Sophos Managed Detection and Response initiated a threat hunt across all customers after the detection of abuse of a vulnerable legitimate VMware executable (vmnat.exe) to perform dynamic link library (DLL) side-loading on one customer’s network. In a search for similar incidents in telemetry, MDR ultimately uncovered a complex, persistent cyberespionage campaign targeting a high-profile government organization in Southeast Asia. As described in the first part of this report, we identified at least three distinct clusters of intrusion activity present in the organization’s network from at least March 2023 through December 2023.

The three security threat activity clusters—which we designated as Alpha (STAC1248), Bravo (STAC1870), and Charlie (STAC1305) – are assessed with high confidence to operate on behalf of Chinese state interests. In this continuation of our report, we will provide deeper technical analysis of the three activity clusters, including the tactics, techniques, and procedures (TTPs) used in the campaign, aligned to activity clusters where possible. We also provide additional technical details on prior compromises within the same organization that appear to be connected to the campaign.