buuctf misc zip

zip

Extract a lot zip file , But the size is small , If you run a weak password, you can't run out

utilize crc Blast data, Then he can splice the data as described in the title

#python3
import zipfile
import string
import binascii

def CrackCrc(crc):
	for i in dic:
		for j in dic:
			for k in dic:
				for h in dic:
					s = i + j + k + h
					if crc == (binascii.crc32(s.encode())):
						f.write(s)
						return

def CrackZip():
	for i in range(0,68):
		file = 'out'+str(i)+'.zip'
		crc = zipfile.ZipFile(file,'r').getinfo('data.txt').CRC
		CrackCrc(crc)
		print('\r'+"loading：{:%}".format(float((i+1)/68)),end='')

dic = string.ascii_letters + string.digits + '+/='
f = open('out.txt','w')
print("\nCRC32begin")
CrackZip()
print("CRC32finished")
f.close()

After blasting , It's strange to find the data , Comparing the tail features, it is found that the head is missing rar file

A filling rar The file header , Decompression is obtained. flag

what flag It's not in there

see rar Compressed package comments , have to flag

rar v 1.rar

flag{nev3r_enc0de_t00_sm4ll_fil3_w1th_zip}