CWE-477 Base Borrador

Use of Obsolete Function

This vulnerability occurs when code relies on deprecated or obsolete functions, indicating outdated practices and insufficient maintenance that can introduce security gaps.

Definición

What is CWE-477?

This vulnerability occurs when code relies on deprecated or obsolete functions, indicating outdated practices and insufficient maintenance that can introduce security gaps.
Programming languages evolve, and functions become obsolete for several key reasons: language advancements, better understanding of secure and efficient operations, and shifting conventions. These deprecated functions are typically replaced by newer, more secure alternatives designed to perform the same tasks more effectively. Using obsolete functions is a clear signal that code hasn't been actively reviewed or updated. This neglect can expose applications to unnecessary risks, as newer functions often address known security flaws, performance issues, or compatibility problems present in their older counterparts.
Impacto en el mundo real

Real-world CVEs caused by CWE-477

Todavía no hay CVEs públicos enlazados a esta CWE en el catálogo de MITRE.

Cómo lo explotan los atacantes

Ruta del atacante paso a paso

  1. 1

    The following code uses the deprecated function getpw() to verify that a plaintext password matches a user's encrypted password. If the password is valid, the function sets result to 1; otherwise it is set to 0.

  2. 2

    Although the code often behaves correctly, using the getpw() function can be problematic from a security standpoint, because it can overflow the buffer passed to its second parameter. Because of this vulnerability, getpw() has been supplanted by getpwuid(), which performs the same lookup as getpw() but returns a pointer to a statically-allocated structure to mitigate the risk. Not all functions are deprecated or replaced because they pose a security risk. However, the presence of an obsolete function often indicates that the surrounding code has been neglected and may be in a state of disrepair. Software security has not been a priority, or even a consideration, for very long. If the program uses deprecated or obsolete functions, it raises the probability that there are security problems lurking nearby.

  3. 3

    In the following code, the programmer assumes that the system always has a property named "cmd" defined. If an attacker can control the program's environment so that "cmd" is not defined, the program throws a null pointer exception when it attempts to call the "Trim()" method.

  4. 4

    The following code constructs a string object from an array of bytes and a value that specifies the top 8 bits of each 16-bit Unicode character.

  5. 5

    In this example, the constructor may not correctly convert bytes to characters depending upon which charset is used to encode the string represented by nameBytes. Due to the evolution of the charsets used to encode strings, this constructor was deprecated and replaced by a constructor that accepts as one of its parameters the name of the charset used to encode the bytes for conversion.

Ejemplo de código vulnerable

Vulnerable C

The following code uses the deprecated function getpw() to verify that a plaintext password matches a user's encrypted password. If the password is valid, the function sets result to 1; otherwise it is set to 0.

Vulnerable C 
...
  getpw(uid, pwdline);
  for (i=0; i<3; i++){
  	cryptpw=strtok(pwdline, ":");
  	pwdline=0;
  }
  result = strcmp(crypt(plainpw,cryptpw), cryptpw) == 0;
  ...
Ejemplo de código seguro

Secure pseudo

Seguro 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-477

  • Implementation Refer to the documentation for the obsolete function in order to determine why it is deprecated or obsolete and to learn about alternative ways to achieve the same functionality.
  • Requirements Consider seriously the security implications of using an obsolete function. Consider using alternate functions.
Señales de detección

How to detect CWE-477

Automated Static Analysis - Binary or Bytecode High

According to SOAR [REF-1479], the following detection techniques may be useful: ``` Highly cost effective: ``` Binary / Bytecode Quality Analysis ``` Cost effective for partial coverage: ``` Bytecode Weakness Analysis - including disassembler + source code weakness analysis

Manual Static Analysis - Binary or Bytecode SOAR Partial

According to SOAR [REF-1479], the following detection techniques may be useful: ``` Cost effective for partial coverage: ``` Binary / Bytecode disassembler - then use manual analysis for vulnerabilities & anomalies

Dynamic Analysis with Manual Results Interpretation High

According to SOAR [REF-1479], the following detection techniques may be useful: ``` Highly cost effective: ``` Debugger

Manual Static Analysis - Source Code High

According to SOAR [REF-1479], the following detection techniques may be useful: ``` Highly cost effective: ``` Manual Source Code Review (not inspections) ``` Cost effective for partial coverage: ``` Focused Manual Spotcheck - Focused manual analysis of source

Automated Static Analysis - Source Code High

According to SOAR [REF-1479], the following detection techniques may be useful: ``` Highly cost effective: ``` Source Code Quality Analyzer Source code Weakness Analyzer Context-configured Source Code Weakness Analyzer

Automated Static Analysis High

According to SOAR [REF-1479], the following detection techniques may be useful: ``` Highly cost effective: ``` Origin Analysis

Auto-corrección de Plexicus

Plexicus detecta automáticamente CWE-477 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.

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Preguntas frecuentes

Frequently asked questions

¿Qué es CWE-477?

This vulnerability occurs when code relies on deprecated or obsolete functions, indicating outdated practices and insufficient maintenance that can introduce security gaps.

¿Qué gravedad tiene CWE-477?

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-477?

MITRE no ha especificado plataformas afectadas para esta CWE — puede aplicar a la mayoría de los stacks de aplicaciones.

¿Cómo puedo prevenir CWE-477?

Refer to the documentation for the obsolete function in order to determine why it is deprecated or obsolete and to learn about alternative ways to achieve the same functionality. Consider seriously the security implications of using an obsolete function. Consider using alternate functions.

¿Cómo detecta y corrige Plexicus CWE-477?

El motor SAST de Plexicus detecta la firma de flujo de datos para CWE-477 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-477?

MITRE publica la definición canónica en https://cwe.mitre.org/data/definitions/477.html. También puedes consultar la documentación de OWASP y NIST para guías relacionadas.

Debilidades relacionadas

Weaknesses related to CWE-477

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Recursos

Further reading

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