A China-linked cyberespionage group was recently observed targeting a state legislature in the United States, Symantec warns.
Active since at least 2010, the group is tracked as APT27, Bronze Union, Budworm, Emissary Panda, Iron Tiger, Lucky Mouse, and TG-3390 (Threat Group 3390), and has been observed targeting various entities worldwide, mainly focusing on the Middle East and Asia.
In a new report detailing APT27’s recent activities, Symantec notes that the attack on the US state legislature is the first time in several years that it has seen the cyberespionage group targeting a US entity.
Over the past six months, Symantec also observed the threat actor targeting a Middle Eastern government, a hospital in South East Asia, and a multinational electronics manufacturer.
As part of these attacks, APT27 was seen exploiting Log4j vulnerabilities (CVE-2021-44228 and CVE-2021-45105) in the Apache Tomcat service to deploy web shells, and using virtual private servers (VPS) as command and control (C&C) servers.
The group continues to rely on the HyperBro malware as the main backdoor, which is often executed using DLL side-loading – in some cases, a custom HyperBro loader has been used.
In recent attacks, the cyberspies abused the endpoint privilege management application CyberArk Viewfinity for side-loading the malicious payload.
“This involves the attackers placing a malicious DLL in a directory where a legitimate DLL is expected to be found. The attacker then runs the legitimate application (having installed it themselves). The legitimate application then loads and executes the payload,” Symantec explains.
Other malware and tools that APT27 has been using include the PlugX/Korplug trojan, Cobalt Strike beacon (penetration testing tool with shell code loading capabilities), LaZagne (credential dumping), IOX (proxy and port-forwarding), Fast Reverse Proxy (FRP), and Fscan (intranet scanning).
The HyperBro malware, which is a backdoor exclusive to APT27, was recently mentioned by the NSA, FBI and CISA in an alert describing the TTPs used by APTs in attacks targeting a US defense industrial base organization.
“While there were frequent reports of Budworm targeting U.S. organizations six to eight years ago, in more recent years the group’s activity appears to have been largely focused on Asia, the Middle East, and Europe. […] A resumption of attacks against U.S.-based targets could signal a change in focus for the group,” Symantec concludes.