I'll preface this by saying that I can't support this with a source, so take it with a grain of salt. An acquaintance of mine knew someone who worked in that German embassy. Apparently, the extreme isolation of North Korea also made it extremely difficult to have any kind of opsec inside the embassy. Since anything could only be brought in through diplomatic pouches it created an attack vector of one.
A few days after said person had a meeting in the German equivalent of a scif, there was a meeting with North Korean officials. One official let something slip, which meant a bug had somehow gotten into the scif. He didn't say anything about what the consequences were, just that one should not underestimate the North Koreans.