13 May 2017

WannaCry Ransomware used in large scale international attacks

[This initial advisory is being updated. Current version is here.] What's happening

Systems affected

Earlier today a massive international ransomware campaign hit computer systems of private companies and public organisations around the world. This incident is being reported as the largest ransomware campaign to date. The Ransomware in question has been identified as a variant of ransomware known as WannaCry (also known as 'Wana Decrypt0r,' 'WannaCryptor' or 'WCRY'), because the encrypted files extension is .wcry. Like other ransomware, WannaCry also blocks access to a computer or its files and demands money to unlock it. Early reports were that the ransom demanded was around $430NZD, though this has allegedly doubled over the past few hours.

We’re learning more about this particular attack as it unfolds. At this point, CERT NZ understands that the initial attack vector is likely a phishing email with either a malicious attachment or link. The exploit penetrates into machines running unpatched versions of Windows (XP through 2008 R2) by exploiting flaws in Microsoft Windows SMB Server. Once a single computer in a network is infected with WannaCry, the program looks for other vulnerable computers on the network and infects them as well.

This ransomware exploits a Windows vulnerability known as EternalBlue, which was released by the Shadow Brokers hacking group over a month ago. Microsoft released a patch for the vulnerability in March (MS17-010).

What to do

Prevention

The information we have shows that this ransomware's initial infection is spread through emails. There is conflicting information about the details and attributes of the initial emails however they are reported to contain either links or attachments. Be careful when opening emails and clicking on links – read our phishing information to know what to look out for. These emails could be from anyone, including an email address you’re familiar with.

Make sure you have backed up your system and files stored securely, off-network.

Make sure you have patched your system. Organisations using any Windows system between XP to 2008 R2 should ensure that mitigations are in place, particularly the MS17-010 Microsoft patch. If you’re not patched, consider disabling SMBv1 (this will stop some file sharing). There is no patch available for XP & 2003, these OS’s need to be either turned off or have SMBv1 disabled.

It is also important to ensure that staff are aware of this campaign, and reminded to be extremely vigilant with incoming emails containing links and attachments.

More information

The details on this release are relatively new and more information is coming to light constantly. For organisations that require further support or more specified advice, please log an incident on our website at cert.govt.nz. Similarly, if you have been compromised with this ransomware, please contact CERT NZ.

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