Just a few bytes of code, your computer will crash!

One of the best programming jokes in history is: Why do programmers die in the bathroom? Because the shampoo bottle says "knead foam, rinse, repeat."

In fact, this is an endless cycle. Obviously, well-organized programmers "repeated" this cycle of instructions until they die. Think this is ridiculous? But computers have been brought into this cycle for years.

In fact, this is a classic "fork bomb" attack. Although a fork bomb may be only a few characters long, it can allow computers to use up their resources and can no longer do anything else.

In some computer languages, this small character set can define a meaningless function and then require the computer to repeat it. The computer will not ask why. It will only do so. However, don't try to run this code at home because it can slow down your computer and may even cause your computer to crash.

Researchers at the University of Cambridge estimated in 2013 that computer leaks will cost the global economy approximately $312 billion a year. Even small loopholes can cause huge losses. For example, a line of error code may make the warship unable to travel. But how could such a code with very few bytes cause such a large loss?

Ben Liblit, a computer scientist at the University of Wisconsin, said: "The computer will follow the instructions received, what you give it, and what it will do. The computer does not rely on common sense."

Why is there an infinite loop? Ben Liblit stated that because many times iterative execution of a task can do many things that humans find bored and take time, saving human time, such as editing a large list of names, and capitalizing the first letter of all names. There is no hard and fast rule for the number of iterations of the loop. Theoretically, as long as the computer can cope, the loop can be repeated forever.

The first recorded fork bomb dates back to 1978. Just like the above example, the small program called wabbit does its own thing.

A code like this (a type of malware) will disguise itself as an ordinary file and enter the victim's computer as an e-mail attachment. If the victim downloads and runs this file, the fork bomb that was triggered by the wait will be detonated.

Mikko Hypponen, F-Secure's cybersecurity expert, also said that hackers can also allow victims to unzip more internal files when opening a compressed folder. This is called a zip bomb, and one of the famous compression bombs is only 42 bytes before decompression. It can fill up the victim's hard drive, unzip the file's virus killing software, and exhaust the computer's memory.

In 2014, a computer software used to encrypt network-sensitive data was found to have serious flaws. The flaw, called Heartbleed, allows an attacker to steal private data, such as passwords or credit card information. Alan Woodward of the University of Surrey in the United Kingdom stated that the procedure to execute this attack is only 4 bytes.

For malicious hackers, it is useful to use very few bytes to achieve destructive operations. For example, the famous "Twitter virus" in 2010 can open a pop-up window. Users simply slide the mouse over the tweets on twitter.com and the browser will pop up a window, even if the official White House Twitter was once also affected.

Steve Lord, Mandalorian's cybersecurity expert, said that one vulnerability he recently researched could insert malicious code into a single packet. This is a very complicated loophole that allows attackers to break through the secure connection of a virtual private network (VPN).

The shortest code that causes damage should be "0". Dividing by 0 creates an indefinite number that the computer cannot handle.

Steve Lord stated that this is exactly what happened on the Yorkshire warship in September 1997. A program on the warship was incorrectly divided by 0. As a result, the entire warship was completely shut down during cruising and had to be towed back to the port for maintenance.

Steve Lord said: "Thank goodness, this didn't happen in the battle." He also mentioned a malicious software called Tiny Banker, which infected the victim's browser whenever the victim landed on his online banking account. Tiny Banker will copy this information. It is only 20,000 bytes in size but it infects thousands of computer systems around the world. "In the Windows program, Tiny Banker is really small."

The above example does not mean that the computer itself is full of loopholes, but it does prove that it is very challenging to protect computer systems from malicious attacks. Steve Lord even said that some mistakes are quite "beautiful", but the US Navy may not agree with this.

As Ben Liblit said, whether the consequences of execution are favorable or harmful, the computer will follow the instructions meticulously. He said: "Computers can do useful things and they can do destructive things."

In any case, at least in most cases, you can restart your computer to solve the problem. After all, "restart and try" is a philosophy of life that is as easy to use as "do not divide."

Via bbc