# GynvaelEN mission 007

# cat parser.py
#        00000000  50 4b 03 04 14 00 00 00  00 00 fc 96 dc 4a 73 03  |PK...........Js.|
#        00000010  1a 7b 5e 00 00 00 7a 00  00 00 0a 00 00 00 72 65  |.{^...z.......re|
#        00000020  70 6f 72 74 2e 74 78 74  f8 07 54 16 3b 8b 63 cc  |port.txt..T.;.c.|
#        00000030  78 b7 03 42 4c 35 b8 0f  72 43 87 8f ab a8 55 3b  |x..BL5..rC....U;|
#        00000040  7f ee 9b 48 88 1a 2b cb  f3 52 73 bf 6f e2 11 37  |...H..+..Rs.o..7|
#        00000050  f2 06 a9 d3 53 12 2b d1  fe ff 47 34 58 be be 03  |....S.+...G4X...|
#        00000060  7f cb 15 08 b2 5a 58 2e  3a 51 61 1c b2 db 63 b6  |.....ZX.:Qa...c.|
#        00000070  5e 3a 76 98 0b 9a 32 12  88 cb b2 8c d3 d6 d4 fa  |^:v...2.........|
#        00000080  b7 37 b5 27 00 00 50 4b  01 02 14 00 14 00 00 00  |.7.'..PK........|
#        00000090  00 00 fc 96 dc 4a 73 03  1a 7b 5e 00 00 00 7a 00  |.....Js..{^...z.|
#        000000a0  00 00 0a 00 24 00 00 00  00 00 01 00 20 00 00 00  |....$....... ...|
#        000000b0  00 00 00 00 72 65 70 6f  72 74 2e 74 78 74 0a 00  |....report.txt..|
#        000000c0  20 00 00 00 00 00 01 00  18 00 00 6e 5c 69 2f f0  | ..........n\i/.|
#        000000d0  d2 01 00 6e 5c 69 2f f0  d2 01 80 d0 e0 52 2f f0  |...n\i/......R/.|
#        000000e0  d2 01 50 4b 05 06 00 00  00 00 01 00 01 00 5c 00  |..PK..........\.|
#        000000f0  00 00 86 00 00 00 00 00                           |........|
#        000000f8

import struct
import sys

def extract_bytes(offset, num, ctype = None):
    j = offset
    k = j + num
    if ctype:
        return struct.unpack(ctype, data[j:k])[0]
    else:
        return repr(data[j:k])

with open(sys.argv[1]) as f:
    data = f.read()

ep = 0
print 'Local file header signature', extract_bytes(ep + 0, 4)
print 'Version needed to extract', extract_bytes(ep + 4, 2)
print 'General purpose bit flag', extract_bytes(ep + 6, 2)
print 'Compression method', extract_bytes(ep + 8, 2)
print 'File last modification time', extract_bytes(ep + 10, 2)
print 'File last modification date', extract_bytes(ep + 12, 2)
print 'CRC-32', extract_bytes(ep + 14, 4)
cs = extract_bytes(ep + 18, 4, '<I')
print 'Compressed size', cs
print 'Uncompressed size', extract_bytes(ep + 22, 4)
n = extract_bytes(ep + 26, 2, '<H')
print 'File name length (n)', n
m = extract_bytes(ep + 28, 2, '<H')
print 'Extra field length (m)', m
print 'File name', extract_bytes(ep + 30, n)
print 'Extra field', extract_bytes(ep + 30 + n, m)
print '--------'
epcdfhs = data.index('PK\x01\x02')
i = ep + 30 + n
j = epcdfhs - cs - i
print 'Extra field', extract_bytes(i, j)
print 'Compressed data', extract_bytes(i + j, cs)
print '--------'
ep = epcdfhs
print 'Central directory file header signature', extract_bytes(ep + 0, 4)
print 'Version made by', extract_bytes(ep + 4, 2)
print 'Version needed to extract', extract_bytes(ep + 6, 2)
print 'General purpose bit flag', extract_bytes(ep + 8, 2)
print 'Compression method', extract_bytes(ep + 10, 2)
print 'File last modification time', extract_bytes(ep + 12, 2)
print 'File last modification date', extract_bytes(ep + 14, 2)
print 'CRC-32', extract_bytes(ep + 16, 4)
print 'Compressed size', extract_bytes(ep + 20, 4)
print 'Uncompressed size', extract_bytes(ep + 24, 4)
n = extract_bytes(ep + 28, 2, '<H')
print 'File name length (n)', n
m = extract_bytes(ep + 30, 2, '<H')
print 'Extra field length (m)', m
k = extract_bytes(ep + 32, 2, '<H')
print 'File comment length (k)', k
print 'Disk number where file starts', extract_bytes(ep + 34, 2)
print 'Internal file attributes', extract_bytes(ep + 36, 2)
print 'External file attributes', extract_bytes(ep + 38, 4)
print 'Relative offset of local file header', extract_bytes(ep + 42, 4)
print 'File name', extract_bytes(ep + 46, n)
print 'Extra field', extract_bytes(ep + 46 + n, m)
print 'File comment', extract_bytes(ep + 46 + n + m, k)

# python parser.py report.zip
Local file header signature 'PK\x03\x04'
Version needed to extract '\x14\x00'
General purpose bit flag '\x00\x00'
Compression method '\x00\x00'
File last modification time '\xfc\x96'
File last modification date '\xdcJ'
CRC-32 's\x03\x1a{'
Compressed size 94
Uncompressed size 'z\x00\x00\x00'
File name length (n) 10
Extra field length (m) 0
File name 'report.txt'
Extra field ''
--------
Extra field ''
Compressed data "\xf8\x07T\x16;\x8bc\xccx\xb7\x03BL5\xb8\x0frC\x87\x8f\xab\xa8U;\x7f\xee\x9bH\x88\x1a+\xcb\xf3Rs\xbfo\xe2\x117\xf2\x06\xa9\xd3S\x12+\xd1\xfe\xffG4X\xbe\xbe\x03\x7f\xcb\x15\x08\xb2ZX.:Qa\x1c\xb2\xdbc\xb6^:v\x98\x0b\x9a2\x12\x88\xcb\xb2\x8c\xd3\xd6\xd4\xfa\xb77\xb5'\x00\x00"
--------
Central directory file header signature 'PK\x01\x02'
Version made by '\x14\x00'
Version needed to extract '\x14\x00'
General purpose bit flag '\x00\x00'
Compression method '\x00\x00'
File last modification time '\xfc\x96'
File last modification date '\xdcJ'
CRC-32 's\x03\x1a{'
Compressed size '^\x00\x00\x00'
Uncompressed size 'z\x00\x00\x00'
File name length (n) 10
Extra field length (m) 36
File comment length (k) 0
Disk number where file starts '\x00\x00'
Internal file attributes '\x01\x00'
External file attributes ' \x00\x00\x00'
Relative offset of local file header '\x00\x00\x00\x00'
File name 'report.txt'
Extra field '\n\x00 \x00\x00\x00\x00\x00\x01\x00\x18\x00\x00n\\i/\xf0\xd2\x01\x00n\\i/\xf0\xd2\x01\x80\xd0\xe0R/\xf0\xd2\x01'
File comment ''

# cat generate_zipfiles.py
from subprocess import Popen, PIPE
from sys import argv

cm = {  0: 'The file is stored (no compression)',
        1: 'The file is Shrunk',
        2: 'The file is Reduced with compression factor 1',
        3: 'The file is Reduced with compression factor 2',
        4: 'The file is Reduced with compression factor 3',
        5: 'The file is Reduced with compression factor 4',
        6: 'The file is Imploded',
        7: 'Reserved for Tokenizing compression algorithm',
        8: 'The file is Deflated',
        9: 'Enhanced Deflating using Deflate64(tm)',
        10: 'PKWARE Data Compression Library Imploding (old IBM TERSE)',
        11: 'Reserved by PKWARE',
        12: 'File is compressed using BZIP2 algorithm',
        13: 'Reserved by PKWARE',
        14: 'LZMA (EFS)',
        15: 'Reserved by PKWARE',
        16: 'Reserved by PKWARE',
        17: 'Reserved by PKWARE',
        18: 'File is compressed using IBM TERSE (new)',
        19: 'IBM LZ77 z Architecture (PFS)',
        97: 'WavPack compressed data',
        98: 'PPMd version I, Rev 1'
}

ofn = argv[1]
nfn = 'new'
rfn = 'report.txt'

with open(ofn) as f:
    data = f.read()

for i in range(256):
    data = data[:8] + chr(i) + data[9:144] + chr(i) + data[145:]
    with open(nfn, 'wb') as f:
        f.write(data)
    command = '7z x ' + nfn
    p = Popen(command.split(), stdout = PIPE, stderr = PIPE)
    o, e = p.communicate()
    if 'Everything is Ok' in o:
        print i, cm[i]
        command = 'cat ' + rfn
        p = Popen(command.split(), stdout = PIPE, stderr = PIPE)
        o, e  = p.communicate()
        print o
    command = 'rm ' + nfn + ' ' + rfn
    p = Popen(command.split(), stdout = PIPE, stderr = PIPE)
    p.communicate()

# python generate_zipfiles.py report.zip
98 PPMd version I, Rev 1
The secret password is:
  My name is Bond, James Bond.
Seriously, you could have guessed this based on the mission ID.

Source

https://www.youtube.com/watch?v=z9hfkajoAvc (1:25:15)

References

https://en.wikipedia.org/wiki/Zip_(file_format)
https://pkware.cachefly.net/webdocs/casestudies/APPNOTE.TXT (4.4.5)
https://github.com/corkami/pics/blob/master/binary/zip101/zip101.pdf