Command injection refers to an attack method in which an attacker maliciously injects system commands into user input fields of web applications to manipulate and compromise the underlying operating system (OS). By embedding unintended command sequences within regular user input, attackers may gain unauthorized OS-level control, leading to severe consequences including sensitive information leakage, alteration or deletion of system files, malware infection (e.g., viruses), or exploitation as a platform for launching further cyberattacks on other systems.
Consider the following example: a script executes the command "/usr/sbin/sendmail user@f5.com " triggered by user-input email addresses. If an attacker provides malicious input such as "user@f5.com ; rm -rf /", this command potentially executes unwanted system-level operations—in this example, recursive deletion of files on the server root directory.
To prevent command injection attacks, applications must rigorously sanitize or filter user-supplied input—removing or neutralizing any attempt to supply harmful characters or commands. However, comprehensive and consistent input sanitization across all web applications presents substantial difficulties. An effective solution to this security threat involves the deployment of Web Application Firewall (WAF) technology, designed explicitly to validate and sanitize user inputs and block malicious payloads.
F5 provides robust WAF capabilities through its F5 BIG-IP product line, enabling protection against command injection and other sophisticated Web application attacks.