Master, what do you think Itakura was forced to create for the BO? What kind of software could it be?
Itakura Software Theory
I think that Itakura's software is a virus software that can erase any data you want on a mass scale from everywhere that is connected to the internet.
This idea stems from the Black Organization's shown interest and usage of the throroughly-introduced Night Baron Virus in File 72-77.
During Tequila case (File 116), they were shown to be looking for programmers, even after Vermouth having already force-hired Itakura into creating the software 1 year ago for her own agenda (File 380).
After that, we had Haibara's intro (File 181) that revealed that they got ahold of the Night Baron Virus, that they used as a trap to delete sensitive data that is opened on unauthorized computers.
Gosho replied to a fan question saying that one could have figured out what Itakura software's purpose was if one properly read and understood the story (SDB 60+).
Night Baron virus is our only and best basis for guessing at what kind of software they were aiming to create when looking for the best programmers in the world, since it's the only program/software we have seen them associated with. So the best conclusion to arrive at is that Itakura's software was meant to be something akin to erasing data, but on a larger scale. If the BO got ahold of such a software, then they could truly harm humanity (as Itakura mentioned in File 380), since digital data is heavily relied on in society (economy, hospitals, etc) and erasure of it on a mass scale could mean life and death for many people.
This potential purpose for the software fits perfectly with the hinted personal agenda that Vermouth had when she force-hired Itakura.
During Mystery Train (File 823), Yukiko hit the mark while speculating in front of Vermouth regarding the purpose of the software when she asked her if it had something to do with why she is hiding Shinichi and Sherry's shrinking.
If Vermouth's reason for hiding the shrinking is to hide any progress to the foolish research in order to stop the Boss from achieving his goal, then using a software that can erase the entire saved research data, as well as any research data related to it from the whole world on a mass scale would benefit her immensely.
This would also be a betrayal against the boss on the highest level that it makes sense why Vermouth hurriedly hung up on Itakura as the boss was approaching with his cat (File 398).
The explanation behind the cat's cry was according SDB Black+, that speculates that "a cat alone doesn't feel like the reason Vermouth would hang up. But maybe someone hugging a cat was approaching her. And maybe that someone was Karasuma..."
