Ejecuta análisis estático (SAST) sobre el código buscando el patrón inseguro en el flujo de datos.
CWE-143 Variante Borrador
Improper Neutralization of Record Delimiters
This vulnerability occurs when an application fails to properly sanitize or escape special characters that function as record separators in data streams. When untrusted input containing these…
Definición
What is CWE-143?
This vulnerability occurs when an application fails to properly sanitize or escape special characters that function as record separators in data streams. When untrusted input containing these delimiters is passed to a downstream system, it can corrupt data structures, cause misinterpretation of records, or trigger unauthorized actions.
Imagine your application accepts user input—like a form field for a name or address—and later packages that data into a structured format like a CSV file, a log entry, or a protocol message. If an attacker submits input containing a record delimiter (such as a newline, pipe character, or custom separator), and your code doesn't neutralize it, that input can break the expected record boundaries. The downstream parser, whether it's a database, a reporting tool, or another service, will then misinterpret where one record ends and the next begins, leading to data corruption, injection of false records, or logic errors.
In practice, this flaw allows data to escape its intended context. For example, a single input field could be parsed as multiple separate records, or critical delimiters could be missing, causing entire records to be merged or skipped. To prevent this, you must always validate and sanitize input by escaping or removing delimiter characters based on the specific data format and context before processing or transmitting the data.
Impacto en el mundo real
Real-world CVEs caused by CWE-143
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Carriage returns in subject field allow adding new records to data file.
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Attacker inserts carriage returns and "|" field separator characters to add new user/privileges.
Cómo lo explotan los atacantes
Ruta del atacante paso a paso
- 1
Identifica una ruta de código que maneje entrada no confiable sin validación.
- 2
Crea un payload que ejercite el comportamiento inseguro — inyección, traversal, overflow o abuso de lógica.
- 3
Envía el payload a través de una solicitud normal y observa la reacción de la aplicación.
- 4
Itera hasta que la respuesta filtre datos, ejecute código del atacante o escale privilegios.
Ejemplo de código vulnerable
Vulnerable pseudo
MITRE no ha publicado un ejemplo de código para esta CWE. El patrón siguiente es ilustrativo — consulta Recursos para referencias canónicas.
// Example pattern — see MITRE for the canonical references.
function handleRequest(input) {
// Untrusted input flows directly into the sensitive sink.
return executeUnsafe(input);
} Ejemplo 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 prevención
How to prevent CWE-143
- Developers should anticipate that record delimiters will be injected/removed/manipulated in the input vectors of their product. Use an appropriate combination of denylists and allowlists to ensure only valid, expected and appropriate input is processed by the system.
- Implementation Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does. When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue." Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
- Implementation While it is risky to use dynamically-generated query strings, code, or commands that mix control and data together, sometimes it may be unavoidable. Properly quote arguments and escape any special characters within those arguments. The most conservative approach is to escape or filter all characters that do not pass an extremely strict allowlist (such as everything that is not alphanumeric or white space). If some special characters are still needed, such as white space, wrap each argument in quotes after the escaping/filtering step. Be careful of argument injection (CWE-88).
- Implementation Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174). Such errors could be used to bypass allowlist validation schemes by introducing dangerous inputs after they have been checked.
Señales de detección
How to detect CWE-143
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-143 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-143?
¿Qué gravedad tiene CWE-143?
¿Qué lenguajes o plataformas se ven afectados por CWE-143?
¿Cómo puedo prevenir CWE-143?
¿Cómo detecta y corrige Plexicus CWE-143?
¿Dónde puedo aprender más sobre CWE-143?
Frequently asked questions
¿Qué es CWE-143?
This vulnerability occurs when an application fails to properly sanitize or escape special characters that function as record separators in data streams. When untrusted input containing these delimiters is passed to a downstream system, it can corrupt data structures, cause misinterpretation of records, or trigger unauthorized actions.
¿Qué gravedad tiene CWE-143?
MITRE no ha publicado una calificación de probabilidad de explotación para esta debilidad. Trátala como de impacto medio hasta que tu modelo de amenazas demuestre lo contrario.
¿Qué lenguajes o plataformas se ven afectados por CWE-143?
MITRE no ha especificado plataformas afectadas para esta CWE — puede aplicar a la mayoría de los stacks de aplicaciones.
¿Cómo puedo prevenir CWE-143?
Developers should anticipate that record delimiters will be injected/removed/manipulated in the input vectors of their product. Use an appropriate combination of denylists and allowlists to ensure only valid, expected and appropriate input is processed by the system. Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications,…
¿Cómo detecta y corrige Plexicus CWE-143?
El motor SAST de Plexicus detecta la firma de flujo de datos para CWE-143 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-143?
MITRE publica la definición canónica en https://cwe.mitre.org/data/definitions/143.html. También puedes consultar la documentación de OWASP y NIST para guías relacionadas.
Debilidades relacionadas
Weaknesses related to CWE-143
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