COMMON WEAKNESS ENUMERATIONIncomplete

CWE-621

Variable Extraction Error

The product uses external input to determine the names of variables into which information is extracted, without verifying that the names of the specified variables are valid. This could cause the program to overwrite unintended variables.

Soyutlama

Variant

Yapı

Simple

Sömürü İhtimali

Medium

Problemi anla

Problem nedir?

The product uses external input to determine the names of variables into which information is extracted, without verifying that the names of the specified variables are valid. This could cause the program to overwrite unintended variables.

Genişletilmiş açıklama

For example, in PHP, extraction can be used to provide functionality similar to register_globals, a dangerous functionality that is frequently disabled in production systems. Calling extract() or import_request_variables() without the proper arguments could allow arbitrary global variables to be overwritten, including superglobals. Similar functionality is possible in other interpreted languages, including custom languages.

Terminoloji

Alternatif adlar ve kullanım biçimleri

Variable overwrite

Kök neden

Problem nasıl ve ne zaman oluşur?

Yaşam döngüsü evresi

Implementation

Risk

Başarılı sömürü neye yol açar?

Modify Application Data

Etkilenen güvenlik alanları: Integrity

An attacker could modify sensitive data or program variables.

Savunma

Nasıl önlenir ve çözülür?

Implementation

Input Validation

Detay
Use allowlists of variable names that can be extracted.

Implementation

Refactoring

Detay
Consider refactoring your code to avoid extraction routines altogether.

Implementation

Uygulama aşaması savunması

Detay
In PHP, call extract() with options such as EXTR_SKIP and EXTR_PREFIX_ALL; call import_request_variables() with a prefix argument. Note that these capabilities are not present in all PHP versions.