前言

第一次参加CTF比赛，感觉自己好菜（我就学了一个月而已…菜也正常）。
（以后一定要记得每次做完就写wp… 不然最后一天很难受）
TSCTF-J比赛网址

EasyXoreasyXor.rar

这题没啥说的，标准的异或出flag

enflag = [62,58,41,57,44,84,54,28,58,99,34,60,98,9,20,56,78,31,32,52,74,13,27,48,37,36,29,97,101]
decode = "abcdefghijklmnopqrstuvwxyz!!!"
for i in range(len(enflag)):
    print(chr((enflag[i]-9)^ord(decode[i])),end="")

得到flag: TSCTF-J{X0r_4nd_4dd_4re_ea5y}

从下载开始welcome.rar

用虚拟机运行一次，出现merak.png，扫描并关注公众号后回复TSCTF-J得到flag

得到flag: TSCTF-J{Welcome_to_TSCTF-J_2020}

PACMANPACMAN.zip

用dnSpy打开Assembly-CSharp.dll，找到关键语句，直接复制再运行一次就出来了
dnSpy下载地址

Exp脚本

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Security.Cryptography;
using System.IO;

namespace ConsoleApp1
{
    class Program
    {
        public static string GenerateMd5(string text)
        {
            string result;
            using (MD5 md = MD5.Create())
            {
                byte[] bytes = Encoding.Default.GetBytes(text);
                byte[] array = md.ComputeHash(bytes);
                StringBuilder stringBuilder = new StringBuilder();
                for (int i = 0; i < array.Length; i++)
                {
                    stringBuilder.Append(array[i].ToString("x2"));
                }
                result = stringBuilder.ToString();
            }
            return result;
        }

        public static string DesDecrypt(string key, string iv)
        {
            byte[] bytes = Encoding.UTF8.GetBytes(key);
            byte[] bytes2 = Encoding.UTF8.GetBytes(iv);
            string s = "eqwLr9Qh7qNMVaNd78tRy1tUdJa4eG48C9vIB+FVPTcjDf+RKofGrA==";
            DESCryptoServiceProvider descryptoServiceProvider = new DESCryptoServiceProvider();
            string result;
            using (MemoryStream memoryStream = new MemoryStream())
            {
                byte[] array = Convert.FromBase64String(s);
                try
                {
                    using (CryptoStream cryptoStream = new CryptoStream(memoryStream, descryptoServiceProvider.CreateDecryptor(bytes, bytes2), CryptoStreamMode.Write))
                    {
                        cryptoStream.Write(array, 0, array.Length);
                        cryptoStream.FlushFinalBlock();
                    }
                    result = Encoding.UTF8.GetString(memoryStream.ToArray());
                }
                catch
                {
                    result = "Oho!You are caught by me!";
                }
            }
            return result;
        }


        static void Main(string[] args)
        {
            int Eat = 0;
            string secret = "937d05a262a8a9efb9ceb2dac317fc2982e4d1bb";
            while (true)
            {
                Eat++;
                if (Eat % 100 == 0)
                {
                    secret = GenerateMd5(secret) + secret;
                    Console.WriteLine("hello1");
                }
                else if (Eat == 574)
                {
                    secret = GenerateMd5(secret);
                    secret = DesDecrypt(secret.Substring(0, 8),secret.Substring(24));
                    Console.WriteLine(secret);
                    if ((int)(secret[8] * secret[13] * secret[15]) != 486400)
                    {
                        Console.WriteLine(secret);
                    }
                    break;
                }
            }
            Console.ReadKey();
        }
    }
}

得到flag: TSCTF-J{P4c_m@n_1s_s0_1nT3rested}

Go_down_1000_floorsGo_1000_floors.zip

秒解了…直接Notepad++查找TSCTF-J就找到flag了

得到flag: TSCTF-J{Y0u_4re_a_rea1_man}

easyASM

这题让我好好的学了一次汇编，直接照着汇编自己手打一次python

原python脚本

import dis

def a(i):
    return len(i)

def b(i):
    if i[:8] != "TSCTF-J{": return False
    if i[-1:] != "}": return False
    return True

def c(i):
    l = a(i)
    b = []
    for j in range(l):
        print(i[j])
        i[j] = (i[j] + 128) % 256
    return bytes(i)


def e(f):
    o = []
    l = a(f)
    for i in range(l):
        w = ord(f[i]) ^ ord(f[(i+4)%l])
        o.append(w)
    return c(o)


def main():
    s = input("Guess\n>>")
    o = b'\xa9\x9a\xbf\xb6\x90\xea\x9f\xb1\xd9\xec\x8a\xa0\x80\x9a\xa6\x8a\xd8\x89\xbe\xca\xbe\xb7\xab\x9e\x94\xaf\x89\xfe\x92'
    if e(s) == o and b(s): print("Correct")
    else: print("Wrong...")

解密原理

根据加密原理，加密第一位要用第四位，加密第二位要用第五位，加密最后一位；又因为已知flag头尾一定是TSCTF{}，所以能直接反推得到flag

for i in range(24):
    print((i+4)%l,end=" ")
#输出：4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 0 1 2 3

Exp脚本

enflag = b'\xa9\x9a\xbf\xb6\x90\xea\x9f\xb1\xd9\xec\x8a\xa0\x80\x9a\xa6\x8a\xd8\x89\xbe\xca\xbe\xb7\xab\x9e\x94\xaf\x89\xfe\x92'
key = []
flag = [84,83,67,84,70,45,74,123,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,125] # TSCTF{}
l = len(enflag)

for i in range(l):
    key.append(enflag[l-i-1] - 128)

for i in range(l):
    k = ((l-i-1)+4)%l
    flag[l-i-1] = key[l-i-1]^flag[k]

test_flag = []
for i in range(l):
    test_flag.append(chr(flag[i]))
    print(chr(flag[i]),end="")

得到flag: TSCTF-J{R3aLly_E4sy_4Ss3mblY}

PaintUpxPaintUpx.rar

运行一下发现flag是用命令行画出来的，但到后面就卡住不输出了（WOW！便秘的感觉~~）

分析

PaintUpx名如其名，用upx加壳了，脱壳后开始分析主函数

点进sub_4016CB函数发现Sleep函数，说不定nop掉就完事？（还真是这样）

Patch

点击Edit > Patch program > Assemble 编辑汇编

点击Edit > Patch program > Apply pathes to input file > OK patch成功
patch后的exe: PaintUpx_crack.rar
运行得到flag: TSCTF-J{So_E@SY_paINt_GAmE!!?}

ZBR想要请客

分析js代码，设置断点，修改totalWrong使if命令不成立即可


得到flag: TSCTF-J{R1ch_Ric1n_ZBR_D1nn3r!}

EasyF12

没什么好说的，就普通js断点…
主页找到源码找到game1.html，进入game1.html找到game2.php，在game2.php下断点js

进入gethint.php?q=9999发现需要进入fina1.php，f12查看代码

经典md5碰撞问题，postman解决

得到flag: TSCTF-J{Welc0me_To_tHe_wor1d_0f_Web}

宣讲会

白嫖宣讲会 知乎链接
得到flag: TSCTF-J{消磨这一身魂也陪你闯}

EasyVerify

node.js运行调试即可获得flag

得到flag: TSCTF-J{Yoshino-s_want_1_girlfriend}

那你能帮帮我吗

#!/usr/bin/env python3
from secret import flag, secret_number_you_never_know

print("Source code:")
with open("main.py") as f:
    print(f.read())

print("")
try:
    val = 0
    inp = input("Input value: ")
    count_digits = len(set(inp))
    if count_digits <= 10:
        val = eval(inp)
    else:
        raise

    if val == secret_number_you_never_know: # I am very sure it is a int
        print(flag)
    else:
        print("Nope. Better luck next time.")
except:
    print("Nope. No hacking.")
    exit(1)

print(vars())可得flag

得到flag: TSCTF-J{Y_laoshi_want_girl_pengyou_qq_1735439536}

奇特的解法

输入exec(input())可以无限构造长度，感觉这个方法以后可以经常用

资源小能手

题目文件
题目百度网盘 提取码2ser
百度网盘全选文件下载，发现密码是2815e9c7290f40897da2c359ccd5029e
解压后的压缩包flag.tar.gz用010 Editor打开，发现flag

得到flag: MIXCTF{Y_la0sh1_1s_Old_driu3R}

fxxkfxxk.rar

动调后发现加密规律，直接得到exp脚本

enflag = [
  0x54, 0x52, 0x41, 0x57, 0x42, 0x28, 0x4C, 0x7C, 0x5E, 0x6C, 
  0x78, 0x72, 0x53, 0x68, 0x6F, 0x7C, 0x69, 0x4E, 0x54, 0x4B, 
  0x4C, 0x4C, 0x49, 0x45, 0x7D, 0x6F, 0x7F, 0x69, 0x6F, 0x78, 
  0x41, 0x2E, 0x11, 0x15, 0x17, 0x12, 0x10, 0x58
]
for i in range(38):
    print(chr(i^enflag[i]),end="")

得到flag: TSCTF-J{Very_easy_FXXY_Reverse_114514}

playWithMe

分析

题目附件playWithMe.pyc，用uncompyle6得到python脚本

def a(i):
    return len(i)


def c(i):
    l = a(i)
    for j in range(l):
        i[j] = (ord(i[j]) + 128) % 256
    else:
        return bytes(i)[::-1]


def e(f):
    l = a(f)
    w = list(f)
    for i in range(l):
        w[i] = chr(ord(w[i]) ^ ord(w[((i + 4) % l)])) #  这里和easyAsm不同，把加密后的立刻赋值到第一位
    else:
        return c(w)


def main():
    s = input('Guess?\n>> ')
    o = b'\xd2\xa8\xba\xa2\x92\xe6\x9b\xe3\xc8\xb3\xeb\xbb\xf3\xd5\xc3\xd8\x83\xda\xbd\x9d\x91\xaf\x89\xfe\x92'
    if e(s) == o:
        print('Correct!')
    else:
        print('Wrong...')


if __name__ == '__main__':
    main()

这题和easyAsm好像，我一直在找哪不同…（找了好久）

Exp脚本

enflag = b'\xd2\xa8\xba\xa2\x92\xe6\x9b\xe3\xc8\xb3\xeb\xbb\xf3\xd5\xc3\xd8\x83\xda\xbd\x9d\x91\xaf\x89\xfe\x92'
key = []
flag = [84,83,67,84,70,45,74,123,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,125]
l = len(enflag)

for i in range(l):
    key.append(enflag[l-i-1] - 128)

# 只加了这个for，其他都没变
for i in range(4):
    flag[i] ^= flag[i+4]  # 因为是加密后直接复制给原字串，所以要先加密一次，不然反推会错

for i in range(l):
    k = ((l-i-1)+4)%l
    flag[l-i-1] = key[l-i-1]^flag[k]

test_flag = []
for i in range(l):
    test_flag.append(chr(flag[i]))
    print(chr(flag[i]),end="")

得到flag: TSCTF-J{W0w!Th4t’S_Go0D!}

whoami

附件是图片，binwalk -e解出文件，运行里面的js代码，出现TtSC_T4F-Jf{e1NSc_e?T?h?A}
栅栏加密，取每组字数15

得到flag: TSCTF-J{1SThAt4__feNce???}

总结

感觉re都不太难，但自己明显对很多原理上的东西还没理解透彻，有时间希望能多看看书