Shadowrun: Zero Day Exploit

IRL a Zero-Day also sometimes written as 0-Day, is a previously undiscovered and undocumented vulerability in a piece of hardware or software which can be exploited by a hacker to remotely execute code often for malicious purposes. Since this is unknown at the time they are used, a person has zero days to prepare for it.

In terms of Shadowrun, this means that it can be an item used during a hacking attempt to grant an automatic success to that attempt regardless of skill. But there are some caveats:

IRL Zero-Day exploits are unique to a specific piece or series of hardware/software only. It doesn't work on everything.

So in Shadowrun a Zero-Day exploit will only work on systems that match the stats of the exploit. If the exploit stats don't match the stats of the targeted system, it will not work. The player will be unable to use it for that attempt.

IRL when a Zero-Day is used, it has a chance of being discovered. Once it is discovered, it will often get reported to the hardware/software developers and patched. Once that happens, it becomes useless against any system that installs the patch.

So in Shadowrun, the Zero-Day exploit only grants an automatic success once. Afterwards it only acts as a buff to your hacking skill for systems that match the exploit stats. Once you fail an attempt while using it, this item is consumed and you lose that buff since it is now considered patched.

IRL Zero-Day exploits are extremely difficult to find and are thus extremely valuable. Finding them requires days to months of maticulous, systematic probing, analysis, and reverse engineering of a particular piece of hardware/software. And there is a chance that none can be found. So when one is found, it can be reported to the vendor for a potential reward, or sold to a broker for a shit ton of money. Zero-Day brokers then auction these exploits off on the dark net and hackers are willing to pay big money for them.

In Shadowrun, it will be extremely unlikely to be able to discover one of these on your own without really extremely high skills revelent to whatever it is you are trying to find one in. Plus you would require the proper facilities and equipment depending on what you are trying to discover one in. So a player's best bet would be to buy them off of a broker in them or get/steal them from someone who has some. If you happen to have one on hand, you could turn it in to the developer of the system it targets for a possible reward, or sell/trade it with someone.

The GM can use Zero-Day exploits to handwave being able to hack into systems that are practically hack proof.