CWE-914 动态识别变量的控制不恰当

Improper Control of Dynamically-Identified Variables

结构: Simple

Abstraction: Base

状态: Incomplete

被利用可能性: unkown

基本描述

The software does not properly restrict reading from or writing to dynamically-identified variables.

扩展描述

Many languages offer powerful features that allow the programmer to access arbitrary variables that are specified by an input string. While these features can offer significant flexibility and reduce development time, they can be extremely dangerous if attackers can modify unintended variables that have security implications.

相关缺陷

  • cwe_Nature: ChildOf cwe_CWE_ID: 99 cwe_View_ID: 1000 cwe_Ordinal: Primary

  • cwe_Nature: ChildOf cwe_CWE_ID: 99 cwe_View_ID: 699

  • cwe_Nature: ChildOf cwe_CWE_ID: 913 cwe_View_ID: 1000

  • cwe_Nature: ChildOf cwe_CWE_ID: 913 cwe_View_ID: 699 cwe_Ordinal: Primary

常见的影响

范围 影响 注释
Integrity Modify Application Data An attacker could modify sensitive data or program variables.
Integrity Execute Unauthorized Code or Commands
['Other', 'Integrity'] ['Varies by Context', 'Alter Execution Logic']

可能的缓解方案

Implementation

策略: Input Validation

For any externally-influenced input, check the input against a white list of internal program variables that are allowed to be modified.

['Implementation', 'Architecture and Design']

策略: Refactoring

Refactor the code so that internal program variables do not need to be dynamically identified.

示例代码

例

This code uses the credentials sent in a POST request to login a user.

bad PHP

//Log user in, and set $isAdmin to true if user is an administrator

function login($user,$pass){
$query = buildQuery($user,$pass);
mysql_query($query);
if(getUserRole($user) == "Admin"){
$isAdmin = true;
}
}

$isAdmin = false;
extract($_POST);
login(mysql_real_escape_string($user),mysql_real_escape_string($pass));

The call to extract() will overwrite the existing values of any variables defined previously, in this case $isAdmin. An attacker can send a POST request with an unexpected third value "isAdmin" equal to "true", thus gaining Admin privileges.

分析过的案例

标识 说明 链接
CVE-2006-7135 extract issue enables file inclusion https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-7135
CVE-2006-7079 extract used for register_globals compatibility layer, enables path traversal https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-7079
CVE-2007-0649 extract() buried in include files makes post-disclosure analysis confusing; original report had seemed incorrect. https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2007-0649
CVE-2006-6661 extract() enables static code injection https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-6661
CVE-2006-2828 import_request_variables() buried in include files makes post-disclosure analysis confusing https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-2828
CVE-2009-0422 Chain: Dynamic variable evaluation allows resultant remote file inclusion and path traversal. https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2009-0422
CVE-2007-2431 Chain: dynamic variable evaluation in PHP program used to modify critical, unexpected $_SERVER variable for resultant XSS. https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2007-2431
CVE-2006-4904 Chain: dynamic variable evaluation in PHP program used to conduct remote file inclusion. https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-4904
CVE-2006-4019 Dynamic variable evaluation in mail program allows reading and modifying attachments and preferences of other users. https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-4019