta y corrige Plexicus CWE-602?
El motor SAST de Plexicus detecta la firma de flujo de datos para CWE-602 en cada commit. Cuando hay coincidencia, nuestro agente Codex Remedium abre un PR de corrección con el código corregido, las pruebas y un resumen de una línea para el revisor.
¿Dónde puedo aprender más sobre CWE-602?
MITRE publica la definición canónica en https://cwe.mitre.org/data/definitions/602.html. También puedes consultar la documentación de OWASP y NIST para guías relacionadas.
Debilidades relacionadas
Weaknesses related to CWE-602
CWE-693 Padre
Protection Mechanism Failure
This weakness occurs when software either lacks a necessary security control, implements one that is too weak, or fails to activate an…
CWE-1039 Hermano
Inadequate Detection or Handling of Adversarial Input Perturbations in Automated Recognition Mechanism
This vulnerability occurs when a system uses automated AI or machine learning to classify complex inputs like images, audio, or text, but…
CWE-1248 Hermano
Semiconductor Defects in Hardware Logic with Security-Sensitive Implications
A security-critical hardware component contains physical flaws in its semiconductor material, which can cause it to malfunction and…
CWE-1253 Hermano
Incorrect Selection of Fuse Values
This vulnerability occurs when a hardware security fuse is incorrectly programmed to represent a 'secure' state as logic 0 (unblown). An…
CWE-1269 Hermano
Product Released in Non-Release Configuration
This vulnerability occurs when a product ships to customers while still configured with its pre-production or manufacturing settings,…
CWE-1278 Hermano
Missing Protection Against Hardware Reverse Engineering Using Integrated Circuit (IC) Imaging Techniques
This vulnerability occurs when hardware lacks safeguards against physical inspection, allowing attackers to extract sensitive data by…
CWE-1291 Hermano
Public Key Re-Use for Signing both Debug and Production Code
This vulnerability occurs when the same cryptographic key is used to sign both development/debug software builds and final production…
CWE-1318 Hermano
Missing Support for Security Features in On-chip Fabrics or Buses
This vulnerability occurs when the communication channels (fabrics or buses) within a chip lack built-in or enabled security features,…
CWE-1319 Hermano
Improper Protection against Electromagnetic Fault Injection (EM-FI)
This vulnerability occurs when a hardware device lacks sufficient shielding against electromagnetic interference, allowing attackers to…
Recursos
Further reading
- MITRE — CWE-602 oficial https://cwe.mitre.org/data/definitions/602.html
- Writing Secure Code https://www.microsoftpressstore.com/store/writing-secure-code-9780735617223
- OT:ICEFALL: The legacy of "insecure by design" and its implications for certifications and risk management https://www.forescout.com/resources/ot-icefall-report/
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