Base64Unpack.rst

Base64 Decoding and Unpacking ============================= This module allows you to extract base64 encoded content from a string or columns of a Pandas DataFrame. The library returns the following information: - decoded string (if decodable to utf-8 or utf-16) - hashes of the decoded segment (MD5, SHA1, SHA256) - string of printable byte values (e.g. for submission to a disassembler) - the detected decoded file type (limited) If the results of the decoding contain further encoded strings these will be decoded recursively. If the encoded string appears to be a zip, gzip or tar archive, the contents will be decompressed after decoding. In the case of zip and tar, the contents of the archive will also be checked for base64 encoded content and decoded/decompressed if possible. See :py:mod:`b64decode` .. code:: python # Imports import sys MIN_REQ_PYTHON = (3,6) if sys.version_info < MIN_REQ_PYTHON: print('Check the Kernel->Change Kernel menu and ensure that Python 3.6') print('or later is selected as the active kernel.') sys.exit("Python %s.%s or later is required.\n" % MIN_REQ_PYTHON) from IPython.display import display import pandas as pd # Import Base64 module from msticpy.nbtools import * from msticpy.sectools import * .. container:: cell code .. code:: python # Load test data process_tree = pd.read_csv('data/process_tree.csv', parse_dates=["TimeGenerated"], infer_datetime_format=True) process_tree[['CommandLine']].head() .. container:: output execute_result :: CommandLine 0 .\ftp -s:C:\RECYCLER\xxppyy.exe 1 .\reg not /domain:everything that /sid:shines... 2 cmd /c "systeminfo && systeminfo" 3 .\rundll32 /C 12345.exe 4 .\rundll32 /C c:\users\MSTICAdmin\12345.exe Base64 decode an input string ----------------------------- unpack(input_string=cmdline) See :py:func:`unpack` Items that decode to utf-8 or utf-16 strings will be returned as decoded strings replaced in the original string. If the encoded string is a known binary type it will identify the file type and return the hashes of the file. If any binary types are known archives (zip, tar, gzip) it will unpack the contents of the archive. For any binary it will return the decoded file as a byte array, and as a printable list of byte values. The function a tuple of the decoded string and a pandas DataFrame of metadata (hashes, list of byte values, etc.) .. container:: cell code .. code:: python # get a commandline from our data set cmdline = process_tree['CommandLine'].loc[39] cmdline .. container:: output execute_result :: '.\\powershell -enc JAB0ACAAPQAgACcAZABpAHIAJwA7AA0ACgAmACAAKAAnAEkAbgB2AG8AawBlACcAKwAnAC0ARQB4AHAAcgBlAHMAcwBpAG8AbgAnACkAIAAkAHQA' .. container:: cell code .. code:: python # Decode the string base64_dec_str = base64.unpack(input_string=cmdline) # Print decoded string print(base64_dec_str) .. container:: output stream stdout :: (".\\powershell -enc $\x00t\x00 \x00=\x00 \x00'\x00d\x00i\x00r\x00'\x00;\x00\r\x00\n\x00&\x00 \x00(\x00'\x00I\x00n\x00v\x00o\x00k\x00e\x00'\x00+\x00'\x00-\x00E\x00x\x00p\x00r\x00e\x00s\x00s\x00i\x00o\x00n\x00'\x00)\x00 \x00$\x00t\x00", reference original_string file_name \ 0 (, 1., 1) JAB0ACAAPQAgACcAZABpAHIAJwA7AA0ACgAmACAAKAAnAE... unknown file_type input_bytes \ 0 None b"$\x00t\x00 \x00=\x00 \x00'\x00d\x00i\x00r\x0... decoded_string encoding_type \ 0 $t = 'dir';\r\n& ('Invok... utf-8 file_hashes \ 0 {'md5': '6cd1486db221e532cc2011c9beeb4ffc', 's... md5 sha1 \ 0 6cd1486db221e532cc2011c9beeb4ffc 6e485467d7e06502046b7c84a8ef067cfe1512ad sha256 \ 0 d3291dab1ae552b91e6b50d7460ceaa39f6f92b2cda433... printable_bytes 0 24 00 74 00 20 00 3d 00 20 00 27 00 64 00 69 0... ) Using a DataFrame as input -------------------------- You can use :py:func:`unpack_df` to pass a DataFrame as an argument. Use the ``column`` parameter to specify which column to process. In the case of DataFrame input, the output DataFrame contains these additional columns: - src_index - the index of the row in the input dataframe from which the data came. - full_decoded_string - the full decoded string with any decoded replacements. This is only really useful for top-level items, since nested items will only show the 'full' string representing the child fragment. Base64 decode strings taken from a pandas dataframe. Items that decode to utf-8 or utf-16 strings will be returned as decoded strings replaced in the original string. If the encoded string is a known binary type it will identify the file type and return the hashes of the file. If any binary types are known archives (zip, tar, gzip) it will unpack the contents of the archive. For any binary it will return the decoded file as a byte array, and as a printable list of byte values. .. container:: cell code .. code:: python # specify the data and column parameters dec_df = base64.unpack_df(data=process_tree, column='CommandLine') dec_df .. container:: output execute_result :: reference original_string file_name \ 0 (, 1., 1) JAB0ACAAPQAgACcAZABpAHIAJwA7AA0ACgAmACAAKAAnAE... unknown 1 (, 1., 1) aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa unknown 2 (, 1., 1) aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa unknown 3 (, 1., 1) 81ed03caf6901e444c72ac67d192fb9c unknown file_type input_bytes \ 0 None b"$\x00t\x00 \x00=\x00 \x00'\x00d\x00i\x00r\x0... 1 None b'i\xa6\x9ai\xa6\x9ai\xa6\x9ai\xa6\x9ai\xa6\x9... 2 None b'i\xa6\x9ai\xa6\x9ai\xa6\x9ai\xa6\x9ai\xa6\x9... 3 None b'\xf3W\x9d\xd3w\x1a\x7f\xaft\xd5\xee8\xe1\xce... decoded_string encoding_type \ 0 $t = 'dir';\r\n& ('Invok... utf-8 1 ꙩ榚骦ꙩ榚骦ꙩ榚骦ꙩ榚骦 utf-16 2 ꙩ榚骦ꙩ榚骦ꙩ榚骦ꙩ榚骦 utf-16 3 埳펝᩷꽿해㣮컡槶믎彷絶岿 utf-16 file_hashes \ 0 {'md5': '6cd1486db221e532cc2011c9beeb4ffc', 's... 1 {'md5': '9a45b2520e930dc9186f6d93a7798a13', 's... 2 {'md5': '9a45b2520e930dc9186f6d93a7798a13', 's... 3 {'md5': '1c8cc6299bd654bbcd85710968d6a87c', 's... md5 sha1 \ 0 6cd1486db221e532cc2011c9beeb4ffc 6e485467d7e06502046b7c84a8ef067cfe1512ad 1 9a45b2520e930dc9186f6d93a7798a13 f526c90fa0744e3a63d84421ff25e3f5a3d697cb 2 9a45b2520e930dc9186f6d93a7798a13 f526c90fa0744e3a63d84421ff25e3f5a3d697cb 3 1c8cc6299bd654bbcd85710968d6a87c 55377391141f59a2ff5ae4765d9f0b4438adfd73 sha256 \ 0 d3291dab1ae552b91e6b50d7460ceaa39f6f92b2cda433... 1 c1f6c05bdbe28a58557a9477cd0fa96fbc5e7c54ceb605... 2 c1f6c05bdbe28a58557a9477cd0fa96fbc5e7c54ceb605... 3 fd80ceba7cfb49d296886c10d9a3497d63c89a589587cd... printable_bytes src_index \ 0 24 00 74 00 20 00 3d 00 20 00 27 00 64 00 69 0... 39 1 69 a6 9a 69 a6 9a 69 a6 9a 69 a6 9a 69 a6 9a 6... 40 2 69 a6 9a 69 a6 9a 69 a6 9a 69 a6 9a 69 a6 9a 6... 41 3 f3 57 9d d3 77 1a 7f af 74 d5 ee 38 e1 ce f6 6... 44 full_decoded_string 0 .\powershell -enc 笾뿴䅐〳⌁㾝䲍ǔ庰퀈쐿Č熠倀℈ꚜᨒ腦㽋ꚩ黓恓⊀́�᠀菀ﳶ态ꨭꪪꪪꪪꪪꪪꨊ᪪耚ⶡꪪꪪꪪꪪ⪪ᆢ죺ſﵠ쀇׿ﾀ쀇׿｀䘁대䀃蜨榑v⃈Σ ። Base64 encoded string in zip file Unencoded text file in zip IPython magic ------------- You can use the cell magic ``%%b64`` to decode text directly in a cell The b64 magic supports the following options: :: --out OUT, -o OUT The variable to return the results in the variable `OUT` Note: the output is a tuple of decoded string and pandas DataFrame --pretty, -p Print formatted version of output (if you `print` the output) --clean, -c Print decoded string with no formatting .. code:: ipython3 %%b64 --pretty --out dec_xml powershell.exe -nop -w hidden -encodedcommand UEsDBBQAAAAIAGBXkk3LfdszdwAAAIoAAAAJAAAAUGVEbGwuZGxss6v+sj/A0diA UXmufa/PFcYNcRwX7I/wMC4oZAjgUJyzTEgqrdHbfuWyy/OCExqUGJkZGBoYoEDi QPO3P4wJuqsQgGvVKimphoUIIa1Fgr9OMLyoZ0z4y37gP2vDfxDp8J/RjWEzs4NG +8TMMoYTCouZGRSShAFQSwMEFAAAAAAAYYJrThx8YzUhAAAAIQAAAAwAAABiNjRp bnppcC5mb29CYXNlNjQgZW5jb2RlZCBzdHJpbmcgaW4gemlwIGZpbGVQSwMEFAAA AAAAi4JrTvMfsJUaAAAAGgAAABIAAABQbGFpblRleHRJblppcC5kbGxVbmVuY29k ZWQgdGV4dCBmaWxlIGluIHppcFBLAQIUABQAAAAIAGBXkk3LfdszdwAAAIoAAAAJ AAAAAAAAAAAAIAAAAAAAAABQZURsbC5kbGxQSwECFAAUAAAAAABhgmtOHHxjNSEA AAAhAAAADAAAAAAAAAABACAAAACeAAAAYjY0aW56aXAuZm9vUEsBAhQAFAAAAAAA i4JrTvMfsJUaAAAAGgAAABIAAAAAAAAAAQAgAAAA6QAAAFBsYWluVGV4dEluWmlw LmRsbFBLBQYAAAAAAwADALEAAAAzAQAAAAA= .. parsed-literal:: '\n\n powershell.exe -nop -w hidden -encodedcommand\n \n \n 3e 7b f4 bf 50 41 33 30 01 23 9d 3f 8d 4c d4 01 b0 5e 08 d0 3f c4 0c 01 a0 71 00 50 08 21 9c a6 12 1a 66 81 4b 3f a9 a6 d3 9e 53 60 80 22 01 03 00 00 80 00 00 00 00 00 00 00 00 18 c0 83 f6 fc 01 60 2d aa aa aa aa aa aa aa aa aa aa aa 0a aa aa 1a 1a 80 a1 2d aa aa aa aa aa aa aa aa aa 2a a2 11 fa c8 00 e8 7f 01 60 fd 07 c0 ff 05 80 ff 07 c0 ff 05 40 ff 01 46 00 b3 03 40 28 87 91 69 76 00 c8 20 a3 03 00 20 62 13\n \n \n Base64 encoded string in zip file\n \n \n Unencoded text file in zip\n \n \n' Display the pretty-printed version of the decoded string. .. code:: ipython3 print(dec_xml[0]) .. parsed-literal:: powershell.exe -nop -w hidden -encodedcommand 3e 7b f4 bf 50 41 33 30 01 23 9d 3f 8d 4c d4 01 b0 5e 08 d0 3f c4 0c 01 a0 71 00 50 08 21 9c a6 12 1a 66 81 4b 3f a9 a6 d3 9e 53 60 80 22 01 03 00 00 80 00 00 00 00 00 00 00 00 18 c0 83 f6 fc 01 60 2d aa aa aa aa aa aa aa aa aa aa aa 0a aa aa 1a 1a 80 a1 2d aa aa aa aa aa aa aa aa aa 2a a2 11 fa c8 00 e8 7f 01 60 fd 07 c0 ff 05 80 ff 07 c0 ff 05 40 ff 01 46 00 b3 03 40 28 87 91 69 76 00 c8 20 a3 03 00 20 62 13 Base64 encoded string in zip file Unencoded text file in zip Pandas Extension ---------------- The decoding functionality is also available in a pandas extension ``mp_b64``. This supports a single method ``extract()``. This supports the same syntax as ``unpack_df`` (described earlier). It returns a DataFrame with the decoded contents (this may be multiple output lines for inputs where there is a nested encoding. .. code:: ipython3 process_tree.mp_b64.extract(column='CommandLine') .. container:: cell markdown .. rubric:: To-Do Items :name: to-do-items - Use more comprehensive list of binary magic numbers and match on byte values after decoding to get better file typing - Output nested decodings in a more readable output - Add a pandas pipe() partial function to allow inline decoding in a pands pipeline. E.g. ``my_df = pd.read_cs('input.csv').b64decode(column='CommandLine').drop_duplicates().some_func()``