On Tuesday, The Foundation for Internet Domain Registration (.NL) in the Netherlands (SIDN) was compromised and some malicious files were uploaded to their server by hackers. In another cyber attack on Tuesday, several Belgium websites was also got defaced by another group of hackers. The hackers were able to infiltrate and modify a DNS server, pointing all of the websites to a single website displaying the deface message. DNS.be said in a statement that user data or the registration platform had not been compromised.
Source: https://thehackernews.com/2013/07/thousands-of-websites-defaced-after.html