Governmental organizations in Southeast Asia are the target of a new campaign that aims to collect sensitive information by means of a previously undocumented Windows backdoor dubbed HazyBeacon.
The activity is being tracked by Palo Alto Networks Unit 42 under the moniker CL-STA-1020, where “CL” stands for “cluster” and “STA” refers to “state-backed motivation.”
“The threat actors behind this cluster of activity have been collecting sensitive information from government agencies, including information about recent tariffs and trade disputes,” security researcher Lior Rochberger said in a Monday analysis.
Southeast Asia has increasingly become a focal point for cyber espionage due to its role in sensitive trade negotiations, military modernization, and strategic alignment in the U.S.–China power dynamic. Targeting government agencies in this region can provide valuable intelligence on foreign policy direction, infrastructure planning, and internal regulatory shifts that influence regional and global markets.
The exact initial access vector used to deliver the malware is currently not known, although evidence shows the use of DLL side-loading techniques to deploy it on compromised hosts. Specifically, it involves planting a malicious version of a DLL called “mscorsvc.dll” along with the legitimate Windows executable, “mscorsvw.exe.”
Once the binary is launched, the DLL proceeds to establish communication with an attacker-controlled URL that allows it to execute arbitrary commands and download additional payloads. Persistence is achieved by means of a service that ensures the DLL is launched even after a reboot of the system.
HazyBeacon is notable for the fact that it leverages Amazon Web Services (AWS) Lambda URLs for command-and-control (C2) purposes, demonstrating threat actors’ continued abuse of legitimate services to fly under the radar and escape detection.
“AWS Lambda URLs are a feature of AWS Lambda that allows users to invoke serverless functions directly over HTTPS,” Rochberger explained. “This technique uses legitimate cloud functionality to hide in plain sight, creating a reliable, scalable and difficult-to-detect communication channel.”
Defenders should pay attention to outbound traffic to rarely used cloud endpoints like *.lambda-url.*.amazonaws.com, especially when initiated by unusual binaries or system services. While AWS usage itself isn’t suspicious, context-aware baselining—such as correlating process origins, parent-child execution chains, and endpoint behavior—can help distinguish legitimate activity from malware leveraging cloud-native evasion.
Downloaded among the payloads is a file collector module that’s responsible for harvesting files matching a specific set of extensions (e.g., doc, docx, xls, xlsx, and pdf) and within a time range. This includes attempts to search for files related to the recent tariff measures imposed by the United States.
The threat actor has also been found to employ other services like Google Drive and Dropbox as exfiltration channels so as to blend in with normal network traffic and transmit the gathered data. In the incident analyzed by Unit 42, attempts to upload the files to the cloud storage services are said to have been blocked.
In the final stage, the attackers run cleanup commands to avoid leaving traces of their activity, deleting all the archives of staged files and other payloads downloaded during the attack.
“The threat actors used HazyBeacon as the main tool for maintaining a foothold and collecting sensitive information from the affected governmental entities,” Rochberger said. “This campaign highlights how attackers continue to find new ways to abuse legitimate, trusted cloud services.”
HazyBeacon reflects a broader trend of advanced persistent threats using trusted platforms as covert channels—a tactic often referred to as “living off trusted services” (LOTS). As part of this cloud-based malware cluster, similar techniques have been observed in threats using Google Workspace, Microsoft Teams, or Dropbox APIs to evade detection and facilitate persistent access.
