North Korean APT37 Subgroup ChinopuNK Conducts Ransomware Campaign in South Korea

A new FileFix social engineering campaign impersonates Meta account suspension warnings to trick users into installing the StealC infostealer malware. The attack uses steganography to hide malicious scripts and executables within a JPG image. The campaign targets various credentials, cryptocurrency wallets, and cloud services. The FileFix technique abuses the File Explorer address bar to execute PowerShell commands, bypassing traditional detection methods. The attack was discovered by Acronis and observed over a two-week period, with multiple variants using different payloads and domains. The StealC malware aims to steal sensitive information from infected devices, including browser credentials, messaging app data, and cryptocurrency wallets. The FileFix technique was created by red team researcher mr.d0x and has been previously used by the Interlock ransomware gang. The attack uses a multilingual phishing site to trick users into copying and pasting a malicious command into the File Explorer address bar. The campaign abuses Bitbucket repositories to host malicious components, leveraging trust in the platform to bypass detection. The FileFix campaign is the most widespread, customized, and sophisticated to date, targeting users in over 16 countries. The phishing site has been translated into at least 16 different languages. The attack chain involves a phishing email impersonating Facebook security, warning users of account suspension. The attack uses AI-generated images in the steganography process. The FileFix technique is more elegant and less suspicious than ClickFix, using File Explorer instead of the Run dialog. The FileFix attack offers a broader range of high-value targets due to its use of File Explorer. Security researcher Eliad Kimhy predicts an increase in FileFix attacks in the near future.

A supply chain attack targeting the npm registry has compromised over 187 packages maintained by multiple developers. The attack uses a malicious script (bundle.js) to steal credentials from developer machines. The compromised packages include various npm modules used in different projects. The attack is capable of targeting both Windows and Linux systems. The malicious script scans for secrets using TruffleHog's credential scanner and transmits them to an external server controlled by the attackers. Developers are advised to audit their environments and rotate credentials if the affected packages are present.

A new ransomware variant, HybridPetya, has been discovered. It resembles the Petya/NotPetya malware but includes the ability to bypass UEFI Secure Boot using the CVE-2024-7344 vulnerability. HybridPetya encrypts the Master File Table (MFT) on NTFS-formatted partitions and can compromise modern UEFI-based systems. The ransomware operates through a bootkit and an installer, with the bootkit managing encryption and decryption processes. The ransomware has been observed in samples uploaded to VirusTotal in February 2025, with no evidence of active use in the wild. The vulnerability exploited by HybridPetya was patched in January 2025. The ransomware encrypts the MFT and displays a fake CHKDSK message to deceive victims. It demands a $1,000 ransom in Bitcoin, with a total of $183.32 received between February and May 2025. The ransom note provides an option for victims to enter a decryption key after payment, which triggers the decryption process. The bootkit also recovers legitimate bootloaders from backups created during installation. The ransomware triggers a system crash during bootloader changes, ensuring the bootkit binary is executed upon reboot. HybridPetya may be a research project, proof-of-concept, or early version of a cybercrime tool under limited testing. HybridPetya combines the destructive capabilities of NotPetya, the recoverable encryption functionality of Petya ransomware, and the ability to bypass Secure Boot protections. It can deploy malicious UEFI payloads directly to the EFI System Partition and encrypt the Master File Table (MFT). HybridPetya's ability to install harmful code directly into a computer's UEFI firmware makes it hard for security teams to detect. The emergence of HybridPetya highlights the growing threat from UEFI bootkits that reside at a computer's startup sequence level.

A new version of the ChillyHell modular backdoor malware targeting macOS has been discovered. The malware, first seen in 2022, was used in attacks against Ukrainian officials and has now resurfaced with updated capabilities. ChillyHell provides remote access, payload delivery, and password brute-forcing. The malware was notarized by Apple in 2021 and has been publicly hosted on Dropbox since then. The malware disguises itself as an executable applet and deploys as a persistent backdoor, capable of retrieving sensitive data and evading detection. It employs multiple persistence mechanisms and can communicate over different protocols. It also features timestamping to cover its tracks. Apple has revoked the notarization of the developer certificates associated with the malware after being notified. ChillyHell is written in C++ and targets Intel architectures. It is attributed to an uncategorized threat cluster dubbed UNC4487, which has been active since at least October 2022. UNC4487 is suspected to be an espionage actor targeting Ukrainian government entities.

A new malware campaign involving MostereRAT, a banking malware-turned-remote access Trojan (RAT), has been identified. This campaign uses sophisticated evasion techniques, including the use of an obscure programming language, disabling of security tools, and mutual TLS (mTLS) for command-and-control communications to maintain long-term access to compromised systems. The malware targets Microsoft Windows users in Japan, deploying through phishing emails and weaponized Word documents. MostereRAT's capabilities include persistence, privilege escalation, AV evasion, and remote access tool deployment. The campaign highlights the importance of removing local administrator privileges and blocking unapproved remote access tools. The malware's design reflects long-term, strategic, and flexible objectives, with capabilities to extend functionality, deploy additional payloads, and apply evasion techniques. These features point to an intent to maintain persistent control over compromised systems, maximize the utility of victim resources, and retain ongoing access to valuable data.