''' 
KeyBoy Config file decoder
From: It's Parliamentary: KeyBoy and the targeting of the Tibetan Community
Permalink: https://citizenlab.org/2016/11/parliament-keyboy/

Adam Hulcoop / September 19, 2016
adam.hulcoop[@]citizenlab.ca
'''
import sys
import argparse
import logging

LookupTable = {}

# Function to compute 9-bit sliding window values and return list of converted indices
def byteDecoder(rawBytes):
	#rawBytes should be bytearray of values
	k=0
	ba = []

	bytex=0
	while( bytex < len(rawBytes) -1):

		index = 0
		ix = bytex
		t=0
		while ( index < 9):
			
			while (k<8):
				
				if( ( ord(rawBytes[ix]) & (1 << (7-k))) > 0  ):
					t = 2*t +1
				else:
					t = 2*t
				
				index+=1
				k+=1
				
				if( index > 8):
					break
				
				if ( k==8 ):
					ix+=1
					k=0
				
				
			if (index<=8):
				k=0
			elif ( (index == 9) and (k==8)):
				k=0
				bytex+=1
		#t should hold the resultant value
		ba.append(t)
		bytex+=1


	return ba




def CreateLookupTable():
	for x in xrange(0,256):
		LookupTable[x] = "{:x}".format(x)

	# 0x101 is used as the exit value
	LookupTable[257]  = "reserved"

	return



def BuildExtraLookupTable(curIndex, prevIndex):
	#curIndex and prevIndex are indices from the decoded input file
	startFrom = len(LookupTable)

	if( curIndex > startFrom) :
		# if we are looking up an index beyond the existing table size
		vPrev = LookupTable.get(prevIndex)
		vCur = LookupTable.get(prevIndex)
	else:
		vPrev = LookupTable.get(prevIndex)
		vCur = LookupTable.get(curIndex)
	
	newVal = vPrev


	if( len(vCur.split(',')) > 1 ):
		augItem = vCur.split(',')[0]
	else:
		augItem = vCur

	newVal = ','.join([vPrev,augItem])

	LookupTable[startFrom+1] = newVal
	logging.debug("0x%x => %s" % ((startFrom+1),newVal ))
	
	return

	
if __name__ == "__main__":
  
	parser = argparse.ArgumentParser(description='Decode KeyBoy backdoor configuration files')
	parser.add_argument('FILE', help='KeyBoy encoded config file')
	parser.add_argument('--verbose','-v',action='store_true',help='Enable verbose output')
	parser.add_argument('--skip','-s',type=int,help='Skip over <SKIP> bytes at beginning of file')
	args = parser.parse_args()

	if args.verbose:
		logging.basicConfig(format='%(message)s',level=logging.DEBUG)
	else:
		logging.basicConfig(format='%(message)s',level=logging.WARNING)


	print "============================"
	print "{KeyBoy Config file Decoder}"
	print "============================"
	print ""

	with open(args.FILE, "rb") as f:

		if args.skip is None:
			f.seek(0,0)
		else:
			logging.warn("Skipping %i bytes.." % args.skip)
			f.seek(args.skip,0)

		szfile = f.read(8)
		szf_dat = int(szfile,16)
		logging.debug("Size of decoded config file:\t%i bytes" % szf_dat)

		szconf = f.read(8)
		szc_dat = int(szconf,16)
		logging.debug("Size of encoded config data:\t%i bytes" % szc_dat)
		logging.debug("")

		bytesRaw = f.read(szc_dat)
		ba = byteDecoder(bytesRaw)

	#create the initial Lookup table
	CreateLookupTable()

	ResultsList = []

	#Build the extra lookup table values
	logging.debug("Dynamic lookup table entries:")
	for val in range(len(ba)):

		#for each entry in the bytes array,
		# we need to look up the value in the table.
		# As we go, we need to build new entries on the table
		# corresponding to the value from this lookup, concatenated with the first character from the
		# the value printed in the previous lookup. BuildExtraLookupTable function does that step.
		
		if( val == 0):
			continue
		elif (val == 1):
			ResultsList.append(LookupTable.get(ba[val]))
			prevValue = ba[val]
		else:
			curValue = ba[val]
			if (curValue != 257):
				BuildExtraLookupTable(curValue, prevValue)
				ResultsList.append(LookupTable.get(ba[val]))
				prevValue= curValue
		
	logging.debug("")
	logging.debug("Decoded index list:")
	logging.debug(['0x%x' % j for j in ba])
	logging.debug("")


	resultData = ",".join(ResultsList)
	hChars = resultData.split(',')
	Output = ""
	for h in hChars:
		Output += chr(int(h,16))

	logging.debug("Retrieved config character array:")
	logging.debug(['0x%x' % int(m,16) for m in hChars])
	logging.debug("")

	TokenizedOutput = Output.split('\r\n')
	ConfigSections = ['Identity Code:','C2 Host/IP #1:','C2 Host/IP #2:','C2 Host/IP #3:','C2 Port #1:','C2 Port #2:','C2 Port #3:','Password:','Campaign ID:','']

	logging.warn("Configuration Data:")
	headr = "=" * 30
	logging.warn(headr)

	for x in range(len(TokenizedOutput)-1):
		logging.warn("%s\t%s" % (ConfigSections[x],TokenizedOutput[x]))

	logging.warn("")