North Korean Hackers Use Fake News to Spread ‘Hidden Risk’ Malware

North Korean hackers are targeting cryptocurrency businesses with a sophisticated new malware campaign, dubbed “Hidden Risk.” Learn how this stealthy attack works, the techniques used, and how to protect yourself from this growing threat.

North Korean state-sponsored APT group ‘BlueNoroff‘ is targeting crypto-related businesses in a campaign dubbed ‘Hidden Risk’, according to SentinelOne’s findings shared with Hackread.com. 

SentinelLabs’ threat researchers reportedly discovered that BlueNoroff, a subgroup of the larger North Korean state-backed Lazarus Group, is targeting cryptocurrency and DeFi businesses using use email and PDF-based lures with fake news headlines/crypto-related stories in a campaign that began in July 2024.

Examples of fake news, posts and announcements used in the attack (Via SentinelOne)

Analyzing the Attack

Researchers noted that attackers have employed unique tactics to evade detection and compromise victim systems. The attack begins with a well-crafted phishing email that lures unsuspecting victims into clicking on a malicious link that leads to a seemingly legitimate PDF document, which is actually hiding a malicious Swift-language-based Mac application cleverly disguised as a PDF reader (signed/notarized on 19 October 2024).

“The application is disguised as a link to a PDF document relating to a cryptocurrency topic such as “Hidden Risk Behind New Surge of Bitcoin Price”, “Altcoin Season 2.0-The Hidden Gems to Watch” and “New Era for Stablecoins and DeFi, CeFi”,” researchers explained.

Once executed, this application discreetly downloads a decoy PDF (Hidden Risk) and then downloads/executes a malicious x86-64 binary (“growth”) on both Intel and Apple silicon machines. 

Growth installs itself persistently and acts as a backdoor. It gathers sensitive information about the infected system, communicates with a remote server controlled by the attackers, and can potentially receive and execute commands.

Persistence Mechanism

To ensure persistence, the attackers have opted for a unique method of modifying the Zsh configuration file (zshenv) by adding malicious code to ensure its continued presence. This is a critical file used by the Zsh shell and is sourced during every Zsh session, allowing the backdoor to automatically execute upon system startup, even after a reboot.

The BlueNoroff Connection

SentinelLabs’ researchers have linked this campaign with BlueNoroff because it resembles techniques from their past campaigns, including parsing server commands and saving them in hidden files. The campaign’s network infrastructure analysis also reveals connections to domains used in previous campaigns using services like NameCheap and Quickpacket for hosting.

Furthermore, the malware uses a User-Agent string previously linked to BlueNoroff’s “RustBucket” malware and exploits a developer account to get their malware notarized by Apple, bypassing security measures like Gatekeeper.

Staying Protected

BlueNoroff has a history of targeting cryptocurrency exchanges, venture capital firms, and banks and poses a constant threat to the industry. They prefer using PDF-based lures mainly because PDF documents are widely used and trusted, making them ideal for malicious payloads.

Hackread recently reported BlueNoroff-linked malware, TodoSwift, disguised as a legitimate PDF viewer and ObjCShellz malware targeting macOS to run remote shell commands on Intel and Arm Macs.

Therefore, it is important to double-check email addresses, watch out for emails from anonymous sources, and avoid clicking on links in unknown emails, especially if they ask for downloading applications/PDFs. MacOS users must remain aware of risks given the sudden rise in macOS-oriented attacks.

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