WannaCry ransomware attack

The WannaCry ransomware attack was a worldwide cyberattack in May 2017 by the WannaCry ransomware cryptoworm, which targeted computers running the Microsoft Windows operating system by encrypting data and demanding ransom payments in the form of bitcoin cryptocurrency. It was propagated using EternalBlue, an exploit developed by the United States National Security Agency (NSA) for Microsoft Windows systems. EternalBlue was stolen and leaked by a group called The Shadow Brokers (TSB) a month prior to the attack. While Microsoft had released patches previously to close the exploit, much of WannaCry's spread was from organizations that had not applied these patches, or were using older Windows systems that were past their end of life. These patches were imperative to cyber security, but many organizations did not apply them, citing a need for 24/7 operation, the risk of formerly working applications breaking because of the changes, lack of personnel or time to install them, or other reasons.

The attack began at 07:44 UTC on 12 May 2017 and was halted a few hours later at 15:03 UTC by the registration of a kill switch discovered by Marcus Hutchins. The kill switch prevented already infected computers from being encrypted or further spreading WannaCry. The attack was estimated to have affected more than 300,000 computers across 150 countries, with total damages ranging from hundreds of millions to billions of dollars. At the time, security experts believed from preliminary evaluation of the worm that the attack originated from North Korea or agencies working for the country. In December 2017, the United States and United Kingdom formally asserted that North Korea was behind the attack, although North Korea has denied any involvement with the attack.

A new variant of WannaCry forced Taiwan Semiconductor Manufacturing Company (TSMC) to temporarily shut down several of its chip-fabrication factories in August 2018. The worm spread onto 10,000 machines in TSMC's most advanced facilities.

WannaCry is a ransomware crypto worm, which targets computers running the Microsoft Windows operating system by encrypting (locking) data and demanding ransom payments in the Bitcoin cryptocurrency. The worm is also known as WannaCrypt, Wana Decrypt0r 2.0, WanaCrypt0r 2.0, and Wanna Decryptor. It is considered a network worm because it also includes a transport mechanism to automatically spread itself. This transport code scans for vulnerable systems, then uses the EternalBlue exploit to gain access, and the DoublePulsar tool to install and execute a copy of itself. WannaCry versions 0, 1 and 2 were created using Microsoft Visual C++ 6.0.

EternalBlue is an exploit of Microsoft's implementation of their Server Message Block (SMB) protocol released by The Shadow Brokers. Much of the attention and comment around the event was occasioned by the fact that the U.S. National Security Agency (NSA) (from whom the exploit was likely stolen) had already discovered the vulnerability, but used it to create an exploit for its own offensive work, rather than report it to Microsoft. Microsoft eventually discovered the vulnerability, and on Tuesday, 14 March 2017, they issued security bulletin MS17-010, which detailed the flaw and announced that patches had been released for all Windows versions that were currently supported at that time, these being Windows Vista, Windows 7, Windows 8.1, Windows 10, Windows Server 2008, Windows Server 2008 R2, Windows Server 2012, Windows Server 2012 R2, and Windows Server 2016.

DoublePulsar is a backdoor tool, also released by The Shadow Brokers on 14 April 2017. Starting from 21 April 2017, security researchers reported that there were tens of thousands of computers with the DoublePulsar backdoor installed. By 25 April, reports estimated that the number of infected computers could be up to several hundred thousand, with numbers increasing every day. The WannaCry code can take advantage of any existing DoublePulsar infection, or installs it itself. On 9 May 2017, private cybersecurity company RiskSense released code on GitHub with the stated purpose of allowing legal white hat penetration testers to test the CVE-2017-0144 exploit on unpatched systems.

When executed, the WannaCry malware first checks the kill switch domain name (iuqerfsodp9ifjaposdfjhgosurijfaewrwergwea.com); if it is not found, then the ransomware encrypts the computer's data, then attempts to exploit the SMB vulnerability to spread out to random computers on the Internet, and laterally to computers on the same network. On the local system, the WannaCry executable file extracts and installs binary and configuration files from its resource section. It also hides the extracted directory, modifies security descriptors, creates an encryption key, deletes shadow copies, and so on. As with other modern ransomware, the payload displays a message informing the user that their files have been encrypted, and demands a payment of around US$300 in bitcoin within three days, or US$600 within seven days, warning that "you have not so enough time. [sic]" Three hardcoded bitcoin addresses, or wallets, are used to receive the payments of victims. As with all such wallets, their transactions and balances are publicly accessible even though the cryptocurrency wallet owners remain unknown.

Several organizations released detailed technical write-ups of the malware, including a senior security analyst at RiskSense, Microsoft, Cisco, Malwarebytes, Symantec, and McAfee.