I've been reading Thirteen Years at the Russian Court by Pierre Gilliard, who was a tutor to Tsar Nicholas II's children. He talks about how during the war Germany set about trying to cause unrest by spreading propaganda within Russia. Here are some excerpts:

At Berlin the authorities now knew that Nicholas II would stand by his allies to the bitter end, and that all attempts at a rapprochement would be broken against his unswerving determination to continue the war at any cost. They also knew that the Tsar was the sole bond between the different parties in the Empire, and that once it was removed no organised power would be capable of averting dismemberment and anarchy. The German General Staff therefore devoted itself unceasingly to ruin the prestige of the monarchy and bring about the downfall of the Tsar. To attain that object the essential step was to compromise the Tsar in the eyes of his people and his allies. Germany had in Russia many sources of intelligence and powerful means of action, and she devoted herself to spreading the idea that the Tsar was thinking of liquidating the war and making a separate peace.

...

I have explained above that in the autumn of 1915 the Berlin Government had realised that they could never overthrow Russia as long as she stood united round her Tsar, and that from that moment her one idea had been to provoke a revolution which would involve the fall of Nicholas II in view of the difficulties of attacking the Tsar directly, the Germans had concentrated their efforts against the Tsarina and begun a subterranean campaign of defamation against her. It was skillfully planned and began to show results before long. They had stopped at nothing in the way of calumny. They had adopted the classic procedure, so well known to history, of striking the monarch in the person of his consort. it is, of course, always easier to damage the reputation of a woman, especially when she is a foreigner. Realising all the advantages to be derived from the fact that the Tsarina was a German princess, they had endeavoured to suggest very cunningly that she was- a traitor to Russia. It was the best method of compromising her in the eyes of the nation. The accusation had been favorably received in certain quarters in Russia and had become a formidable weapon against the dynasty.

He gives one anecdote supporting this:

I was able to ascertain this for myself at the end of 1915. At the house of some friends one day I met a young officer whose political opinions were favorable to the Court. He told us with intense indignation that on the Tsarina's orders someone had taken gifts and money to the German officers being treated at the same hospital as he had been in. This envoy had not even entered the rooms occupied by the Russian officers. Astonished at his story, I asked for details. An enquiry was ordered. It completely confirmed the story I had been told, but it was impossible to trace the individual who had succeeded, by the use of forged papers, in making the authorities believe he had an official mission. Pure chance had brought me into contact with one of the many provocations organised by German spies with German money.

I haven't read too much about this period, and the idea of Germany trying to attack the Tsar from within Russia like this isn't something I've come across before. I know it's wise to take the words of someone so close to the Imperial Family with caution, so I'd like to know if there is much evidence for his claims that some of the many damaging rumours about the Tsar and Tsarina were instigated by Germans, rather than Russian opponents.