(My)SQL Injection Attack [Tutorial]

Imagine you're baking a delicious batch of cookies, following your grandma's secret recipe. But then, a mischievous squirrel sneaks in and replaces a pinch of cinnamon with a dash of…mystery powder! That's kind of like an SQL injection (SQLi) attack. Hackers, like mischievous squirrels, exploit website vulnerabilities by sneaking malicious code into user input fields.

This "mystery powder" can trick the website's database (the oven) into baking something entirely different – maybe stealing your recipe, adding unwanted ingredients, or even burning the whole batch!

Thankfully, website bakers have special tools like data validation and locking cabinets to keep their ovens squirrel-proof and cookies safe. So, next time you trust a website with your information, remember: just like you wouldn't share your grandma's secret recipe with a squirrel, be careful what you input online. Keep your digital cookies safe from sneaky squirrels!

Let's crack open the hood of this website and peek at its inner workings, not to exploit weaknesses but to understand the delicate dance between data and security. Think of it as a friendly spelunking expedition through the code caves, unearthing the hidden tunnels and secret chambers that protect precious information. We'll be explorers, not exploiters, mapping the landscape of potential vulnerabilities so developers can equip their online fortresses with sturdier shields and clever traps (figuratively speaking, of course!). It's all about knowledge, not mischief, and like any good spelunker, we'll emerge with a newfound respect for the intricate systems that keep our digital world humming. So, grab your metaphorical helmet and headlamp, and let's embark on this educational adventure!

In this article, we will exploit this website for Dog Viewer. By default, without entering any ID, it displays Name: Saranac for ID: 1, which we can also get through this URL: https://web.ctflearn.com/web8/?id=1.

[How To] Unfollow Non-followers on Instagram

This tutorial walks you through the fastest and safest way to find and unfollow Instagram users who don't follow you back without logging in to third-party services, downloading browser extensions, or installing apps or software. 

Following the 15 steps mentioned in this article, you will end up with the accounts you follow but who don't follow you back. You need to go to each profile manually to unfollow them.

Step 1 - Go to https://www.instagram.com/ and log in with your credentials.

Step 2 - Go to "Profile" (button with your display picture) >> "Settings and privacy" (button with the gear icon) >> "See more in Accounts Center."

Simplify Rational Numbers in Python

The real number system: rational numbers (with natural, whole, and integers nested inside) alongside irrational numbers.

What Is a Rational Number?

A rational number is any number that can be expressed as a fraction of two integers, where the numerator is a whole number and the denominator is a non-zero integer. The decimal form of a rational number either ends (terminates) or repeats infinitely. ^{[1, 2, 3, 4]}

Key Characteristics and Forms

Rational numbers encompass a wide variety of numbers, which can always be categorized into these four main forms:

• Integers: All whole numbers, both positive and negative, are rational because they can be written as a fraction over 1 (e.g., 5 = 5/1, -3 = -3/1).
• Fractions: Any standard or mixed fraction where the top and bottom are integers (with a denominator not equal to 0) is rational (e.g., 3/4, 2 1/2).
• Terminating Decimals: Decimals that eventually stop are rational because they can be converted into fractions (e.g., 0.75 = 3/4).
• Repeating Decimals: Decimals that go on forever in a predictable, repeating pattern are rational and can be converted into fractions (e.g., 0.333... = 1/3). ^{[3, 4, 6]}

Non-Examples (Irrational Numbers)

If a number cannot be written as a fraction, and its decimal portion neither terminates nor repeats, it is considered irrational.

• Examples: π (Pi), the square root of a non-perfect square (e.g., √2), or Euler's number (e). ^{[1, 2, 4, 6, 7]}

References

1. Wikipedia: Rational number
2. YouTube: What is a rational number
3. Mathnasium: What is a rational number
4. Math is Fun: Rational Numbers
5. YouTube Shorts: Rational numbers
6. Mathnasium: Rational number (term)
7. Mometrix: Rational Numbers

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How the Code Works

The notebook below converts a floating-point number into an exact fraction, and shows why the obvious approach can be surprising. It uses Python's built-in fractions.Fraction together with SymPy's Rational and nsimplify.

• Imports: from fractions import Fraction and from sympy import Rational, nsimplify bring in both the standard-library fraction type and the symbolic-math tools.
• Fraction(1.1) and Fraction.from_float(1.1): these return the exact value the computer actually stores for 1.1. Because 1.1 cannot be represented exactly in binary floating point, the result is a long, unexpected fraction rather than 11/10.
• Rational(1.1): SymPy's Rational applied to a float behaves the same way, reflecting the exact binary value of the float.
• nsimplify(1.1): nsimplify works backwards from the float to find the simple rational a human most likely meant, recovering 11/10.
• to_frational(x): a small helper that prints both Fraction(x) and nsimplify(x) side by side, so you can compare the literal floating-point fraction against the cleaned-up rational for any input.

The takeaway: converting a float straight to a fraction preserves the floating-point rounding error, while nsimplify recovers the intended simple fraction.

In [1]:

from fractions import Fraction
from sympy import Rational, nsimplify

In [2]:

Fraction.from_float(1.1)

Out[2]:

Fraction(2476979795053773, 2251799813685248)

In [3]:

Fraction(1.1)

Out[3]:

Fraction(2476979795053773, 2251799813685248)

In [4]:

Rational(1.1)

Out[4]:

$\displaystyle \frac{2476979795053773}{2251799813685248}$

In [5]:

nsimplify(1.1)

Out[5]:

$\displaystyle \frac{11}{10}$

In [6]:

def to_frational(x):
  print(Fraction(x))
  print(nsimplify(x))
  print()

In [7]:

vals = [0.0,
        1.2879011017187576,
        2.5905203907920316e-16,
        -0.4714045207910316,
        1.4802973661668753e-16,
        0.3450920601366943]

In [8]:

for v in vals:
  to_frational(v)

0
0

725023865223831/562949953421312
32197527542969/25000000000000

2627099782632789/10141204801825835211973625643008
259052039079203/1000000000000000000000000000000

-8492068896701029/18014398509481984
-sqrt(2)/3

6004799503160661/40564819207303340847894502572032
9251858538543/62500000000000000000000000000

6216625893760533/18014398509481984
172546030068347/500000000000000