The Lazarus group is currently one of the most active and prolific APT actors. In 2018, Kaspersky published a report on one of their campaigns, named Operation AppleJeus. Notably, this operation marked the first time Lazarus had targeted macOS users, with the group inventing a fake company in order to deliver their manipulated application and exploit the high level of trust among potential victims. As a result of our ongoing efforts, we identified significant changes to the group’s attack methodology. To attack macOS users, the Lazarus group has developed homemade macOS malware, and added an authentication mechanism to deliver the next stage payload very carefully, as well as loading the next-stage payload without touching the disk. In addition, to attack Windows users, they have elaborated a multi-stage infection procedure, and significantly changed the final payload. We assess that the Lazarus group has been more careful in its attacks following the release of Operation AppleJeus and they have employed a number of methods to avoid being detected.
Life after Operation AppleJeus
After releasing Operation AppleJeus, the Lazarus group continued to use a similar modus operandi in order to compromise cryptocurrency businesses. We found more macOS malware similar to that used in the original Operation AppleJeus case. This macOS malware used public source code in order to build crafted macOS installers. The malware authors used QtBitcoinTrader developed by Centrabit.
Change of Windows malware
During our ongoing tracking of this campaign, we found that one victim was compromised by Windows AppleJeus malware in March 2019. Unfortunately, we couldn’t identify the initial installer, but we established that the infection started from a malicious file named WFCUpdater.exe. At that time, the actor used a fake website: wfcwallet[.]com
The actor used a multi-stage infection like before, but the method was different. The infection started from .NET malware, disguised as a WFC wallet updater (a9e960948fdac81579d3b752e49aceda). Upon execution, this .NET executable checks whether the command line argument is “/Embedding” or not. This malware is responsible for decrypting the WFC.cfg file in the same folder with a hardcoded 20-byte XOR key (82 d7 ae 9b 36 7d fc ee 41 65 8f fa 74 cd 2c 62 b7 59 f5 62). This mimics the wallet updater connected to the C2 addresses:
wfcwallet.com (resolved ip: 126.96.36.199)
www.chainfun365.com (resolved ip: 188.8.131.52)
We found several fake websites that were still online when we were investigating their infrastructure. They created fake cryptocurrency-themed websites, but they were far from perfect and most of the links didn’t work.
We were able to identify several victims in this Operation AppleJeus sequel. Victims were recorded in the UK, Poland, Russia and China. Moreover, we were able to confirm that several of the victims are linked to cryptocurrency business entities.
The actor altered their macOS and Windows malware considerably, adding an authentication mechanism in the macOS downloader and changing the macOS development framework. The binary infection procedure in the Windows system differed from the previous case. They also changed the final Windows payload significantly from the well-known Fallchill malware used in the previous attack. We believe the Lazarus group’s continuous attacks for financial gain are unlikely to stop anytime soon.
Since the initial appearance of Operation AppleJeus, we can see that over time the authors have changed their modus operandi considerably. We assume this kind of attack on cryptocurrency businesses will continue and become more sophisticated.
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