Extract everything from WannaCry

wcr.py

import re
import os,sys
import pefile
import struct
import zipfile
import hashlib
import StringIO
from Crypto import Random
from Crypto.PublicKey import RSA
from Crypto.Cipher import PKCS1_v1_5,AES


RSA_re = re.compile(r'RSA(1|2)')
get_urls = lambda d: map(lambda x:x.strip("\x00"),re.findall("https?://[\x1f-\x7e]{6,}\x00",d))
get_strings = lambda d: re.findall('[ -~]{3,}',d)
BTC_re = re.compile('^[13][a-km-zA-HJ-NP-Z1-9]{25,34}$')

def get_rsc(pe,pred):
    def walk_rsc(d):
        if pred(pe,d):
            x = d.data.struct
            return pe.get_data(x.OffsetToData,x.Size)
    
        if not hasattr(d,'directory'): return None
    
        for d in d.directory.entries:
            r = walk_rsc(d)
            if r: return r
        
    for d in pe.DIRECTORY_ENTRY_RESOURCE.entries:
        r=walk_rsc(d)
        if r:return r

def rsc_pe_pred(pe,d):
    return  hasattr(d,'data') and pe.get_data(d.data.struct.OffsetToData,  2) == 'MZ'

def rsc_zip_pred(pe,d):
    return  hasattr(d,'data') and pe.get_data(d.data.struct.OffsetToData,  2) == 'PK'


def try_passwd(zipf,f,pw):
    try:
        zp = zipfile.ZipFile(StringIO.StringIO(zipf))
        return zp.open(f,'r',pw).read()
    except Exception as e:
        return False

class RSAKEY(object):

    def __init__(self,d):
        self.bin = d
        self.off = 0 
        self.bits = 0
    def get_int(self,b):
        r=long(self.bin[self.off:self.off+self.bits/b][::-1].encode('hex'),16)
        self.off += self.bits/b
        return r

    def unpack(self):

        if self.bin[0] not in ["\x06","\x07"]:
            return None

        if self.bin[8:12] not in ['RSA1','RSA2']:
            return None
        key = {}
        priv = self.bin[0] == "\x07"
        self.bits,key['e'] = struct.unpack('II',self.bin[12:20])
        self.off = 20
        key['n']= self.get_int(8)
        if priv:
            key['p1'] = self.get_int(16)
            key['p2'] = self.get_int(16)
            key['exp1'] = self.get_int(16)
            key['exp2'] = self.get_int(16)
            key['coeff'] = self.get_int(16)
            key['d'] = self.get_int(8)
            ko = RSA.construct((key['n'],long(key['e']),key['d']))
        else:
            ko = RSA.construct((key['n'],long(key['e'])))
        return ko,key
    
def decode_aes_key(key,data):
    ## stolen from https://github.com/sysopfb/Malware_Scripts/blob/master/wannacry/decode_dll.py
    ## kudos to sysopfb
    cipher = PKCS1_v1_5.new(key)

    sentinel = Random.new().read(16)
    d = cipher.decrypt(data[::-1],sentinel)
    return d

def check_hdr(bin):
    return True


def handle_dropper(fpath):
    pe = pefile.PE(sys.argv[1])
    for s in pe.sections:
        if s.Name.startswith('.data'):
            url = get_urls(s.get_data())[0]
            print '[+] Kill-Switch/Sandbox check url',url
            break
    return get_rsc(pe,rsc_pe_pred)
try:
    inner_exe = handle_dropper(sys.argv[1])
    pe2= pefile.PE(data=inner_exe)
    print '[+] got dropper'
    drop = True
except Exception as e:
    drop= False
    pe2 = pefile.PE(sys.argv[1])
    inner_exe = open(sys.argv[1]).read()
    print '[+] got inner loader'
    
inner_zip =get_rsc(pe2,rsc_zip_pred)
cfg_files = []
for s in pe2.sections:
    if s.Name.startswith('.data'):
        data_s = s
        strings= get_strings(s.get_data())
        for st in strings:
            if BTC_re.match(st):
                print '[+] bitcoin address', st
            elif st.endswith('.wnry'):
                print '[*] possible configuration file', st
                cfg_files.append(st)
            elif st.startswith('Global'):
                print '[+] Mutex',st


# for s in cfg_files:
#     try_passwd(inner_zip,s,'')

for s in strings:
     if try_passwd(inner_zip,cfg_files[0],s):
         print '[+] zip password',s
         passwd = s
for f in cfg_files:
    d= try_passwd(inner_zip,f,passwd)
    if 'onion' in d:
        print '[+] Configuration file',f
        urls = get_strings(d)[0]
        print '[+] payment sites:\n ',
        print '\n  '.join(urls.split(';'))
    else:
        end_dll = d

off = RSA_re.finditer(inner_exe).next().start() - 8
ko,key = RSAKEY(inner_exe[off:]).unpack()
print '[+] 1st Embeded RSA key'
print ko.exportKey()
if not check_hdr(end_dll):
    print '[-] wrong file...'
    
(_, size) = struct.unpack('<IQ', end_dll[12+256:12+256+12])
aes_key = decode_aes_key(ko,end_dll[12:256+12])
c = AES.new(aes_key, AES.MODE_CBC, '\x00'*16)
core=c.decrypt(end_dll[24+256:24+256+size])

if drop:
    fname = 'inner.%s.exe' % hashlib.sha256(inner_exe).hexdigest()
    print '[+] saving inner loader as', fname
    with open('/tmp/' + fname,'w') as f:
        f.write(inner_exe)

fname = 'inner.%s.zip' % hashlib.sha256(inner_zip).hexdigest()
print '[+] saving inner zip as', fname
with open('/tmp/' + fname,'w') as f:
        f.write(inner_zip)
print '[+] embeded keys:'
for g in RSA_re.finditer(core):
    ko,_ = RSAKEY(core[g.start()-8:]).unpack()
    print ko.exportKey()

        
fname = 'core.%s.dll' % hashlib.sha256(core).hexdigest()
print '[+] saving core dll as', fname
with open('/tmp/' + fname,'w') as f:
        f.write(core)