Command Injection is a serious cyber attack in which an attacker executes arbitrary commands on a host operating system (OS) through a vulnerable application. This attack exploits security weaknesses in an application, typically related to insufficient input validation, to run malicious commands. By manipulating inputs, such as forms or cookies, an attacker can introduce or “inject” commands that the application inadvertently executes.
The essence of command injection lies in the attacker’s ability to control the commands sent to the system. For instance, when an application passes unsafe user-supplied data (like headers, cookies, or form data) to a system shell, it can result in the execution of unintended commands. This usually occurs in web applications that fail to properly sanitize user input. When an attacker exploits this vulnerability, they can carry out actions on the server with the same privileges as the application. This can lead to various malicious activities, including data theft, website defacement, and server takeover.
Command injection attacks can manifest in different forms:
- Direct Shell Command Execution: The most straightforward form, where attackers directly input commands into form fields or through manipulated URLs, causing the server to execute them.
- Injecting Malicious Files: Attackers may inject malicious scripts or files into the server’s runtime environment. When these files are executed, they can perform harmful actions or create backdoors for further exploitation.
- Exploiting Configuration Files: Vulnerabilities in configuration files (like XML files in the case of XXE attacks) can also be exploited. Attackers manipulate these files to execute arbitrary commands or to extract data.
The impact of command injection attacks can be severe, especially if the compromised server has high privileges in the network. Protecting against such attacks involves implementing robust input validation, using secure coding practices, regularly updating and patching systems, and employing security mechanisms like Web Application Firewalls (WAFs). Awareness and proactive security measures are essential in preventing command injection vulnerabilities and safeguarding the integrity of web applications and their underlying systems.