Symantec has reported that the China-linked espionage group known as Billbug—also referred to as Lotus Blossom, Lotus Panda, Bronze Elgin, and Thrip—conducted a sustained intrusion campaign against multiple organizations in a Southeast Asian country between August 2024 and February 2025. The campaign involved the use of several custom tools, including loaders, credential stealers, and a reverse SSH utility.
According to Symantec, this activity appears to continue a series of operations previously observed in late 2023, which targeted various government and critical infrastructure organisations across Southeast Asia. While Chinese attribution has been suggested, specific attribution to an individual actor remains inconclusive. Identified targets include a government ministry, an air traffic control organisation, a telecommunications provider, and a construction company.
Additional intrusions were reported against a news agency and an air freight company in neighbouring countries. The campaign leveraged DLL sideloading techniques, utilising legitimate executables from Trend Micro and Bitdefender to load malicious code.
Symantec’s analysis detailed how these binaries were used to sideload malicious DLLs, which decrypted and executed payloads designed to maintain persistence and enable further compromise of targeted systems. Billbug has been active since at least 2009, with a documented history of targeting government, defence, telecommunications, and critical infrastructure sectors in Southeast Asia and beyond.
Symantec and other cybersecurity researchers have tracked the group across multiple campaigns, including previous operations involving backdoors like Hannotog and Sagerunex. The recent report also references related findings from Cisco Talos, which provided indicators of compromise connected to the same campaign.
Symantec noted that Billbug continues to adapt its techniques, including the use of compromised legitimate software and custom malware, to conduct espionage operations across the region.
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