Welcome to the pit!
由于脚本迭代太多，之前的教程已经完全不适合现在的脚本的，给使用脚本的用户带来了些许障碍。我们特此根据现有版本的脚本v4.0.x重新撰写教程。
在写新版脚本之前，我们在 QQ 群里里统计了 Android 用户的版本占比，并根据统计的结果作为优化侧重点。，根据统计结果，我们侧重于高版本 Android 的优化，并推出了导致 proot 容器闪退的集成解决方案，使用户更容易的使用脚本。
建议在安装之前，先粗略的阅读一遍教程和文章底部的文档，方便在遇到问题是及时定位到相应的文档。
from Crypto.Cipher import ChaCha20_Poly1305
import os
key = os.urandom(32)
nonce = os.urandom(12)
with open('flag.txt', 'rb') as f:
plaintext = f.read()
cipher = ChaCha20_Poly1305.new(key=key, nonce=nonce)
ct, tag = cipher.encrypt_and_digest(plaintext)
print(f"Encrypted Flag: {ct.hex()}")
print(f"Tag: {tag.hex()}")
print(f"Nonce: {nonce.hex()}")
with open('key.txt', 'w') as key_file:
key_file.write(key.hex())
打开代码附件，映入眼帘的就是标记好的backdoor
// backdoor
app.post("/UserList", (req, res) => {
user = req.body;
const blacklist = ["\\u", "outputFunctionName", "localsName", "escape"];
const hacker = JSON.stringify(user);
for (const pattern of blacklist) {
if (hacker.includes(pattern)) {
res.status(200).json({ message: "hacker!" });
return;
}
}
copy(users, user);
res.status(200).json(user);
});
打开题目环境后会提示
根据题目源码，我们可以找到路径。
app.get("/login", function (req, res) {
res.render("login");
});
<?php
error_reporting(0);
if (isset($_GET['cmd'])) {
$cmd = $_GET['cmd'];
if (preg_match("/flag|cat|ls|echo|php|bash|sh|more| |less|head|tail|[\|\&\>\<]|eval|system|exec|popen|shell_exec/i", $cmd)) {
die("Blocked by security filter!");
} else {
eval($cmd);
}
} else {
highlight_file(__FILE__);
}
?>
把文件拖进 IDA 分析可得以下内容：
程序运行时，会让你输入 flag，并将你输入的文本传给一个加密算法，如果验证和已加密文本v5吻合，则提示Yeah,You get what you want!!!
我们可以观察到，验证结果在v2上，如果v2为True，则通过验证。
<?php
error_reporting(0);
class Flag {
private $flag;
public function __construct() {
$this->flag = file_get_contents('/flag');
}
public function getFlag() {
return $this->flag;
}
public function __toString() {
return "You can't directly access the flag!";
}
}
class User {
public $username;
public $isAdmin = false;
public function __construct($username) {
$this->username = $username;
}
public function __wakeup() {
if ($this->isAdmin) {
echo "Welcome, admin! Here's your flag: " . (new Flag())->getFlag();
} else {
echo "Hello, " . htmlspecialchars($this->username) . "!";
}
}
}
if (isset($_GET['data'])) {
$data = $_GET['data'];
$object = unserialize($data);
if ($object instanceof User) {
echo $object;
} else {
echo "Invalid object!";
}
} else {
highlight_file(__FILE__);
}
?>
import libnum
import gmpy2
from Crypto.Util.number import *
flag=b'ISCTF{********}'
m=bytes_to_long(flag)
p=libnum.generate_prime(1024)
q=libnum.generate_prime(1024)
n=p*q
e=0x10001
c=pow(m,e,n)
d=inverse(e,(p-1)*(q-1))
leak = (d+(pow(p,q,n)+pow(q,p,n)))%n
print("c=", c)
print("n=", n)
print("leak=", leak)
"""
c= 8989289659072309605793417141528767265266446236550650613514493589798432446586991233583435051268377555448062724563967695425657559568596372723980081067589103919296476501677424322525079257328042851349095575718347302884996529329066703597604694781627113384086536158793653551546025090807063130353950841148535682974762381044510423210397947080397718080033363000599995100765708244828566873128882878164321817156170983773105693537799111546309755235573342169431295776881832991533489235535981382958295960435126843833532716436804949502318851112378495533302256759494573250596802016112398817816155228378089079806308296705261876583997
n= 13424018200035368603483071894166480724482952594135293395398366121467209427078817227870501294732149372214083432516059795712917132804111155585926502759533393295089100965059106772393520277313184519450478832376508528256865861027444446718552169503579478134286009893965458507369983396982525906466073384013443851551139147777507283791250268462136554061959016630318688169168797939873600493494258467352326974238472394214986505312411729432927489878418792288365594455065912126527908319239444514857325441614280498882524432151918146061570116187524918358453036228204087993064505391742062288050068745930452767100091519798860487150247
leak= 9192002086528025412361053058922669469031188193149143635074798633855112230489479254740324032262690315813650428270911079121913869290893574897752990491429582640499542165616254566396564016734157323265631446079744216458719690853526969359930225042993006404843355356540487296896949431969541367144841985153231095140361069256753593550199420993461786814074270171257117410848796614931926182811404655619662690700351986753661502438299236428991412206196135090756862851230228396476709412020941670878645924203989895008014836619321109848938770269989596541278600166088022166386213646074764712810133558692545401032391239330088256431881
"""
打开 IDA，并分析代码。
int __fastcall main(int argc, const char **argv, const char **envp)
{
_BYTE buf[40]; // [rsp+0h] [rbp-30h] BYREF
char s1[8]; // [rsp+28h] [rbp-8h] BYREF
init(argc, argv, envp);
puts("welcome to isctf2024");
puts("first i need your team id");
read(0, buf, 0x30uLL);
if ( strcmp(s1, "admin") )
{
puts("no no no");
exit(0);
}
puts("ok, go on");
vuln();
return 0;
}
<?php
error_reporting(0);
highlight_file(__FILE__);
$a = "isctf2024";
$b = $_GET["b"];
@parse_str($b);
echo "小蓝鲨开始闯关，你能帮助他拿到flag吗?<br>";
if ($a[0] != 'QNKCDZO' && md5($a[0]) == md5('QNKCDZO')) {
$num = $_POST["num"];
echo "第一关有惊无险！小蓝鲨壮着胆子接着继续往下走！<br>";
if($num == 2024){
die("QAQ小蓝鲨误入陷阱，不怕，再接再厉！");
}
if(preg_match("/[a-z]/i", $num)){
die("陷阱太多QAQ");
}
if(intval($num,0) == 2024){
echo "到这了难道还要放弃吗？<br>";
if (isset($_GET['which'])){
$which = $_GET['which'];
echo "小蓝鲨貌似在哪里见过这个陷阱O.o?继续加油，还差最后一步了！";
switch ($which){
case 0:
print('QAQ');
case 1:
case 2:
require_once $which.'.php';
echo $flag;
break;
default:
echo GWF_HTML::error('PHP-0817', 'Hacker NoNoNo!', false);
break;
}
}
}
}