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Vulnerabilities

  • Introduction
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    Apex

    • Overview
    • Insecure Access Control
    • Insecure Network Communication
    • Insecure Processing of Data
    • Insecure Use of Cryptography
    • Insecure Use of Language/Framework API
    • Insecure Use of SQL Queries

    C/C++

    • Overview
    • Insecure Access Control
    • Insecure File Management
    • Insecure Processing of Data
    • Insecure Use of Cryptography
    • Insecure Use of Dangerous Function

    Dotnet

    • Overview
    • Insecure Access Control
    • Insecure Configuration
    • Insecure File Management
    • Insecure Processing of Data
    • Insecure Use of Cryptography
    • Insecure Use of Dangerous Function
    • Insecure Use of SQL Queries
    • Using Vulnerable Libraries

    Elixir

    • Overview
    • Insecure Configuration
    • Insecure File Management
    • Insecure Processing of Data
    • Insecure Network Communication
    • Insecure Use of Dangerous Function
    • Insecure Use of Language/Framework API
    • Insecure Use of SQL Queries
    • Using Vulnerable Libraries

    Go

    • Overview
    • Insecure File Management
    • Insecure Network Communication
    • Insecure Processing of Data
    • Insecure Use of Cryptography
    • Insecure Use of Dangerous Function
    • Insecure Use of SQL Queries
    • Using Vulnerable Libraries

    Java

    • Overview
    • Using Vulnerable Libraries
    • Insecure Use of SQL Queries
    • Insecure Use of Dangerous Function
    • Insecure Use of Regular Expressions
    • Insecure Authentication
    • Insecure Configuration
    • Insecure File Management
    • Insecure Use of Cryptography
    • Insecure Use of Language/Framework API
    • Insecure Processing of Data
    • Insecure Network Communication

    Javascript/TypeScript

    • Overview
    • Insecure Authentication
    • Insecure Processing of Data
    • Insecure Use of SQL Queries
    • Insecure Use of Regular Expressions
    • Insecure Use of Language/Framework API
    • Insecure Use of Dangerous Function
    • Using Vulnerable Libraries

    Kubernetes

    • Overview
    • Insecure Access Control
    • Insecure Configuration
    • Insecure Network Communication

    PHP

    • Overview
    • Insecure Configuration
    • Insecure File Management
    • Insecure Network Communication
    • Insecure Processing of Data
    • Insecure Use of Dangerous Function
    • Insecure Use of Language/Framework API
    • Insecure Use of Regular Expressions
    • Insecure Use of SQL Queries
    • Using Vulnerable Libraries

    Python

    • Overview
    • Insecure Configuration
    • Insecure Use of Cryptography
    • Insecure Network Communication
    • Insecure Processing of Data
    • Insecure Use of Dangerous Function
    • Insecure Use of SQL Queries
    • Using Vulnerable Libraries

    Ruby

    • Overview
    • Insecure Access Control
    • Insecure Configuration
    • Insecure File Management
    • Insecure Network Communication
    • Insecure Processing of Data
    • Insecure Use of Dangerous Function
    • Insecure Use of Language/Framework API
    • Insecure Use of Regular Expressions
    • Insecure Use of SQL Queries
    • Using Vulnerable Libraries

    Rust

    • Overview
    • Using Vulnerable Libraries

    Solidity

    • Overview
    • Insecure Integer Arithmetic
    • Insecure Use of Low-Level Call
    • Reliance on Insecure Random Numbers
    • State Change After External Call
    • Transaction Order Dependence
    • Unprotected Critical Function
    • Use of Insecure Function
    • Dependence on Predictable Environment Variables
    • Write to Arbitrary Storage Location
    • Call to Untrusted Contract

    Terraform

    • Overview
    • Hard-Coded Secrets
    • Insecure Access Control
    • Insecure Configuration
    • Insecure Network Communication
    • Insecure Use of Cryptography

Insecure Use of Dangerous Function

This vulnerability category covers the following issues:

  • Command Injection

Command Injection

Why is this important?

PHP, like any other programming language, has dangerous functions. If these functions are not used properly, it can have a catastrophic impact on your app. PHP offers several ways to execute operating system commands, such as:

  • backtick operator
  • exec()
  • system()
  • assert()
  • eval()

Attacker controlled input, that is processed by any of these functions, can be leveraged to gain full access to your production environment.

Check out this video for a high-level explanation:

OS Command Injection

Read below to find out how to fix this issue in your code.

Fixing Insecure Use of Dangerous Function

Option A: Escape dangerous user input

  1. Go through the issues that GuardRails identified in the PR.
  2. Locate the dangerous function. For example:
# One example is exec, but many other dangerous functions exist in PHP.
exec('./configure '.$_POST['configure_options']);
  1. Otherwise, replace the dangerous function with the following:
$command = './configure '.$_POST['configure_options'];
# For escaping whole command strings use escapeshellcmd
$escaped_command = escapeshellcmd($command);
exec($escaped_command)

or for escaping single arguments:

# For escaping single arguments escapeshellarg
$safe_command = './configure ' . escapeshellarg($_POST['configure_options']);
exec($safe_command)
  1. Test it and ensure the functionality works as expected
  2. Ship it 🚢 and relax 🌴

Option B: Remove the dangerous function

  1. Using dangerous functions should be avoided whenever possible.
If eval() is the answer, you're almost certainly asking the
wrong question. -- Rasmus Lerdorf, BDFL of PHP
  1. Go through the issues that GuardRails identified in the PR.
  2. Verify if the dangerous function is needed, or can be replaced.
  3. Remove the dangerous function
  4. Test it and ensure the functionality works as expected
  5. Ship it 🚢 and relax 🌴

More information:

  • Common Weakness Enumeration (CWE-78)
  • Common Weakness Enumeration (CWE-95)
  • OWASP Top 10 - A1 Injection
  • escapeshellarg()
  • escapeshellcmd()
← Insecure Processing of DataInsecure Use of Language/Framework API →
  • Command Injection
    • Why is this important?
    • Fixing Insecure Use of Dangerous Function
    • More information:
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