Russian Hackers Use Zulip Chat App for Covert C&C in Diplomatic Phishing Attacks

An ongoing campaign targeting ministries of foreign affairs of NATO-aligned countries points to the involvement of Russian threat actors.
The phishing attacks feature PDF documents with diplomatic lures, some of which are disguised as coming from Germany, to deliver a variant of a malware called Duke, which has been attributed to APT29 (aka BlueBravo, Cloaked Ursa, Cozy Bear, Iron Hemlock,