D385 Pre-Assessment (All Correct)

What is the primary defense against log injection attacks?

Sanitize outbound log messages

import logging

import sys

import logging

import sys

#log division by zero error to the log, the output is printed to the screen

def divideByZeroError(dividend, divisor):

logging.basicConfig(stream=sys.stdout,format='%(levelname)s:%(message)s')

try:

quotient = dividend/divisor

print (quotient)

except Exception as e:

#logging error here, use str(e) as part of the output

if __name__ == '__main__':

dividend = int(input())

divisor = int(input())

divideByZeroError(dividend,divisor)

logging.error("The exception that occured is: %s", str(e))

An attacker exploits a cross-site scripting vulnerability.

Access the user's data

Which Python function is prone to a potential code injection attack?

eval()

What are two common defensive coding techniques?

Check functional and preconditions and postconditions

# unit test case

import unittest

def multiply_numbers(x, y):

#add your code here

return x * y

# add your code here

class TestForNone(unittest.TestCase):

def test_when_a_is_null(self):

try:

self.assertIsNone(multiply_numbers(5, None))

except AssertionError as msg:

print(msg)

if __name__ == '__main__':

unittest.main()

if x is None:

print("x is a null value")

return y

elif y is None:

print("y is a null value")

return x

else:

return x * y

Which package is meant for internal use by Python for regression testing?

test

from string import Template

CONFIG = {

"API_KEY": "'you've just exposed your secret_key'"

}

class User:

name = ""

email = ""

def __init__(self, name, email):

self.name = name

self.email = email

def __str__(self):

return self.name

if __name__ == '__main__':

name = input()

email = input()

user = User(name, email)

# FIXME: Here is where you want to use the template class

print(f"The secret is {user.__init__.__globals__['CONFIG']['API_KEY']}")

t = Template("Hello, my name is $n.")

print(t.substitute(n=user.name))

import time

class Limiter:

def __init__(self, rate, per):

self.rate = rate

self.per = per

self.bucket = rate

self.last_check = time.time()

def limit(self, callback_fn):

current = time.time()

time_passed = current - self.last_check

self.last_check = current

# Finish line 18 by writing an expression that determines the value of the bucket

# Use the following variables in your expression: time_passed, self.bucket, self.rate, and self.per

bucket = # Insert your expression here

if (bucket > self.rate):

self.bucket = self.rate

if (bucket < 1):

pass

else:

callback_fn()

self.bucket = bucket - 1

bucket = self.bucket + (time_passed * self.rate / self.per)

def CelciusToFahrenheit(Temperature):

#insert assert statement for, "Colder than zero degrees Celsius!"

return ((Temperature*9)/5)+32

if __name__ == '__main__':

Temperature = int(input())

try:

print(CelciusToFahrenheit(Temperature))

except AssertionError as msg:

print(msg)

assert Temperature >= 0, "Colder than zero degrees Celsius!"

# verify we only have digits

def check_numeric_value(wg_int):

return isinstance(wg_int, int)

#return true if numeric value is an integer, else return false.

#Hint: use isinstance function

# verify if the string is null

def check_null_string (wg_string):

# check if wg_string is not null return true else return false

if __name__ == '__main__':

wg_string = "I like dogs." # use keyword None to test

wg_int = 12345

print(check_null_string (wg_string))

print(check_numeric_value(wg_int))

return isinstance(wg_int, int)

return wg_string is not None

def hash_password(pwd):

# encode password string to bytes

enc_pwd = pwd.encode()

# call the sha256(...) function returns a hash object

d = hashlib.sha256(enc_pwd)

# generate binary hash of password string in hexidecimal

hash = d.digest()

return hash

if __name__ == '__main__':

pwd = input()

print(hash_password(pwd))

d = hashlib.sha3_256(enc_pwd)

hash = d.hexdigest()

from generate_key import generate_key

from deserialize import deserialize

from serialize import serialize

def safe_deserialize(key, serialized_data):

new_key = '' # replace the empty string with a newly generated key

try:

if key == new_key:

return # return deserialized data when validation passes

else:

raise Exception('New key does not match old key')

except Exception as error:

print('Error:', error)

return False

# Example usage

grades = {'Alice': 89, 'Bob': 72, 'Charles': 87}

serialized_data = serialize(grades)

deserialized_data = safe_deserialize(generate_key(serialized_data), serialized_data)

new_key = generate_key(serialized_data)

return deserialize(serialized_data)

isValidNumber = False

while not isValidNumber:

try:

pickedNumber = int(input('Pick a number from 1 to 10'))

if pickedNumber >= 1 and pickedNumber <= 10:

isValidNumber = True

except:

print('You must enter a valid number from 1 to 10')

print('You picked the number ' + str(pickedNumber))

Type and range check

import requests

urls = open("websites.txt", "r")

for url in urls:

url = url.strip()

req = requests.get(url)

print (url, 'report😂

try:transport_security = req.headers['Strict-Transport-Security']except:print ('HSTS header not set properly')

Man-in-the-middle

#check if the zipcode input is numeric

if __name__ == '__main__':

zipCode = input()

try:

#check that zip code is an integer value

print(f'Your zip code is {zipCode}.')

except:

print('Please use numeric digits for the zip code.')

zipCode = int(zipCode)

#check if the length of the password is at least 8 characters

if __name__ == '__main__':

password = input()

#write an if / else statement to evaluate passwords length

if(len(password) >= 8):

print("Your password is long enough.")

else:

print("Your password is too short.")

#check if the input range is between 1 and 10 for the range validation check

if __name__ == '__main__':

r = range(1,10)

num = int(input())

# create conditional statement for range check here

r = range(1,11)

num = int(input())

if num in r:

print("The number input is in the range from 1 and 10.")

else:

print("The number input is not in the range from 1 and 10.")

A security analyst has noticed a vulnerability in which an attacker took over multiple users' accounts.

Which vulnerability did the security analyst encounter?

Broken access control

When creating a new user, an administrator must submit the following fields to an API endpoint:

Name

Email Address

Password

IsAdmin

What is the best way to ensure the API is protected against privilege escalation?

Implement resource and field-level access control

Which method is used for a SQL injection attack?

Exploiting query parameters

import hashlib

from Crypto.Cipher import AES

from base64 import b64encode, b64decode

import os

class AESCipher(object):

def __init__(self, key):

self.block_size = AES.block_size

self.key = hashlib.sha256(key.encode()).digest()

def encrypt(self, plain_text):

plain_text = self.__pad(plain_text)

counter = self.block_size.to_bytes(self.block_size, "big")

cipher = AES.new(self.key, AES.MODE_CTR, counter=lambda: counter)

#FIX ME: encrypted_text = ?

return b64encode(counter + encrypted_text).decode("utf-8")

def __pad(self, plain_text):

number_of_bytes_to_pad = self.block_size - len(plain_text) % self.block_size

ascii_string = chr(number_of_bytes_to_pad)

padding_str = number_of_bytes_to_pad * ascii_string

padded_plain_text = plain_text + padding_str

return padded_plain_text

if __name__ == '__main__':

msg = input("Enter message: ")

cipher = AESCipher(msg)

#Test the message size

msg = msg*10

print(cipher.encrypt(msg))

encrypted_text = cipher.encrypt(plain_text)

import os

import stat

def admin(filename, admin):

return admin

def user(filename, user):

return user

def grant_permission(name_list, filename):

# FIXME

os.chmod(filename, stat.S_IRWXU)

check_permission(filename)

def check_permission(filename):

# Check if file path exists

path1 = os.access(filename, os.F_OK)

print("The path exists:", path1)

# Check if User has Read Access

path2 = os.access(filename, os.R_OK)

print("Access to read the file:", path2)

# Check if User has Write Access

path3 = os.access(filename, os.W_OK)

print("Access to write the file:", path3)

# Check if User has Execute Permission

path4 = os.access(filename, os.X_OK)

print("Check if path can be executed:", path4)

if os.access(filename, os.R_OK):

# open txt file as file

with open(filename) as file:

file.read()

else:

# in case can't access the file

print("Cannot access the file")

with open("output_file.txt", 'w') as f:

if os.access(filename, os.W_OK):

f.write("I have write privilege.\n")

if __name__ == '__main__':

filename = input()

name = input()

k = []

res

if result:

os.chmod(filename, stat.S_IRWXU)

else:

os.chmod(filename, stat.S_IRUSR | stat.S_IRGRP | stat.S_IROTH)

def authorizeAdmin(usr):

assert isinstance(usr, list) and usr != [], "No user found"

assert 'admin' in usr, "No admin found."

print("You are granted full access to the application.")

If __name__ == '__main__':

authorizeAdmin(['user'])

AssertionError: No admin found

#Simulated auhorization code

ownerID = 4567

def ShowData():

print("This is the user data")

def Redirect():

print("Redirecting to homepage")

def GetUserID():

return 1234

if(not GetUserID() == ownerID): # this is just a simulation, this line is typically !$_GET['userID'] === object.ownerID

print( "You are not allowed to view this data")

Redirect()

ShowData()

if(not GetUserID() == ownerID): # this is just a simulation, this line is typically !$_GET['userID'] === object.ownerID

print( "You are not allowed to view this data")

Redirect()

else:

ShowData()

What does cross-origin resource sharing (CORS) allow users to do?

Override same starting policy for specific resources

Which protocol caches a token after it has been acquired?

MSAL

import requests

url = 'https://website.com/'

# Get request

result = requests.get(url)

# Print request

print(result.content.decode())

403

import requests

url = 'https://api.github.com/invalid'

try:

request_response = requests.get(url)

# If the response was successful, no Exception will be raised

request_response.raise_for_status()

except Exception as err:

print(f'Other error occurred: {err}')

else:

print('Success!')

404 - Not Found

Which response method, when sent a request, returns information about the server's response and is delivered back to the console?

response.content

Status Codes

- 200 = OK

- 201 = CREATED

- 400 = BAD REQUEST

- 401 = UNAUTHORIZED

- 403 = FORBIDDEN

- 404 = NOT FOUND

- 405 = METHOD NOT ALLOWED

- 500 = INTERNAL SERVER ERROR

200

Ok

201

Created

400

Bad Request

401

Unauthorized

403

Forbidden

404

Not Found

405

Method Not Allowed

500

Internal Server Error