Lazarus APT uses fake cryptocurrency apps to spread AppleJeus Malware

The North Korea-linked Lazarus APT spreads fake cryptocurrency apps under the fake brand BloxHolder to install the AppleJeus malware.

Volexity researchers warn of a new malware campaign conducted by the North Korea-linked Lazarus APT against cryptocurrency users. The threat actors were observed spreading fake cryptocurrency apps under the fake brand BloxHolder to deliver the AppleJeus malware for initial access to networks and steal crypto assets.

The APT group employed the AppleJeus malware since at least 2018 to steal cryptocurrencies from the victims.

The new campaign observed by Volexity started in June 2022, the APT group registered the domain name bloxholder[.]com, and then set up a website related to automated cryptocurrency trading.

The new campaign attributed to Lazarus started in June 2022 and was active until at least October 2022.

In this campaign, the threat actors used the “bloxholder[.]com” domain, a clone of the HaasOnline automated cryptocurrency trading platform.

The website is a clone of the legitimate website, HaasOnline (haasonline[.]com.)

The attackers used the website to distribute a Windows MSI installer masquerading as the BloxHolder app, which was used to install AppleJeus malware along with the QTBitcoinTrader app.

“This discovered file, the  “BloxHolder application”, is actually another case of AppleJeus being installed alongside the open-source cryptocurrency trading application QTBitcoinTrader that is available on GitHub. This same legitimate application has previously been used by the Lazarus Group, as documented in this report from CISA.” reads the report published by Volexity. “The MSI file is used to install both the malicious and legitimate applications at the same time.”

In October 2022, the researchers observed the Lazarus Group installing AppleJeus using a weaponized Microsoft Office document, named ‘OKX Binance & Huobi VIP fee comparision.xls,’ instead of an MSI installer.

The document contains a macro split into two parts, the first one is used to decode a base64 blob that contains a second OLE object containing a second macro. The initial document also stores several variables, encoded using base64, that allow defining where the malware will be deployed in the infected system.

The last stage payload is downloaded from a public file-sharing service, OpenDrive. 

Volexity experts were not able to retrieve the final payload employed since October, but they noticed similarities in the DLL sideloading mechanism which is similar to the one used in the attacks relying on MSI installer.

“While the file was no longer available at the time of analysis, based on public sandbox results for the file in question, the downloaded payload, “Background.png”, embeds the following three files:

• “Logagent.exe” – a legitimate file (md5: eb1e19613a6a260ddd0ae9224178355b)
• “wsock32.dll” – a side-loaded library internally named HijackingLib.dll (md5: e66bc1e91f1a214d098cf44ddb1ae91a)
• “56762eb9-411c-4842-9530-9922c46ba2da” – an encoded payload decoded by “wsock32.dll”

“continues the analysis. “The three files are dropped on disk using hardcoded offsets that can be found in the second macro.”

Experts speculate Lazarus used DLL sideloading to avoid malware analysis, the threat actors also noticed that recent AppleJeus samples obfuscated strings and API calls using a custom algorithm.

“The Lazarus Group continues its effort to target cryptocurrency users, despite ongoing attention to their campaigns and tactics. Perhaps in an attempt to allude detection, they have decided to use chained DLL side-loading to load their payload. Additionally, Volexity has not previously noted the use of Microsoft Office documents to deploy AppleJeus variants.” concludes volexity. “Despite these changes, their targets remain the same, with the cryptocurrency industry being a focus as a means for the DPRK to bolster their finances.”

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Pierluigi Paganini

(SecurityAffairs – hacking, APT)

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