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Add support for loading CCache Version 3 #1106

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merged 2 commits into from
Mar 11, 2022
Merged

Add support for loading CCache Version 3 #1106

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b8c8f9c
Add support for V3 ccache
reznok Jun 29, 2021
de0bfa4
Update KeyBlock name
reznok Jun 29, 2021
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79 changes: 60 additions & 19 deletions impacket/krb5/ccache.py
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Original file line number Diff line number Diff line change
Expand Up @@ -56,7 +56,22 @@ class CountedOctetString(Structure):
def prettyPrint(self, indent=''):
return "%s%s" % (indent, hexlify(self['data']))

class KeyBlock(Structure):

class KeyBlockV3(Structure):
structure = (
('keytype','!H=0'),
('etype','!H=0'),
('etype2', '!H=0'), # Version 3 repeats the etype
('keylen','!H=0'),
('_keyvalue','_-keyvalue','self["keylen"]'),
('keyvalue',':'),
)

def prettyPrint(self):
return "Key: (0x%x)%s" % (self['keytype'], hexlify(self['keyvalue']))


class KeyBlockV4(Structure):
structure = (
('keytype','!H=0'),
('etype','!H=0'),
Expand Down Expand Up @@ -165,26 +180,41 @@ def toPrincipal(self):
return types.Principal(self.prettyPrint(), type=self.header['name_type'])

class Credential:
class CredentialHeader(Structure):
class CredentialHeaderV3(Structure):
structure = (
('client',':', Principal),
('server',':', Principal),
('key',':', KeyBlock),
('key',':', KeyBlockV3),
('time',':', Times),
('is_skey','B=0'),
('tktflags','!L=0'),
('num_address','!L=0'),
)

def __init__(self, data=None):
class CredentialHeaderV4(Structure):
structure = (
('client',':', Principal),
('server',':', Principal),
('key',':', KeyBlockV4),
('time',':', Times),
('is_skey','B=0'),
('tktflags','!L=0'),
('num_address','!L=0'),
)

def __init__(self, data=None, ccache_version=None):
self.addresses = ()
self.authData = ()
self.header = None
self.ticket = None
self.secondTicket = None

if data is not None:
self.header = self.CredentialHeader(data)
if ccache_version == 3:
self.header = self.CredentialHeaderV3(data)
else:
self.header = self.CredentialHeaderV4(data)

data = data[len(self.header):]
self.addresses = []
for address in range(self.header['num_address']):
Expand All @@ -202,7 +232,7 @@ def __init__(self, data=None):
self.secondTicket = CountedOctetString(data)
data = data[len( self.secondTicket):]
else:
self.header = self.CredentialHeader()
self.header = self.CredentialHeaderV4()

def __getitem__(self, key):
return self.header[key]
Expand Down Expand Up @@ -308,7 +338,10 @@ def toTGS(self, newSPN=None):
tgs['sessionKey'] = crypto.Key(cipher.enctype, self['key']['keyvalue'])
return tgs


class CCache:
# https://web.mit.edu/kerberos/krb5-devel/doc/formats/ccache_file_format.html

class MiniHeader(Structure):
structure = (
('file_format_version','!H=0x0504'),
Expand All @@ -321,17 +354,25 @@ def __init__(self, data = None):
self.credentials = []
self.miniHeader = None
if data is not None:
miniHeader = self.MiniHeader(data)
data = data[len(miniHeader.getData()):]
ccache_version = data[1]

headerLen = miniHeader['headerlen']
# Only Version 4 contains a header
if ccache_version == 4:
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miniHeader = self.MiniHeader(data)
data = data[len(miniHeader.getData()):]

self.headers = []
while headerLen > 0:
header = Header(data)
self.headers.append(header)
headerLen -= len(header)
data = data[len(header):]
headerLen = miniHeader['headerlen']

self.headers = []
while headerLen > 0:
header = Header(data)
self.headers.append(header)
headerLen -= len(header)
data = data[len(header):]

else:
# Skip over the version bytes
data = data[2:]

# Now the primary_principal
self.principal = Principal(data)
Expand All @@ -341,7 +382,7 @@ def __init__(self, data = None):
# Now let's parse the credentials
self.credentials = []
while len(data) > 0:
cred = Credential(data)
cred = Credential(data, ccache_version)
if cred['server'].prettyPrint().find(b'krb5_ccache_conf_data') < 0:
self.credentials.append(cred)
data = data[len(cred.getData()):]
Expand Down Expand Up @@ -429,7 +470,7 @@ def fromTGT(self, tgt, oldSessionKey, sessionKey):
credential['server'] = tmpServer
credential['is_skey'] = 0

credential['key'] = KeyBlock()
credential['key'] = KeyBlockV4()
credential['key']['keytype'] = int(encASRepPart['key']['keytype'])
credential['key']['keyvalue'] = encASRepPart['key']['keyvalue'].asOctets()
credential['key']['keylen'] = len(credential['key']['keyvalue'])
Expand Down Expand Up @@ -489,7 +530,7 @@ def fromTGS(self, tgs, oldSessionKey, sessionKey):
credential['server'] = tmpServer
credential['is_skey'] = 0

credential['key'] = KeyBlock()
credential['key'] = KeyBlockV4()
credential['key']['keytype'] = int(encTGSRepPart['key']['keytype'])
credential['key']['keyvalue'] = encTGSRepPart['key']['keyvalue'].asOctets()
credential['key']['keylen'] = len(credential['key']['keyvalue'])
Expand Down Expand Up @@ -571,7 +612,7 @@ def fromKRBCRED(self, encodedKrbCred):
credential['server'] = tmpServer
credential['is_skey'] = 0

credential['key'] = KeyBlock()
credential['key'] = KeyBlockV4()
credential['key']['keytype'] = int(krbCredInfo['key']['keytype'])
credential['key']['keyvalue'] = str(krbCredInfo['key']['keyvalue'])
credential['key']['keylen'] = len(credential['key']['keyvalue'])
Expand Down