import io
import logging
import shutil
import tempfile
from collections import namedtuple
from struct import pack, unpack
import olefile
from msoffcrypto import exceptions
from msoffcrypto.format import base
from msoffcrypto.format.common import _parse_header_RC4CryptoAPI
from msoffcrypto.method.rc4 import DocumentRC4
from msoffcrypto.method.rc4_cryptoapi import DocumentRC4CryptoAPI
from msoffcrypto.method.xor_obfuscation import DocumentXOR
logger = logging.getLogger(__name__)
logger.addHandler(logging.NullHandler())
recordNameNum = {
"Formula": 6,
"EOF": 10,
"CalcCount": 12,
"CalcMode": 13,
"CalcPrecision": 14,
"CalcRefMode": 15,
"CalcDelta": 16,
"CalcIter": 17,
"Protect": 18,
"Password": 19,
"Header": 20,
"Footer": 21,
"ExternSheet": 23,
"Lbl": 24,
"WinProtect": 25,
"VerticalPageBreaks": 26,
"HorizontalPageBreaks": 27,
"Note": 28,
"Selection": 29,
"Date1904": 34,
"ExternName": 35,
"LeftMargin": 38,
"RightMargin": 39,
"TopMargin": 40,
"BottomMargin": 41,
"PrintRowCol": 42,
"PrintGrid": 43,
"FilePass": 47,
"Font": 49,
"PrintSize": 51,
"Continue": 60,
"Window1": 61,
"Backup": 64,
"Pane": 65,
"CodePage": 66,
"Pls": 77,
"DCon": 80,
"DConRef": 81,
"DConName": 82,
"DefColWidth": 85,
"XCT": 89,
"CRN": 90,
"FileSharing": 91,
"WriteAccess": 92,
"Obj": 93,
"Uncalced": 94,
"CalcSaveRecalc": 95,
"Template": 96,
"Intl": 97,
"ObjProtect": 99,
"ColInfo": 125,
"Guts": 128,
"WsBool": 129,
"GridSet": 130,
"HCenter": 131,
"VCenter": 132,
"BoundSheet8": 133,
"WriteProtect": 134,
"Country": 140,
"HideObj": 141,
"Sort": 144,
"Palette": 146,
"Sync": 151,
"LPr": 152,
"DxGCol": 153,
"FnGroupName": 154,
"FilterMode": 155,
"BuiltInFnGroupCount": 156,
"AutoFilterInfo": 157,
"AutoFilter": 158,
"Scl": 160,
"Setup": 161,
"ScenMan": 174,
"SCENARIO": 175,
"SxView": 176,
"Sxvd": 177,
"SXVI": 178,
"SxIvd": 180,
"SXLI": 181,
"SXPI": 182,
"DocRoute": 184,
"RecipName": 185,
"MulRk": 189,
"MulBlank": 190,
"Mms": 193,
"SXDI": 197,
"SXDB": 198,
"SXFDB": 199,
"SXDBB": 200,
"SXNum": 201,
"SxBool": 202,
"SxErr": 203,
"SXInt": 204,
"SXString": 205,
"SXDtr": 206,
"SxNil": 207,
"SXTbl": 208,
"SXTBRGIITM": 209,
"SxTbpg": 210,
"ObProj": 211,
"SXStreamID": 213,
"DBCell": 215,
"SXRng": 216,
"SxIsxoper": 217,
"BookBool": 218,
"DbOrParamQry": 220,
"ScenarioProtect": 221,
"OleObjectSize": 222,
"XF": 224,
"InterfaceHdr": 225,
"InterfaceEnd": 226,
"SXVS": 227,
"MergeCells": 229,
"BkHim": 233,
"MsoDrawingGroup": 235,
"MsoDrawing": 236,
"MsoDrawingSelection": 237,
"PhoneticInfo": 239,
"SxRule": 240,
"SXEx": 241,
"SxFilt": 242,
"SxDXF": 244,
"SxItm": 245,
"SxName": 246,
"SxSelect": 247,
"SXPair": 248,
"SxFmla": 249,
"SxFormat": 251,
"SST": 252,
"LabelSst": 253,
"ExtSST": 255,
"SXVDEx": 256,
"SXFormula": 259,
"SXDBEx": 290,
"RRDInsDel": 311,
"RRDHead": 312,
"RRDChgCell": 315,
"RRTabId": 317,
"RRDRenSheet": 318,
"RRSort": 319,
"RRDMove": 320,
"RRFormat": 330,
"RRAutoFmt": 331,
"RRInsertSh": 333,
"RRDMoveBegin": 334,
"RRDMoveEnd": 335,
"RRDInsDelBegin": 336,
"RRDInsDelEnd": 337,
"RRDConflict": 338,
"RRDDefName": 339,
"RRDRstEtxp": 340,
"LRng": 351,
"UsesELFs": 352,
"DSF": 353,
"CUsr": 401,
"CbUsr": 402,
"UsrInfo": 403,
"UsrExcl": 404,
"FileLock": 405,
"RRDInfo": 406,
"BCUsrs": 407,
"UsrChk": 408,
"UserBView": 425,
"UserSViewBegin": 426,
"UserSViewBegin_Chart": 426,
"UserSViewEnd": 427,
"RRDUserView": 428,
"Qsi": 429,
"SupBook": 430,
"Prot4Rev": 431,
"CondFmt": 432,
"CF": 433,
"DVal": 434,
"DConBin": 437,
"TxO": 438,
"RefreshAll": 439,
"HLink": 440,
"Lel": 441,
"CodeName": 442,
"SXFDBType": 443,
"Prot4RevPass": 444,
"ObNoMacros": 445,
"Dv": 446,
"Excel9File": 448,
"RecalcId": 449,
"EntExU2": 450,
"Dimensions": 512,
"Blank": 513,
"Number": 515,
"Label": 516,
"BoolErr": 517,
"String": 519,
"Row": 520,
"Index": 523,
"Array": 545,
"DefaultRowHeight": 549,
"Table": 566,
"Window2": 574,
"RK": 638,
"Style": 659,
"BigName": 1048,
"Format": 1054,
"ContinueBigName": 1084,
"ShrFmla": 1212,
"HLinkTooltip": 2048,
"WebPub": 2049,
"QsiSXTag": 2050,
"DBQueryExt": 2051,
"ExtString": 2052,
"TxtQry": 2053,
"Qsir": 2054,
"Qsif": 2055,
"RRDTQSIF": 2056,
"BOF": 2057,
"OleDbConn": 2058,
"WOpt": 2059,
"SXViewEx": 2060,
"SXTH": 2061,
"SXPIEx": 2062,
"SXVDTEx": 2063,
"SXViewEx9": 2064,
"ContinueFrt": 2066,
"RealTimeData": 2067,
"ChartFrtInfo": 2128,
"FrtWrapper": 2129,
"StartBlock": 2130,
"EndBlock": 2131,
"StartObject": 2132,
"EndObject": 2133,
"CatLab": 2134,
"YMult": 2135,
"SXViewLink": 2136,
"PivotChartBits": 2137,
"FrtFontList": 2138,
"SheetExt": 2146,
"BookExt": 2147,
"SXAddl": 2148,
"CrErr": 2149,
"HFPicture": 2150,
"FeatHdr": 2151,
"Feat": 2152,
"DataLabExt": 2154,
"DataLabExtContents": 2155,
"CellWatch": 2156,
"FeatHdr11": 2161,
"Feature11": 2162,
"DropDownObjIds": 2164,
"ContinueFrt11": 2165,
"DConn": 2166,
"List12": 2167,
"Feature12": 2168,
"CondFmt12": 2169,
"CF12": 2170,
"CFEx": 2171,
"XFCRC": 2172,
"XFExt": 2173,
"AutoFilter12": 2174,
"ContinueFrt12": 2175,
"MDTInfo": 2180,
"MDXStr": 2181,
"MDXTuple": 2182,
"MDXSet": 2183,
"MDXProp": 2184,
"MDXKPI": 2185,
"MDB": 2186,
"PLV": 2187,
"Compat12": 2188,
"DXF": 2189,
"TableStyles": 2190,
"TableStyle": 2191,
"TableStyleElement": 2192,
"StyleExt": 2194,
"NamePublish": 2195,
"NameCmt": 2196,
"SortData": 2197,
"Theme": 2198,
"GUIDTypeLib": 2199,
"FnGrp12": 2200,
"NameFnGrp12": 2201,
"MTRSettings": 2202,
"CompressPictures": 2203,
"HeaderFooter": 2204,
"CrtLayout12": 2205,
"CrtMlFrt": 2206,
"CrtMlFrtContinue": 2207,
"ForceFullCalculation": 2211,
"ShapePropsStream": 2212,
"TextPropsStream": 2213,
"RichTextStream": 2214,
"CrtLayout12A": 2215,
"Units": 4097,
"Chart": 4098,
"Series": 4099,
"DataFormat": 4102,
"LineFormat": 4103,
"MarkerFormat": 4105,
"AreaFormat": 4106,
"PieFormat": 4107,
"AttachedLabel": 4108,
"SeriesText": 4109,
"ChartFormat": 4116,
"Legend": 4117,
"SeriesList": 4118,
"Bar": 4119,
"Line": 4120,
"Pie": 4121,
"Area": 4122,
"Scatter": 4123,
"CrtLine": 4124,
"Axis": 4125,
"Tick": 4126,
"ValueRange": 4127,
"CatSerRange": 4128,
"AxisLine": 4129,
"CrtLink": 4130,
"DefaultText": 4132,
"Text": 4133,
"FontX": 4134,
"ObjectLink": 4135,
"Frame": 4146,
"Begin": 4147,
"End": 4148,
"PlotArea": 4149,
"Chart3d": 4154,
"PicF": 4156,
"DropBar": 4157,
"Radar": 4158,
"Surf": 4159,
"RadarArea": 4160,
"AxisParent": 4161,
"LegendException": 4163,
"ShtProps": 4164,
"SerToCrt": 4165,
"AxesUsed": 4166,
"SBaseRef": 4168,
"SerParent": 4170,
"SerAuxTrend": 4171,
"IFmtRecord": 4174,
"Pos": 4175,
"AlRuns": 4176,
"BRAI": 4177,
"SerAuxErrBar": 4187,
"ClrtClient": 4188,
"SerFmt": 4189,
"Chart3DBarShape": 4191,
"Fbi": 4192,
"BopPop": 4193,
"AxcExt": 4194,
"Dat": 4195,
"PlotGrowth": 4196,
"SIIndex": 4197,
"GelFrame": 4198,
"BopPopCustom": 4199,
"Fbi2": 4200,
}
def _parse_header_RC4(encryptionInfo):
# RC4: https://msdn.microsoft.com/en-us/library/dd908560(v=office.12).aspx
salt = encryptionInfo.read(16)
encryptedVerifier = encryptionInfo.read(16)
encryptedVerifierHash = encryptionInfo.read(16)
info = {
"salt": salt,
"encryptedVerifier": encryptedVerifier,
"encryptedVerifierHash": encryptedVerifierHash,
}
return info
class _BIFFStream:
def __init__(self, data):
self.data = data
def has_record(self, target):
pos = self.data.tell()
while True:
h = self.data.read(4)
if not h:
self.data.seek(pos)
return False
num, size = unpack("<HH", h)
if num == target:
self.data.seek(pos)
return True
else:
self.data.read(size)
def skip_to(self, target):
while True:
h = self.data.read(4)
if not h:
raise exceptions.ParseError("Record not found")
num, size = unpack("<HH", h)
if num == target:
return num, size
else:
self.data.read(size)
def iter_record(self):
while True:
h = self.data.read(4)
if not h:
break
num, size = unpack("<HH", h)
record = io.BytesIO(self.data.read(size))
yield num, size, record
class Xls97File(base.BaseOfficeFile):
"""Return a MS-XLS file object.
Examples:
>>> with open("tests/inputs/rc4cryptoapi_password.xls", "rb") as f:
... officefile = Xls97File(f)
... officefile.load_key(password="Password1234_")
>>> with open("tests/inputs/xor_password_123456789012345.xls", "rb") as f:
... officefile = Xls97File(f)
... officefile.load_key(password="123456789012345")
>>> with open("tests/inputs/rc4cryptoapi_password.xls", "rb") as f:
... officefile = Xls97File(f)
... officefile.load_key(password="0000")
Traceback (most recent call last):
...
msoffcrypto.exceptions.InvalidKeyError: ...
"""
def __init__(self, file):
self.file = file
ole = olefile.OleFileIO(file) # do not close this, would close file
self.ole = ole
self.format = "xls97"
self.keyTypes = ["password"]
self.key = None
self.salt = None
workbook = ole.openstream("Workbook") # closed in destructor
Data = namedtuple("Data", ["workbook"])
self.data = Data(
workbook=workbook,
)
def __del__(self):
"""Destructor, closes opened stream."""
if hasattr(self, "data") and self.data and self.data.workbook:
self.data.workbook.close()
def load_key(self, password=None):
self.data.workbook.seek(0)
workbook = _BIFFStream(self.data.workbook)
# workbook stream consists of records, each of which begins with its ID number.
# Record IDs (in decimal) are listed here: https://msdn.microsoft.com/en-us/library/dd945945(v=office.12).aspx
# workbook stream's structure is WORKBOOK = BOF WORKBOOKCONTENT and so forth
# as in https://msdn.microsoft.com/en-us/library/dd952177(v=office.12).aspx
# A record begins with its length (in bytes).
(num,) = unpack("<H", workbook.data.read(2))
assert num == 2057 # BOF
(size,) = unpack("<H", workbook.data.read(2))
workbook.data.read(size) # Skip BOF
num, size = workbook.skip_to(
recordNameNum["FilePass"]
) # Skip to FilePass; TODO: Raise exception if not encrypted
# FilePass: https://msdn.microsoft.com/en-us/library/dd952596(v=office.12).aspx
# If this record exists, the workbook MUST be encrypted.
(wEncryptionType,) = unpack("<H", workbook.data.read(2))
encryptionInfo = io.BytesIO(workbook.data.read(size - 2))
if wEncryptionType == 0x0000: # XOR obfuscation
key, verificationBytes = unpack("<HH", encryptionInfo.read(4))
if DocumentXOR.verifypw(password, verificationBytes):
self.type = "xor"
self.key = password
self.loc_index = 0
else:
raise exceptions.InvalidKeyError("Failed to verify password")
elif wEncryptionType == 0x0001: # RC4
encryptionVersionInfo = encryptionInfo.read(4)
vMajor, vMinor = unpack("<HH", encryptionVersionInfo)
logger.debug("Version: {} {}".format(vMajor, vMinor))
if vMajor == 0x0001 and vMinor == 0x0001: # RC4
info = _parse_header_RC4(encryptionInfo)
if DocumentRC4.verifypw(
password,
info["salt"],
info["encryptedVerifier"],
info["encryptedVerifierHash"],
):
self.type = "rc4"
self.key = password
self.salt = info["salt"]
else:
raise exceptions.InvalidKeyError("Failed to verify password")
elif (
vMajor in [0x0002, 0x0003, 0x0004] and vMinor == 0x0002
): # RC4 CryptoAPI
info = _parse_header_RC4CryptoAPI(encryptionInfo)
if DocumentRC4CryptoAPI.verifypw(
password,
info["salt"],
info["keySize"],
info["encryptedVerifier"],
info["encryptedVerifierHash"],
):
self.type = "rc4_cryptoapi"
self.key = password
self.salt = info["salt"]
self.keySize = info["keySize"]
else:
raise exceptions.InvalidKeyError("Failed to verify password")
else:
raise exceptions.DecryptionError("Unsupported encryption method")
def decrypt(self, outfile):
# fd, _outfile_path = tempfile.mkstemp()
# shutil.copyfile(os.path.realpath(self.file.name), _outfile_path)
# outole = olefile.OleFileIO(_outfile_path, write_mode=True)
# List of encrypted parts: https://msdn.microsoft.com/en-us/library/dd905723(v=office.12).aspx
# Workbook stream
self.data.workbook.seek(0)
workbook = _BIFFStream(self.data.workbook)
plain_buf = []
encrypted_buf = io.BytesIO()
record_info = []
for i, (num, size, record) in enumerate(workbook.iter_record()):
# Remove encryption, pad by zero to preserve stream size
if num == recordNameNum["FilePass"]:
plain_buf += [0, 0] + list(pack("<H", size)) + [0] * size
encrypted_buf.write(b"\x00" * (4 + size))
# The following records MUST NOT be obfuscated or encrypted: BOF (section 2.4.21),
# FilePass (section 2.4.117), UsrExcl (section 2.4.339), FileLock (section 2.4.116),
# InterfaceHdr (section 2.4.146), RRDInfo (section 2.4.227), and RRDHead (section 2.4.226).
elif num in [
recordNameNum["BOF"],
recordNameNum["FilePass"],
recordNameNum["UsrExcl"],
recordNameNum["FileLock"],
recordNameNum["InterfaceHdr"],
recordNameNum["RRDInfo"],
recordNameNum["RRDHead"],
]:
header = pack("<HH", num, size)
plain_buf += list(header) + list(record.read())
encrypted_buf.write(b"\x00" * (4 + size))
# The lbPlyPos field of the BoundSheet8 record (section 2.4.28) MUST NOT be encrypted.
elif num == recordNameNum["BoundSheet8"]:
header = pack("<HH", num, size)
plain_buf += (
list(header) + list(record.read(4)) + [-2] * (size - 4)
) # Preserve lbPlyPos
encrypted_buf.write(b"\x00" * 4 + b"\x00" * 4 + record.read())
else:
header = pack("<HH", num, size)
plain_buf += list(header) + [-1] * size
encrypted_buf.write(b"\x00" * 4 + record.read())
self.data_size = encrypted_buf.tell()
encrypted_buf.seek(0)
if self.type == "rc4":
dec = DocumentRC4.decrypt(
self.key, self.salt, encrypted_buf, blocksize=1024
)
elif self.type == "rc4_cryptoapi":
dec = DocumentRC4CryptoAPI.decrypt(
self.key, self.salt, self.keySize, encrypted_buf, blocksize=1024
)
elif self.type == "xor":
dec = DocumentXOR.decrypt(
self.key, encrypted_buf, plain_buf, record_info, 10
)
else:
raise exceptions.DecryptionError(
"Unsupported encryption method: {}".format(self.type)
)
for c in plain_buf:
if c == -1 or c == -2:
dec.seek(1, 1)
else:
dec.write(bytearray([c]))
dec.seek(0)
# f = open('Workbook', 'wb')
# f.write(dec.read())
# dec.seek(0)
workbook_dec = dec
with tempfile.TemporaryFile() as _outfile:
self.file.seek(0)
shutil.copyfileobj(self.file, _outfile)
outole = olefile.OleFileIO(_outfile, write_mode=True)
outole.write_stream("Workbook", workbook_dec.read())
# _outfile = open(_outfile_path, 'rb')
_outfile.seek(0)
shutil.copyfileobj(_outfile, outfile)
return
def is_encrypted(self):
r"""
Test if the file is encrypted.
>>> f = open("tests/inputs/plain.xls", "rb")
>>> file = Xls97File(f)
>>> file.is_encrypted()
False
>>> f = open("tests/inputs/rc4cryptoapi_password.xls", "rb")
>>> file = Xls97File(f)
>>> file.is_encrypted()
True
"""
# Utilising the method above, check for encryption type.
self.data.workbook.seek(0)
workbook = _BIFFStream(self.data.workbook)
(num,) = unpack("<H", workbook.data.read(2))
assert num == 2057
(size,) = unpack("<H", workbook.data.read(2))
workbook.data.read(size)
if not workbook.has_record(recordNameNum["FilePass"]):
return False
num, size = workbook.skip_to(recordNameNum["FilePass"])
(wEncryptionType,) = unpack("<H", workbook.data.read(2))
if wEncryptionType == 0x0001: # RC4
return True
elif wEncryptionType == 0x0000: # XOR obfuscation
return True
else:
return False