APT41 is a malicious cyber threat group that appears to be based in China. They have been identified and involved with cyber threat activity associated with financial gain. APT41 is unique because they have developed very advanced and sophisticated malware tools but use them for financial gain. This level of sophistication is more typical of threat actors involved with espionage and the theft of military and intelligence secrets. APT41 appears to have been active on all fronts since approximately 2014.
APT41 has unsurprisingly been targeting organizations and information which will be valuable to China’s 5-Year Economic Development Plan. In support of APT41’s long-term goal to exfiltrate sensitive information they can use for financial gain, they maintain silent access to many organizations in critical industries such as telecommunications and high technology. APT41 has also conducted operations against new/media firms, higher education, and sometimes individuals. In one case, APT41 targeted a hotel reservation system before a visit from Chinese officials! We’d guess that this was to determine the quality of security arrangements and identify other hotel guests as potential threats.
APT41 has been known to steal source code and digital certificates, which are then used to sign malware fraudulently. Additionally, once APT41 can access a software production environment, they can use this access to embed malware in what appear to be legitimate software distribution files otherwise. Supply chain attacks such as these have become well known, as of late, in that the potential distribution of trusted malware-embedded software can sometimes be done to thousands of unsuspecting victims.
APT41 does target very precisely and works to make the intent of the campaign challenging to discern. This targeting is done through multi-stage ops, which restrict delivery to only APT41’s victims.
APT41 uses an extensive collection of 40+ malware tools and families of tools to support their techniques. Spear phishing is often used with simple attachments such as .chm files to trick and compromise their victims. Once they have gained entry, APT41 can then leverage additional techniques and additional malware. One single campaign by APT41 can leverage dozens of different malware tools, including rootkits, keyloggers, backdoors, and much more. In search of long-term persistence, APT41 has been identified using rootkits and master boot record bootkits to obfuscate malware. Bootkits are particularly stealthy because the code is executed before the operating system’s initialization.
In summary, APT41 is a highly skilled and motivated adversary. APT41’s work in using supply chain compromise to target select individuals, consistent signing of malware using compromised digital certificates, and deployment of bootkits. These techniques appear almost unique to APT41, making them all the more dangerous.
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