F5, a Seattle-based maker of networking software, disclosed the breach on Wednesday. F5 said a “sophisticated” threat group working for an undisclosed nation-state government had surreptitiously and persistently dwelled in its network over a “long-term.” Security researchers who have responded to similar intrusions in the past took the language to mean the hackers were inside the F5 network for years.

During that time, F5 said, the hackers took control of the network segment the company uses to create and distribute updates for BIG IP, a line of server appliances that F5 ...

Toward the end of the second incident that Volexity worked involving Dark Halo, the actor was observed accessing the e-mail account of a user via OWA. This was unexpected for a few reasons, not least of which was the targeted mailbox was protected by MFA. Logs from the Exchange server showed that the attacker provided username and password authentication like normal but were not challenged for a second factor through Duo. The logs from the Duo authentication server further showed that no attempts had been made to log into the account in question. Volexity was able to confirm that session hijacking was not involved and, through a memory dump of the OWA server, could also confirm that the attacker had presented cookie tied to a Duo MFA session named ...

During our investigation to date, we have found that the attacker targeted and accessed certain Red Team assessment tools that we use to test our customers’ security. These tools mimic the behavior of many cyber threat actors and enable FireEye to provide essential diagnostic security services to our customers. None of the tools contain zero-day exploits. Consistent with our goal to protect the community, we are proactively releasing methods and means to detect the use of our stolen Red Team tools...