def decompress(self, dump_dir):
# Check if the file type is right.
# TODO: this might be a bit hacky, need to verify whether malformed
# Flash exploit would get a different file type.
if 'Flash' not in __sessions__.current.file.type:
self.log('error', "The opened file doesn't appear to be a valid SWF object")
return
# Retrieve key information from the opened SWF file.
header, version, size, data = self.parse_swf()
# Decompressed data.
decompressed = None
# Check if the file is already a decompressed Flash object.
if header == 'FWS':
self.log('info', "The opened file doesn't appear to be compressed")
return
# Check if the file is compressed with zlib.
elif header == 'CWS':
self.log('info', "The opened file appears to be compressed with Zlib")
# Open an handle on the compressed data.
compressed = StringIO(data)
# Skip the header.
compressed.read(3)
# Decompress and reconstruct the Flash object.
decompressed = 'FWS' + compressed.read(5) + zlib.decompress(compressed.read())
# Check if the file is compressed with lzma.
elif header == 'ZWS':
self.log('info', "The opened file appears to be compressed with Lzma")
# We need an third party library to decompress this.
if not HAVE_PYLZMA:
self.log('error', "Missing dependency, please install pylzma (`pip install pylzma`)")
return
# Open and handle on the compressed data.
compressed = StringIO(data)
# Skip the header.
compressed.read(3)
# Decompress with pylzma and reconstruct the Flash object.
## ZWS(LZMA)
## | 4 bytes | 4 bytes | 4 bytes | 5 bytes | n bytes | 6 bytes |
## | 'ZWS'+version | scriptLen | compressedLen | LZMA props | LZMA data | LZMA end marker |
decompressed = 'FWS' + compressed.read(5)
compressed.read(4) # skip compressedLen
decompressed += pylzma.decompress(compressed.read())
# If we obtained some decompressed data, we print it and eventually
# dump it to file.
if decompressed:
# Print the decompressed data
# TODO: this prints too much, need to find a better wayto display
# this. Paginate?
self.log('', cyan(hexdump(decompressed)))
if dump_dir:
# Dump the decompressed SWF file to the specified directory
# or to the default temporary one.
dump_path = os.path.join(dump_dir, '{0}.swf'.format(get_md5(decompressed)))
with open(dump_path, 'wb') as handle:
handle.write(decompressed)
self.log('info', "Flash object dumped at {0}".format(dump_path))
# Directly open a session on the dumped Flash object.
__sessions__.new(dump_path)
def decompress(self, dump_dir):
# Check if the file type is right.
# TODO: this might be a bit hacky, need to verify whether malformed
# Flash exploit would get a different file type.
if 'Flash' not in __sessions__.current.file.type:
self.log(
'error',
"The opened file doesn't appear to be a valid SWF object")
return
# Retrieve key information from the opened SWF file.
header, version, size, data = self.parse_swf()
# Decompressed data.
decompressed = None
# Check if the file is already a decompressed Flash object.
if header == 'FWS':
self.log('info', "The opened file doesn't appear to be compressed")
return
# Check if the file is compressed with zlib.
elif header == 'CWS':
self.log('info',
"The opened file appears to be compressed with Zlib")
# Open an handle on the compressed data.
compressed = StringIO(data)
# Skip the header.
compressed.read(3)
# Decompress and reconstruct the Flash object.
decompressed = 'FWS' + compressed.read(5) + zlib.decompress(
compressed.read())
# Check if the file is compressed with lzma.
elif header == 'ZWS':
self.log('info',
"The opened file appears to be compressed with Lzma")
# We need an third party library to decompress this.
if not HAVE_PYLZMA:
self.log(
'error',
"Missing dependency, please install pylzma (`pip install pylzma`)"
)
return
# Open and handle on the compressed data.
compressed = StringIO(data)
# Skip the header.
compressed.read(3)
# Decompress with pylzma and reconstruct the Flash object.
## ZWS(LZMA)
## | 4 bytes | 4 bytes | 4 bytes | 5 bytes | n bytes | 6 bytes |
## | 'ZWS'+version | scriptLen | compressedLen | LZMA props | LZMA data | LZMA end marker |
decompressed = 'FWS' + compressed.read(5)
compressed.read(4) # skip compressedLen
decompressed += pylzma.decompress(compressed.read())
# If we obtained some decompressed data, we print it and eventually
# dump it to file.
if decompressed:
# Print the decompressed data
# TODO: this prints too much, need to find a better wayto display
# this. Paginate?
self.log('', cyan(hexdump(decompressed)))
if dump_dir:
# Dump the decompressed SWF file to the specified directory
# or to the default temporary one.
dump_path = os.path.join(
dump_dir, '{0}.swf'.format(get_md5(decompressed)))
with open(dump_path, 'wb') as handle:
handle.write(decompressed)
self.log('info',
"Flash object dumped at {0}".format(dump_path))
# Directly open a session on the dumped Flash object.
__sessions__.new(dump_path)
def run(self):
super(Shellcode, self).run()
if self.args is None:
return
if not __sessions__.is_set():
self.log('error', "No session opened")
return
collection = [
{
'description': 'FS:[30h] shellcode',
'patterns': [
b'\x64\xa1\x30\x00|\x64\x8b\x0d\x30|\x64\x8b\x0d\x30|\x64\x8b\x15\x30|\x64\x8b\x35\x30|\x64\x8b\x3d\x30|\x6a\x30.\x64\x8b|\x33..\xb3\x64\x8b',
'64a13000|648b0d30|648b0d30|648b1530|648b3530|648b3d30|6a30..648b|33....b3648b'
]
},
{
'description': 'FS:[00h] shellcode',
'patterns': [
b'\x64\x8b\x1d|\x64\xa1\x00|\x64\x8b\x0d|\x64\x8b\x15|\x64\x8b\x35|\x64\x8b\x3d',
'648b1d00|64a10000|648b0d00|648b1500|648b3500|648b3d00'
]
},
{
'description': 'API hashing',
'patterns': [
b'\x74.\xc1.\x0d\x03|\x74.\xc1.\x07\x03',
'74..c1..0d03|74..c1..0703'
]
},
{
'description': 'PUSH DWORD[]/CALL[]',
'patterns': [
b'\x00\xff\x75\x00\xff\x55',
'00ff7500ff55'
]
},
{
'description': 'FLDZ/FSTENV [esp-12]',
'patterns': [
b'\x00\xd9\x00\xee\x00\xd9\x74\x24\x00\xf4\x00\x00',
'00d900ee00d9742400f40000'
]
},
{
'description': 'CALL next/POP',
'patterns': [
b'\x00\xe8\x00\x00\x00\x00(\x58|\x59|\x5a|\x5b|\x5e|\x5f|\x5d)\x00\x00',
'00e800000000(58|59|5a|5b|5e|5f|5d)0000'
]
},
{
'description': 'Function prolog',
'patterns': [
b'\x55\x8b\x00\xec\x83\x00\xc4|\x55\x8b\x0ec\x81\x00\xec|\x55\x8b\x00\xec\x8b|\x55\x8b\x00\xec\xe8|\x55\x8b\x00\xec\xe9',
'558b00ec8300c4|558b0ec8100ec|558b00ec8b|558b00ece8|558b00ece9'
]
},
]
self.log('info', "Searching for known shellcode patterns...")
for entry in collection:
for pattern in entry['patterns']:
match = re.search(pattern, __sessions__.current.file.data)
if match:
offset = match.start()
self.log('info', "{0} pattern matched at offset {1}".format(entry['description'], offset))
self.log('', cyan(hexdump(__sessions__.current.file.data[offset:], maxlines=15)))
