Citrix Systems, a networking software giant, has disclosed that malicious hackers were inside its networks for five months between 2018 and 2019, accessing personal and financial data on employees, contractors, and others. The hackers gained access using a technique called password spraying, which attempts to access a large number of employee accounts using common passwords. The breach was initially disclosed in March 2019, but new details have emerged, including the duration of the breach and the types of data accessed. The incident has raised concerns about the security of Citrix's products and services, which are used by hundreds of thousands of clients worldwide.