CWE-616 上传文件变量的不完整标识（PHP）

Incomplete Identification of Uploaded File Variables (PHP)

结构: Simple

Abstraction: Variant

状态: Incomplete

被利用可能性: unkown

基本描述

The PHP application uses an old method for processing uploaded files by referencing the four global variables that are set for each file (e.g. $varname, $varname_size, $varname_name, $varname_type). These variables could be overwritten by attackers, causing the application to process unauthorized files.

扩展描述

These global variables could be overwritten by POST requests, cookies, or other methods of populating or overwriting these variables. This could be used to read or process arbitrary files by providing values such as "/etc/passwd".

相关缺陷

• cwe_Nature: ChildOf cwe_CWE_ID: 345 cwe_View_ID: 1000 cwe_Ordinal: Primary

• cwe_Nature: PeerOf cwe_CWE_ID: 473 cwe_View_ID: 1000

适用平台

Language: {'cwe_Name': 'PHP', 'cwe_Prevalence': 'Undetermined'}

常见的影响

可能的缓解方案

Architecture and Design

策略:

Use PHP 4 or later.

Architecture and Design

策略:

If you must support older PHP versions, write your own version of is_uploaded_file() and run it against $HTTP_POST_FILES['userfile']))

Implementation

策略:

For later PHP versions, reference uploaded files using the $HTTP_POST_FILES or $_FILES variables, and use is_uploaded_file() or move_uploaded_file() to ensure that you are dealing with an uploaded file.

示例代码

例

As of 2006, the "four globals" method is probably in sharp decline, but older PHP applications could have this issue.

In the "four globals" method, PHP sets the following 4 global variables (where "varname" is application-dependent):

bad PHP

例

"The global $_FILES exists as of PHP 4.1.0 (Use $HTTP_POST_FILES instead if using an earlier version). These arrays will contain all the uploaded file information."

bad PHP

** note: 'userfile' is the field name from the web form; this can vary.

分析过的案例

分类映射

引用

• REF-502 A Study in Scarlet - section 5, "File Upload"

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