In a statement on Friday, the N.H.S. said its inquiry into the attack was in its early phases but that “at this stage we do not have any evidence that patient data has been accessed.” The NHS used the old XP on its computers. The N.H.S., founded after World War II, employs 1.6 million people with a combined budget of £140 billion, making it one of the largest employers in the world. As the attack unfolded on Friday, N.H.S. officials struggled to get a handle on the problem, but urged patients who had emergencies to go to hospitals or seek care as they normally would. This attack, believed with Wanna Decryptor malware, was not specifically targeted at the NHS and is affecting organizations from across a range of sectors. Even if the support for Windows XP was previously discontinued, Microsoft released now a patch for the outdated systems.