On 26th March 14.50 KST, specialist sites on North Korea such as Free NK Radio, NK Intellectuals Solidarity and Daily NK went down. It appears that they have suffered from a series of hacking attempts.
This follows in the wake of major South Korean media sites having been hacked by an unknown source.
Last month, there was a hacking attempt on New Focus, in which three days worth of data were deleted. After the incident, the site stepped up security through consulting with a specialist firm and upgrading to secure servers.