2021 長安「戰疫」網路安全衛士守護賽 WriteUp

麻薯星的zyz想要生猴子!!!麻薯星的zyz想要生猴子!!!麻薯星的zyz想要生猴子!!!
隊友第一輪做了倆Web之後就擺爛了 寄
總體來說長安戰疫基本大部分題都偏向入門，適合大一新生練練手
少部分多百度也能做。
還有很小部分就看積累吧。

Misc

八卦迷宮

按照迷宮走然後取字的拼音即可

字是戰長恙長戰恙河長山山安戰疫疫戰疫安疫長安恙

flag是：

cazy{zhanchangyangchangzhanyanghechangshanshananzhanyiyizhanyianyichanganyang}

樸實無華的取證

首先檢視版本 imageinfo得到WinXPSP2x86

然後pslist，注意到

於是：

發現目錄是桌面而並非Desktop，重新filescan一下，匯出有用資訊

首先zip的密碼是上面說的20211209

其次，得到的txt是加密函數，而密文在flag.png上。反過來寫一個指令碼

但是我寫了幾次都沒寫對

。。。。於是有了這個指令碼

s = 'fdcb[8ldq?zloo?fhuwdlqob?vxffhhg?lq?iljkwlqj?wkh?hslghplf]'
for i in s:
    if(ord(i)>=ord('a') and ord(i)<=ord('w')):
        print(chr(ord(i)-3),end='')
    elif(i == 'a'):
        print('x',end='')
    elif(i == 'b'):
        print('y',end='')
    elif(i == 'c'):
        print('z',end='')
    elif(i == "|"):
        print('_')
    else:
        print(chr(ord(i)+32),end='')
 #ca`_{Xian_šill_certainl__s˜cceed_in_fighting_the_epidemic}

查了一下certainl後面應該還有個y

然後前面那個單詞是will，後面那個單詞是succeed，於是得到flag提交正確

cazy{Xian_will_certainly_succeed_in_fighting_the_epidemic}

無字天書

匯出HTTP流，在匯出的其中兩個檔案發現hex串，都是很明顯的zip，hex–>ascii，得到zip，開啟zip得到兩檔案，一個key.ws一個flag.txt

ws很明顯的whitespace，直接https://vii5ard.github.io/whitespace/得到key:XiAnWillBeSafe

然後flag.txt很明顯的SNOW

.\SNOW.EXE -p XiAnWillBeSafe -C .\flag.txt

cazy{C4n_y0u_underSt4nd_th3_b0oK_With0ut_Str1ng}

西安加油

檢視流量包發現大量的base64串，匯出http發現secret.txt，base64解碼發現是zip，儲存後開啟發現是拼圖

因為不知道大小，所以猜了一個12*4

命令montage *png -tile 12x4 -geometry 100x100+0+0 out2.png

然後用gaps

python3 gaps --image=out2.png --generations=10 --population=48 --size=100 --save
我gaps有問題，代數太多跑一會就報錯，不加save跑完就直接報錯。。。

得到flag，X的大小寫記不住了

cazy{make_XiAN_great_Again}

binary

檔案頭能看出來是class檔案，直接扔jadx

陣列轉出來

s = [77, 68, 65, 119, 77, 68, 65, 119, 77, 68, 69, 119, 77, 84, 69, 120, 77, 68, 65, 119, 77, 68, 65, 119, 77, 68, 65, 120, 77, 84, 69, 120, 77, 84, 69, 119, 77, 84, 69, 120, 77, 68, 65, 119, 77, 68, 65, 119, 77, 70, 120, 117, 77, 68, 69, 120, 77, 84, 69, 120, 77, 68, 69, 119, 77, 84, 69, 119, 77, 84, 65, 120, 77, 68, 69, 120, 77, 84, 69, 120, 77, 68, 65, 119, 77, 84, 69, 120, 77, 68, 69, 120, 77, 68, 69, 120, 77, 84, 69, 120, 77, 70, 120, 117, 77, 68, 69, 119, 77, 68, 65, 120, 77, 68, 69, 119, 77, 68, 65, 119, 77, 84, 69, 120, 77, 84, 65, 119, 77, 68, 69, 120, 77, 84, 65, 120, 77, 68, 69, 120, 77, 68, 69, 120, 77, 68, 69, 119, 77, 68, 65, 120, 77, 70, 120, 117, 77, 68, 69, 119, 77, 68, 65, 120, 77, 68, 69, 120, 77, 68, 65, 119, 77, 68, 65, 120, 77, 84, 65, 119, 77, 68, 69, 120, 77, 84, 65, 119, 77, 68, 65, 119, 77, 84, 65, 120, 77, 68, 69, 119, 77, 68, 65, 120, 77, 70, 120, 117, 77, 68, 69, 119, 77, 68, 65, 120, 77, 68, 69, 120, 77, 84, 65, 120, 77, 84, 65, 120, 77, 84, 65, 119, 77, 84, 69, 119, 77, 84, 69, 119, 77, 84, 65, 120, 77, 84, 69, 120, 77, 68, 69, 119, 77, 68, 65, 120, 77, 70, 120, 117, 77, 68, 69, 120, 77, 84, 69, 120, 77, 68, 69, 119, 77, 84, 69, 120, 77, 68, 69, 119, 77, 68, 65, 119, 77, 68, 65, 119, 77, 84, 65, 119, 77, 84, 65, 119, 77, 68, 65, 120, 77, 68, 69, 120, 77, 84, 69, 120, 77, 70, 120, 117, 77, 68, 65, 119, 77, 68, 65, 119, 77, 68, 69, 119, 77, 84, 65, 120, 77, 68, 69, 119, 77, 84, 65, 120, 77, 68, 69, 119, 77, 84, 65, 120, 77, 68, 69, 119, 77, 84, 65, 120, 77, 68, 65, 119, 77, 68, 65, 119, 77, 70, 120, 117, 77, 84, 69, 120, 77, 84, 69, 120, 77, 84, 69, 119, 77, 68, 69, 119, 77, 68, 65, 119, 77, 68, 65, 119, 77, 68, 69, 119, 77, 68, 69, 120, 77, 68, 65, 120, 77, 84, 69, 120, 77, 84, 69, 120, 77, 84, 69, 120, 77, 86, 120, 117, 77, 84, 69, 119, 77, 68, 65, 120, 77, 68, 69, 119, 77, 84, 65, 120, 77, 68, 65, 119, 77, 68, 69, 119, 77, 84, 69, 120, 77, 84, 69, 120, 77, 68, 69, 119, 77, 68, 65, 119, 77, 68, 65, 120, 77, 84, 65, 119, 77, 70, 120, 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84, 65, 120, 77, 84, 69, 119, 77, 84, 65, 120, 77, 84, 69, 119, 77, 84, 69, 120, 77, 84, 69, 119, 77, 86, 120, 117, 77, 68, 65, 120, 77, 68, 69, 119, 77, 68, 69, 119, 77, 68, 69, 120, 77, 84, 69, 120, 77, 84, 69, 119, 77, 84, 69, 120, 77, 68, 65, 119, 77, 68, 69, 120, 77, 68, 65, 120, 77, 68, 69, 119, 77, 68, 65, 120, 77, 70, 120, 117, 77, 68, 65, 120, 77, 68, 65, 119, 77, 84, 69, 119, 77, 84, 69, 120, 77, 68, 69, 120, 77, 68, 69, 120, 77, 68, 65, 120, 77, 84, 65, 119, 77, 84, 69, 119, 77, 68, 69, 120, 77, 68, 65, 120, 77, 84, 69, 119, 77, 86, 120, 117, 77, 84, 69, 120, 77, 68, 69, 119, 77, 68, 69, 120, 77, 68, 65, 119, 77, 84, 69, 120, 77, 84, 69, 120, 77, 84, 65, 120, 77, 84, 65, 120, 77, 68, 65, 120, 77, 84, 65, 119, 77, 68, 65, 119, 77, 68, 65, 120, 77, 70, 120, 117, 77, 68, 65, 119, 77, 68, 69, 120, 77, 84, 65, 120, 77, 68, 69, 119, 77, 68, 65, 120, 77, 84, 69, 119, 77, 68, 65, 119, 77, 68, 69, 119, 77, 84, 69, 119, 77, 84, 69, 120, 77, 84, 69, 120, 77, 68, 69, 120, 77, 86, 120, 117, 77, 84, 69, 119, 77, 84, 69, 119, 77, 68, 69, 120, 77, 68, 69, 119, 77, 84, 69, 119, 77, 84, 65, 119, 77, 84, 69, 119, 77, 68, 65, 120, 77, 68, 69, 119, 77, 68, 69, 120, 77, 68, 65, 119, 77, 68, 69, 119, 77, 70, 120, 117, 77, 68, 69, 119, 77, 84, 65, 119, 77, 84, 65, 119, 77, 84, 69, 120, 77, 84, 65, 119, 77, 84, 65, 119, 77, 68, 65, 119, 77, 84, 65, 119, 77, 84, 69, 120, 77, 68, 65, 120, 77, 68, 65, 120, 77, 68, 69, 120, 77, 86, 120, 117, 77, 68, 69, 119, 77, 84, 65, 120, 77, 68, 65, 120, 77, 84, 65, 119, 77, 68, 69, 120, 77, 84, 65, 119, 77, 68, 69, 120, 77, 68, 65, 120, 77, 68, 65, 119, 77, 68, 65, 120, 77, 68, 69, 119, 77, 84, 65, 119, 77, 70, 120, 117, 77, 84, 65, 119, 77, 84, 69, 119, 77, 84, 69, 120, 77, 84, 69, 119, 77, 84, 69, 120, 77, 68, 69, 120, 77, 68, 65, 120, 77, 68, 65, 120, 77, 84, 69, 120, 77, 84, 69, 119, 77, 84, 65, 120, 77, 84, 69, 119, 77, 86, 120, 117, 77, 84, 69, 119, 77, 84, 69, 119, 77, 68, 65, 120, 77, 68, 69, 120, 77, 84, 65, 119, 77, 68, 65, 119, 77, 68, 69, 119, 77, 84, 69, 120, 77, 68, 69, 120, 77, 68, 65, 119, 77, 84, 65, 120, 77, 84, 65, 120, 77, 70, 120, 117, 77, 68, 65, 120, 77, 84, 65, 119, 77, 84, 65, 119, 77, 68, 69, 120, 77, 84, 69, 119, 77, 84, 69, 119, 77, 68, 65, 120, 77, 84, 69, 120, 77, 68, 69, 119, 77, 68, 69, 119, 77, 68, 69, 120, 77, 84, 69, 119, 77, 86, 120, 117, 77, 68, 69, 119, 77, 84, 65, 119, 77, 68, 65, 119, 77, 84, 69, 120, 77, 68, 69, 119, 77, 84, 69, 120, 77, 68, 69, 120, 77, 68, 69, 119, 77, 84, 69, 120, 77, 84, 69, 120, 77, 68, 69, 119, 77, 68, 65, 120, 77, 70, 120, 117, 77, 68, 69, 119, 77, 84, 65, 120, 77, 84, 65, 120, 77, 84, 65, 119, 77, 84, 65, 119, 77, 84, 65, 119, 77, 68, 65, 119, 77, 68, 69, 120, 77, 68, 69, 119, 77, 68, 65, 120, 77, 68, 65, 120, 77, 84, 69, 120, 77, 86, 120, 117, 77, 68, 69, 120, 77, 68, 69, 119, 77, 68, 65, 120, 77, 68, 65, 119, 77, 84, 69, 120, 77, 68, 65, 120, 77, 68, 69, 120, 77, 68, 65, 120, 77, 84, 65, 120, 77, 84, 69, 120, 77, 84, 65, 119, 77, 84, 69, 119, 77, 70, 120, 117, 77, 68, 69, 120, 77, 84, 65, 119, 77, 84, 69, 120, 77, 84, 69, 119, 77, 68, 65, 119, 77, 68, 65, 120, 77, 68, 69, 120, 77, 68, 69, 120, 77, 68, 69, 120, 77, 84, 65, 119, 77, 84, 69, 120, 77, 84, 69, 119, 77, 70, 120, 117, 77, 68, 69, 119, 77, 68, 69, 120, 77, 68, 65, 120, 77, 68, 69, 120, 77, 68, 65, 120, 77, 68, 69, 119, 77, 68, 65, 120, 77, 68, 69, 120, 77, 84, 65, 120, 77, 84, 65, 119, 77, 68, 65, 119, 77, 68, 65, 119, 77, 70, 120, 117, 77, 84, 69, 120, 77, 84, 69, 120, 77, 84, 69, 119, 77, 84, 65, 120, 77, 84, 65, 119, 77, 84, 69, 120, 77, 68, 65, 120, 77, 84, 69, 119, 77, 68, 69, 119, 77, 84, 65, 120, 77, 84, 69, 119, 77, 84, 65, 120, 77, 86, 120, 117, 77, 68, 65, 119, 77, 68, 65, 119, 77, 68, 69, 120, 77, 84, 65, 119, 77, 68, 69, 120, 77, 84, 65, 120, 77, 84, 65, 120, 77, 68, 69, 120, 77, 68, 65, 119, 77, 84, 65, 120, 77, 68, 69, 119, 77, 68, 69, 119, 77, 70, 120, 117, 77, 68, 69, 120, 77, 84, 69, 120, 77, 68, 69, 120, 77, 84, 65, 119, 77, 84, 69, 119, 77, 84, 65, 120, 77, 68, 69, 120, 77, 68, 69, 119, 77, 84, 69, 119, 77, 68, 65, 120, 77, 84, 69, 119, 77, 84, 69, 120, 77, 86, 120, 117, 77, 68, 69, 119, 77, 68, 65, 120, 77, 68, 69, 119, 77, 68, 69, 120, 77, 68, 65, 119, 77, 68, 69, 120, 77, 68, 65, 120, 77, 84, 65, 120, 77, 68, 65, 119, 77, 68, 65, 119, 77, 68, 65, 119, 77, 68, 65, 120, 77, 70, 120, 117, 77, 68, 69, 119, 77, 68, 65, 120, 77, 68, 69, 119, 77, 84, 69, 120, 77, 84, 69, 119, 77, 84, 69, 119, 77, 68, 65, 120, 77, 84, 69, 120, 77, 84, 69, 120, 77, 84, 69, 120, 77, 68, 69, 119, 77, 68, 69, 120, 77, 86, 120, 117, 77, 68, 69, 119, 77, 68, 65, 120, 77, 68, 69, 119, 77, 84, 69, 119, 77, 84, 69, 120, 77, 84, 69, 120, 77, 84, 69, 119, 77, 68, 65, 119, 77, 68, 65, 120, 77, 68, 69, 119, 77, 84, 65, 120, 77, 68, 69, 120, 77, 70, 120, 117, 77, 68, 69, 120, 77, 84, 69, 120, 77, 68, 69, 120, 77, 84, 69, 120, 77, 84, 65, 119, 77, 68, 69, 119, 77, 84, 69, 119, 77, 84, 65, 119, 77, 84, 69, 120, 77, 84, 65, 119, 77, 68, 69, 120, 77, 68, 69, 120, 77, 70, 120, 117, 77, 68, 65, 119, 77, 68, 65, 119, 77, 68, 69, 120, 77, 84, 69, 120, 77, 84, 65, 120, 77, 84, 69, 120, 77, 68, 69, 120, 77, 68, 65, 119, 77, 68, 65, 119, 77, 68, 69, 119, 77, 68, 65, 120, 77, 84, 65, 119, 77, 65, 61, 61]
for i in s:
    print(chr(i),end='')

得到base64，解碼是01串，明顯的二維條碼

s = '0000000101110000000011111101110000000\n0111110101101010111110001110110111110\n0100010100001111000111010110110100010\n0100010110000011000111000001010100010\n0100010111011011001101101011110100010\n0111110101110100000001001000010111110\n0000000101010101010101010101010000000\n1111111100100000000100110011111111111\n1100010101010000101111110100000011000\n0101101000110010010000100110101011101\n1011000001001111001100011010000010010\n1110111111110010101101000110101011100\n1010110001110000000110100000000000010\n0110101001000100011011101011101111101\n0010100100111111101110000110010100010\n0010001101110110110011001100110011101\n1110100110001111111011010011000000010\n0000111010100011100000101101111110111\n1101100110101101001100010100110000100\n0101001001111001000001001110010010111\n0101010011000111000110010000010101000\n1001101111101110110010011111101011101\n1101100010111000000101110110001011010\n0011001000111101100011110100100111101\n0101000001110101110110101111110100010\n0101011011001001000000110100010011111\n0110100010001110010110011011111001100\n0111001111100000010110110111001111100\n0100110010110010100010111011000000000\n1111111101011001110011100101011101011\n0000000111000111011010110001010100100\n0111110111001101010110101100011101111\n0100010100110000110011010000000000010\n0100010101111101100011111111110100111\n0100010101101111111100000010101010110\n0111110111111000101101001111000110110\n0000000111111011110110000000100011000'
s = s.split('\n')

from PIL import Image
pic = Image.new('RGB',(37,37),(255,255,255))
for i in range(37):
    for j in range(37):
        if(s[i][j] == '0'):
            pic.putpixel((j,i),(0,0,0))
pic.show()
pic.save('fllllag.png')

掃碼得到flag

flag{932b2c0070e4897ea7df0190dbf36ece}

Ez_Steg

pyc的steg很明顯是劍龍，注意python版本號，我用3.9沒跑出來，3.6能跑

跑出來得到key：St3g1sV3ryFuNny

當然密文更明顯是emoji-aes，解密得到flag

cazy{Em0j1s_AES_4nd_PyC_St3g_D0_yoU_l1ke}

ez_Encrypt

這次題目的流量包都只需要匯出HTTP就能做了

匯出之後有個web123，是base64，同樣cyberchef解碼得到zip檔案，用D盾掃

百度找一個解php混淆的，除去廣告第一個就是https://www.zhaoyuanma.com/phpjm.html

解密得到flag

cazy{PHP_ji4m1_1s_s00000_3aSyyyyyyyyyyy}

Crypto

no_cry_no_can

就單純的互斥或，通過格式cazy{找出key的值

key = b'\x5f\x11\x32\xff\x61'
s = b'<pH\x86\x1a&"m\xce\x12\x00pm\x97U1uA\xcf\x0c:NP\xcf\x18~l'
for i in range(len(s)):
    print(chr(key[i%5]^s[i]),end='')

cazy{y3_1s_a_h4nds0me_b0y!}

no_can_no_bb

單純的爆破key,給了key的範圍是1,1<<20，還好簡單，要不然就不會做了

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

def pad(m):
    tmp = 16-(len(m)%16)
    return m + bytes([tmp for _ in range(tmp)])

enc=b'\x9d\x18K\x84n\xb8b|\x18\xad4\xc6\xfc\xec\xfe\x14\x0b_T\xe3\x1b\x03Q\x96e\x9e\xb8MQ\xd5\xc3\x1c'
for i in tqdm(range(1<<20)):
    key=pad(long_to_bytes(i))
    aes=AES.new(key,AES.MODE_ECB)
    s = aes.decrypt(enc)
    if b'cazy{' in s:
        print(s)

no_math_no_cry

真就太久沒學數學唄，還有負根，一開始都忘乾淨了，果然我不適合做cry，但還好這三道和密碼學關係不是特別的大。

from Crypto.Util.number import*

import gmpy2
s = 10715086071862673209484250490600018105614048117055336074437503883703510511248211671489145400471130049712947188505612184220711949974689275316345656079538583389095869818942817127245278601695124271626668045250476877726638182396614587807925457735428719972874944279172128411500209111406507112585996098530169
s -= 0x0338470
s = gmpy2.iroot(s,2)[0]
s = -s
s += (1<<500)
print(long_to_bytes(s))

cazy{1234567890_no_m4th_n0_cRy}

Reverse

combat_slogan

jdgui開啟看main就看見加密的flag了，上面函數明顯的rot13

線上rot13解一下就行了，然後套上flag{}

flag{We_w11l_f1ght_t0_end_t0_end_cazy}

cute_doge

IDA開啟ctf1.exe，搜字串，看見ZmxhZ3tDaDFuYV95eWRzX2Nhenl9

base64解碼就是flag

flag{Ch1na_yyds_cazy}

hello_py

uncompyle6 easy_py.cpython-38.pyc > easy_py.py

出來一個py檔案，看了下，首先進encrypt1進行互斥或，再進入encrypt2進行互斥或，然後輸出和Happy進行比較

既然是這樣，那不妨反過來，把num從9到0改成從0到9，把該減的地方改成加，該執行的順序也換一下。

# uncompyle6 version 3.7.4
# Python bytecode 3.8 (3413)
# Decompiled from: Python 3.8.7 (default, Dec 22 2020, 10:37:26) 
# [GCC 10.2.1 20201207]
# Embedded file name: C:\Users\Administrator\Desktop\easy_py.py
# Compiled at: 2021-12-28 15:45:17
# Size of source mod 2**32: 1099 bytes
import threading, time

def encode_1(n):
    global num
    while True:
        if num <= 9:
            flag[num] = flag[num] ^ num
            num += 1
            time.sleep(0.1)
        if num > 9:
            break


def encode_2(n):
    global num
    while True:
        if num <= 9:
            flag[num] = flag[num] ^ flag[(num + 1)]
            num += 1
            time.sleep(0.1)
        if num > 9:
            break


while True:
    Happy = [
     44, 100, 3, 50, 106, 90, 5, 102, 10, 112]
    num = 0
    f = input('Please input your flag:')
    if len(f) == 10:
        print('Your input is illegal')
    else:
        flag = [44, 100, 3, 50, 106, 90, 5, 102, 10, 112]
        if(1 == 2):
            print('crazymumuzi!')
        else:
            print("flag to 'ord':", flag)
            t1 = threading.Thread(target=encode_1, args=(1, ))
            t2 = threading.Thread(target=encode_2, args=(2,))
            t2.start()
            t1.start()
            t1.join()
            t2.join()


        for i in flag:
            print(chr(i),end='')
        if flag == Happy:
            print('Good job!')
        else:
            print('No no no!')
# okay decompiling easy_py.cpython-38.pyc

得到flag,包上flag{}即可

flag{He110_cazy}