Q.Wanna Cry malware/ransomeware?
Ans It is basically a malware or vulnerability that attacks using "smb" network service on old systems like windows xp,windows 7. And one of the most fascinating thing about this malware is that it encypts your data.
"WannaCry (or WannaCrypt,[3] WanaCrypt0r 2.0,[4][5] Wanna Decryptor[6]) is a ransomware program targeting Microsoft Windows operating system.[7] On Friday, 12 May 2017, a large cyber-attack using it was launched, infecting more than 230,000 computers in 150 countries, demanding ransom payments in the cryptocurrency bitcoin in 28 languages.[8] The attack spreads by multiple methods, including phishing emails[9] and on unpatched systems as a computer worm. The attack has been described by Europol as unprecedented in scale.[10]
The attack affected Telefónica and several other large companies in Spain, as well as parts of Britain's National Health Service (NHS),[11] FedEx, Deutsche Bahn and LATAM Airlines.[12][13][14][15] Other targets in at least 99 countries were also reported to have been attacked around the same time.[16][17]
WannaCry is believed to use the EternalBlue exploit, which was developed by the U.S. National Security Agency (NSA)[18][19] to attack computers running Microsoft Windows operating systems.[5][20] Although a patch to remove the underlying vulnerability for supported systems (Windows Vista and later operating systems) had been issued on 14 March 2017,[21] delays in applying security updates and lack of support by Microsoft of legacy versions of Windows left many users vulnerable.[22] Due to the scale of the attack, to deal with the unsupported Windows systems and in an effort to contain the spread of the ransomware, Microsoft has taken the unusual step of releasing updates for all older unsupported operating systems from Windows XP onwards.[3][23]"

The core of the issue is Microsoft’s tiered support system. The vulnerability targeted last week doesn’t exist in systems released since Windows 8 (which introduced SMBv3), so the main targets were Windows 7 and Windows XP. Windows 7 users are still receiving patches, but XP has been unsupported since April 2014. Users can still pay for updates through Microsoft’s Custom Support service, but the company isn’t deploying patches publicly, even though the system is still widely used in Africa and Asia. The company published an emergency XP patch over the weekend to protect against the ransomware, but it was too late for NHS and countless other victims.