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Due to the character of Python (interpreted language), securing the supply code is a difficult process. With a purpose to execute the supply code, it should be out there in some type.
All through this text, I’ll element the compiling modules with Cython methodology/answer to the problem of defending a Python-based codebase.
Cython is a static compiler for Python and Cython programming languages, it simplifies the job of writing Python C extensions. Cython permits us to compile Python code, the result’s dynamic libraries that can be utilized as python modules too.
The Cython import course of is as follows:
- shared library (.so, .pyd)
- python bytecode (.pyo, .pyc)
- python file (.py)
So… what are the advantages of utilizing Cython compiled modules?
- Binary modules will impose a a lot more durable process to get the unique Python code, reverse engineering methods should be used to take action.
- Cython generated C code might be modified to introduce adjustments, enhance safety, and so forth.
- GCC optimization flags can be utilized whereas compiling the library
- Tracebacks gained’t reveal code, however simply line numbers (except disabled ).
- Cython takes Python code and interprets it to C, which is then compiled by GCC (or comparable), the compiled code will run sooner than the pure Python model.
Let’s evaluate the essential performance of Cython
Keep in mind the hi there.py script from the HashiCorp Vault Secret Supervisor article? Properly, pulling secrets and techniques from HashiCorp Vault is nice however If you concentrate on it… if the person can entry/modify the code, he/she will add a easy print assertion to disclose the secrets and techniques (test traces #19 – #21)
import getpass import hvac VAULT_ADDR = 'http://127.0.0.1:8200' VAULT_TOKEN = getpass.getpass('Hashicorp Vault Token ID: ') shopper = hvac.Shopper() shopper = hvac.Shopper( url = VAULT_ADDR, token = VAULT_TOKEN ) response = shopper.secrets and techniques.kv.read_secret_version(path='ap') client_id = response['data']['data']['client_id'] client_secret = response['data']['data']['client_secret'] repo_token = response['data']['data']['repo_token'] print("Shopper ID: " + client_id) print("Shopper Secret: " + client_secret) print("Repo Token: " + repo_token)
hmmm… We have to forestall others from modifying the file… let’s see how Cython may also help with that.
1. For the sake of this POC, let’s depart the three print statements (traces #19 – #21). Ideally, these traces must be eliminated 😉
2. Make certain to have the “python3-devel” package deal put in (e.g., sudo yum set up python3-devel)
3. Set up Cython- sudo pip3 set up Cython
$ sudo pip3 set up Cython Gathering Cython Downloading https://recordsdata.pythonhosted.org/packages/40/67/36322cf0387cf65e6be80ba2d9a33db227ecbc624902f0cb2e4bf456261f/Cython-0.29.23-cp38-cp38-manylinux1_x86_64.whl (1.9MB) |████████████████████████████████| 1.9MB 23.3MB/s Putting in collected packages: Cython Efficiently put in Cython-0.29.23
4. Convert the python code into C code – cython hi there.py –embed (notice: add –embed flag to create a standalone program. If –embed is just not used the c code won’t have a foremost as it’ll imply to create a shared object reasonably than a standalone executable. After the next command is issued and executed, a c supply file hi there.c must be created in the identical listing)
$ cython hi there.py -o cython.c /usr/native/lib64/python3.8/site-packages/Cython/Compiler/Most important.py:369: FutureWarning: Cython directive 'language_level' not set, utilizing 2 for now (Py2). It will change in a later launch! File: /dwelling/ec2-user/hi there.py tree = Parsing.p_module(s, pxd, full_module_name)
5. Compile the c code into an executable – gcc `python3-config –cflags –ldflags` hi there.c -o hi there (notice: the embrace and library paths python should be specified. The execution of the next command ought to create an executable file hi there. this will likely be a distributable binary)
$ gcc `python3-config --cflags --ldflags` hi there.c -o hi there $ [NO OUTPUT]
6. Examine the folder content material – ls -rtl
$ ls -rtl complete 276 -rw-rw-r--. 1 ec2-user ec2-user 545 Jul 11 16:06 hi there.py -rw-rw-r--. 1 ec2-user ec2-user 139572 Jul 11 17:27 hi there.c -rwxrwxr-x. 1 ec2-user ec2-user 132312 Jul 11 17:29 hi there
7. Run the hi there script – ./hello (when requested, enter the “Root Token” from HashiCorp Vault Secret Supervisor article, step #4)
$ ./hi there Hashicorp Vault Token ID: [ --> Root Token: s.4Gl4TLJb1D82OWxxxxxxxxxx] Shopper ID: 123456789 Shopper Secret: 987654321 Repo Token: a1b2c3d4e5
8. View the hi there file content material – cat hi there (notice: file output was truncated)
$ cat hi there ELF>?J@@?@8 @'&@@@@@h??@?@@@HUHU 0]0]`0]`? ?HX[cBE??j??@?@ Cֻ?|??V?T?????@?@ P?td`P`P@`P@??Q?tdR?td0]0]`0]`??/lib64/ld-linux-x86-64.so.2GNU?GNUGNU?M?;>P??¸ܿ???ȡX?d! :? @h`(?E@F @b`5`L@??F@<J?J@/?h`Q?Ok@ea@L@libpython3.6m.so.1.0_ITM_deregisterTMCloneTable__gmon_start___ITM_registerTMCloneTablelibpthread.so.0libdl.so.2libutil.so.1libm.so.6_PyThreadState_UncheckedGetPyFrame_NewPyEval_EvalFrameExPyObject_GetAttrPyObject_CallPyThreadState_Get_Py_CheckRecursionLimit_Py_CheckRecursiveCallPyErr_OccurredPyExc_SystemErrorPyErr_SetStringPyObject_GetAttrString_Py_NoneStructPyDict_SetItemStringPyExc_AttributeErrorPyErr_ExceptionMatchesPyErr_ClearPyExc_ImportErrorPyModule_NewObjectPyModule_GetDictPyDict_GetItemWithErrorPyTuple_PackPyExc_KeyErrorPyErr_SetObjectPyExc_NameErrorPyErr_Format_PyDict_GetItem_KnownHashPyList_NewPyDict_NewPyImport_ImportModuleLevelObjectPyExc_RuntimeErrorPyOS_snprintfPy_GetVersionPyErr_WarnExPyFrame_TypePyTuple_NewPyBytes_FromStringAndSizePyUnicode_FromStringAndSizePyImport_AddModulePyObject_SetAttrStringPyUnicode_InternFromStringPyUnicode_DecodePyObject_HashPyObject_SetAttrPyImport_GetModuleDictPyDict_GetItemStringPyDict_SetItem_PyObject_GetDictPtrPyObject_Not_Py_FalseStruct_Py_TrueStructPyUnicode_FromStringPyFunction_TypePyEval_EvalCodeExPyCFunction_TypePyDict_TypePyObject_GetItemPyNumber_AddPyUnicode_FromFormatPyCode_NewPyMem_MallocPyMem_ReallocPyTraceBack_HerePyModuleDef_InitPyModule_TypePyType_IsSubtypePyModule_ExecDefPyErr_PrintPy_FinalizeExPyMem_RawFreePy_InitializePy_SetProgramNamePySys_SetArgvlibc.so.6setlocalembrtowcmbstowcs__stack_chk_failstrdupstrlenmallocstderrfwrite__libc_start_mainfree_edata__bss_start_end__pyx_module_is_main_helloPyInit_hello_IO_stdin_used__data_start__libc_csu_init__libc_csu_finiquiBC_2.D1?1?A?D9?%D??)șA???Hc?H??D9}?H??A????Hc?H??D9}???AVI??AUI??ATI??USH??????H??1?L??H??H???????H??H??tGH?D 1?H?L9?}I?T?H?H??H????1?H???????E H? I??u []AA]A^????H??H??I???O???L?%?9 ?H ???H A;AVAUATUSH?L???M??u $3H??H??L??A??H???&????p ?V??P A?$?H?=???? @?H?=?%?{?????t?1??59?} ??????@$H??u#?|???H??H??u?H??8 H?5?%H?8????H??[]AA]A^?AVE??AUI??ATI??H??US?y???H??t5H;]8 H??1?A??tH??L??L????????H? u)H?H???P0?H?08 ???H?8?]?????t?????1?[??]AA]A^???AUI??ATUSQ?$???H?PH??@ H??u H??@ ?"H9?tH?'8 H?%1?H?8?????H?-?B H??t H?E??H?5?%L??????I??H????H???A???I? $H??u wpercentL??L??H?s%?I?????xH???H? I?DL???P0H????H??????I??H????A?H? u H?H???P0ZH??[]AA]?USH??Q?-???H??H??ub?`???H??u[H?H?????t7?1??o???H??H??t7H??H?E6 H?8?e???H?
Final thoughts
This article attempts to find a solution to the problem. Cython seems like a promising option to consider. It is true that any user will have access to binaries that can be used to reverse engineer the application, but that’s going to take a good amount of time and work.
Disclaimers
- This article aims to cover the basic functionality of Cython.
- It’s also possible to combine the different approaches to provide an even more secure environment.
- Want to learn more about Cython? Please contact the Cross-Domain TAB team (mailto: xdc-amer-tab).
We’d love to hear what you think. Ask a question or leave a comment below.
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