i春秋-fuzzing(内网ip伪造，函数传值)

练习平台地址

竞赛中心

题目描述

题目内容

打开发现说there is nothing，没有东西

F12检查也没有发现有效信息，于是看请求头

发现提示需要大的内部网络，应该是要进行XFF，BP抓包

常见的内网ip段

C类：192.168.0.0 - 192.168.255.255

B类：172.16.0.0 - 172.31.255.255

A类：10.0.0.0 - 10.255.255.255

当然这里是题目应该不会设置太复杂的，我们测试范围的开头和结尾即可

192.168.0.0

192.168.255.255

172.16.0.0

172.31.255.255

10.0.0.0

10.255.255.255

请求头

X-Custom-IP-Authorization

X-Forwarded-For

X-Forward-For

X-Remote-IP

X-Originating-IP

X-Remote-Addr

X-Client-IP

X-Real-IP

client-ip

BP爆破

访问m4nage.php

提示给他一个key

尝试传值

提示key不正确并返回了正确的key要满足的要求

key经过MD5加密之前是ichunqiu加上三位未知数，这三个可以使小写字母和数字中的任意一个，编写python脚本来进行暴力求解

md5(key)==="1b4167610ba3f2ac426a68488dbd89be",and the key is ichunqiu***,the * is in [a-z0-9]

脚本如下

python 复制代码

import hashlib
import itertools
import string

# 目标MD5哈希值
target_hash = "1b4167610ba3f2ac426a68488dbd89be"

# 定义可能的字符集，这里包含小写字母和数字
charset = string.ascii_lowercase + string.digits

# 遍历可能的长度（这里假设长度范围是1到一定数值，比如8，你可以根据实际情况调整）
for length in range(1, 8):
    # 生成所有可能的组合
    for combination in itertools.product(charset, repeat=length):
        key = "ichunqiu" + "".join(combination)
        # 计算MD5哈希值
        hash_object = hashlib.md5(key.encode())
        hash_value = hash_object.hexdigest()
        if hash_value == target_hash:
            print(f"找到匹配的key: {key}")
            break
    else:
        continue
    break

网上的脚本

python 复制代码

#!/bin/bash
import hashlib
def md5(data):
    m = hashlib.md5()
    m.update(data)
    a = m.hexdigest()
    return a

a = 'ichunqiu'
b = 'abcdefghijklmnopqrstuvwxyz1234567890'
for i in b:
    for j in b:
        for k in b:
            if md5(a+i+j+k)=='1b4167610ba3f2ac426a68488dbd89be':
                print a+i+j+k

key

ichunqiu105

访问xx00xxoo.php

source code is in the x0.txt.Can you guess the key
the authcode(flag) is 521c3EWKuGh5yBEURPzoLOuXWvj9ADEE2FBwpHyw8hVaEc2uGxQ/SdTSmIbgvQ1siJOB3JdJl8iWjAKwDTrLUec8mIoF3lM

源码如下

这应该就是一个解密函数，因为传值$operation = 'DECODE'

php 复制代码

<?php
function authcode($string, $operation = 'DECODE', $key = '', $expiry = 0)
{
    $ckey_length = 4;

    $key = md5($key ? $key : UC_KEY);
    $keya = md5(substr($key, 0, 16));
    $keyb = md5(substr($key, 16, 16));
    $keyc = $ckey_length ? ($operation == 'DECODE' ? substr($string, 0, $ckey_length) : substr(md5(microtime()), -$ckey_length)) : '';

    $cryptkey = $keya . md5($keya . $keyc);
    $key_length = strlen($cryptkey);

    $string = $operation == 'DECODE' ? base64_decode(substr($string, $ckey_length)) : sprintf('%010d', $expiry ? $expiry + time() : 0) . substr(md5($string . $keyb), 0, 16) . $string;
    $string_length = strlen($string);

    $result = '';
    $box = range(0, 255);

    $rndkey = array();
    for ($i = 0; $i <= 255; $i++) {
        $rndkey[$i] = ord($cryptkey[$i % $key_length]);
    }

    for ($j = $i = 0; $i < 256; $i++) {
        $j = ($j + $box[$i] + $rndkey[$i]) % 256;
        $tmp = $box[$i];
        $box[$i] = $box[$j];
        $box[$j] = $tmp;
    }

    for ($a = $j = $i = 0; $i < $string_length; $i++) {
        $a = ($a + 1) % 256;
        $j = ($j + $box[$a]) % 256;
        $tmp = $box[$a];
        $box[$a] = $box[$j];
        $box[$j] = $tmp;
        $result .= chr(ord($string[$i]) ^ ($box[($box[$a] + $box[$j]) % 256]));
    }

    if ($operation == 'DECODE') {
        if ((substr($result, 0, 10) == 0 || substr($result, 0, 10) - time() > 0) && substr($result, 10, 16) == substr(md5(substr($result, 26) . $keyb), 0, 16)) {
            return substr($result, 26);
        } else {
            return '';
        }
    } else {
        return $keyc . str_replace('=', '', base64_encode($result));
    }

}

传入相应参数得到flag

php 复制代码

echo authcode("521c3EWKuGh5yBEURPzoLOuXWvj9ADEE2FBwpHyw8hVaEc2uGxQ/SdTSmIbgvQ1siJOB3JdJl8iWjAKwDTrLUec8mIoF3lM",$operation = 'DECODE', $key = 'ichunqiu105', $expiry = 0);

flag

flag{3c1090ad-1bc3-47a6-a61d-2b5d0fda18da}

注意事项

在使用BP爆破内网ip时，要记得取消特殊字符编码