Is black-hat hacking haram?

Question

I made a virus that mines Ethereum silently in the background. You can already see that this is just for money. But I plan on paying the victim back through donations. My target is some gaming station in my country, and they have really high-end gaming PCs. I noticed that they allow us to plug in our pendrive, so I just saw this as an opportunity.

I've talked this out with my friends, but they all say it's haram without the slightest idea what Ethereum mining actually is, so please don't answer if you don't know anything about cryptocurrency mining. Some of my friends agree on this idea, but they say that I should use the money for good purposes, like charity, not just buying games on Steam.

All I want is an expert's opinion on this. Is this haram, halal, or in between?

Summary:

1. I plan to use 50% of the money for donating to charity agencies
2. I plan to pay back the gaming station after I'm done reaching my goal

Answer 1

Cryptocurrency mining entails heavy use of computing hardware (GPUs), which results in electricity costs. Moreover, you're describing the use of the services of a rental business without paying the rent. Consequently, if a scholar would answer this specific question, I would expect them to declare it haram.

The closest fatwa I found describes the use of someone's Wi-Fi without their permission. In this context, a scholar is quoted as saying:

“If we were to determine if it was religiously forbidden or not, we have to look at the privacy and usage laws, and if the extra usage would result in additional expenses for the neighbour.”

But hacking into a secured Wi-Fi account “is not permissible at all. It is like crossing the property rights of others”.
_{Dubai’s Islamic authority issues fatwa on stealing Wi-Fi, The National}

Moreover, the fact that you intend to pay back the gaming station indicates you feel you are gaining possession of something that belongs to them (and hence feel a need to "pay back" something). (And are you paying back the normal rental price of the machines, regardless of whether or not the mining attempt is successful?)

Generally, Muslims are required to obey the "law of the land":

Muslims are generally obliged to abide by the laws of the land and the country they live in...
_{DarulIftaa.com}

Many countries have anti-hacking (cybercrime) laws. Let's look at Sri Lanka, which is listed on the OP's profile.

Any person who, intentionally and without lawful authority causes a computer to perform any function knowing or having reason to believe that such function will result in unauthorised modification or damage or potential damage to any computer or computer system or computer programme shall be guilty of an offence and shall on conviction be liable to a fine not exceeding three hundred thousand rupees or to imprisonment of either description for as term which may extend to five years or to both such fine and imprisonment.
_{Computer Crime Act, no. 24, 2007}

It's reasonable to conclude the proposed scheme is illegal in Sri Lanka (although, I'm not a lawyer).

In addition:

• Islam discourages deception (see IslamReligion for a survey). There's various ahadith to this effect, such as Allah's Messenger forbade Najsh (Sahih al-Bukhari 2142).

• A vigilant administrator would detect the heavy use of these machines during idle time, and take action against it.