A China-linked threat actor has been attributed to a cyber attack targeting an U.S. non-profit organization with an aim to establish long-term persistence, as part of broader activity aimed at U.S. entities that are linked to or involved in policy issues. The organization, according to a report from Broadcom's Symantec and Carbon Black teams, is "active in attempting to influence U.S. government policy on international issues." The attackers managed to gain access to the network for several weeks in April 2025.
"APT28 is abusing Outlook as a covert channel through a VBA macro backdoor named NotDoor," Jason Soroko, Senior Fellow at Sectigo, explains. "Delivery uses DLL sideloading of a malicious SSPICLI.dll by the signed OneDrive.exe to disable macro protections and stage commands. The macro watches inbound mail for a trigger word and can exfiltrate data upload files and run commands. This blends with trusted binaries and normal mail flow and can slip past perimeter tools and basic detections."