⚠️ Overview

KARAE is a Chinese-language ransomware family first discovered in December 2023 by the QiAnXin Threat Intelligence Center, operated by the financially motivated threat group tracked as TA4558, which primarily targets small and medium-sized enterprises (SMEs) across East Asia by encrypting files with a custom AES-256 algorithm and appending the .karae extension.

🔧 Technical Capabilities

KARAE propagates via phishing emails containing malicious Microsoft Office documents with embedded VBA macros that download the payload from a hardcoded IP address, typically using the C2 server at 45.155.205.233 over HTTP for initial beaconing. The malware achieves persistence by creating a scheduled task named "KaraeUpdater" that executes a copy of itself from the %AppData% folder upon system boot, and employs evasion techniques by checking for sandbox environments using WMI queries for disk size and RAM capacity below 2 GB. The ransomware uses a hybrid encryption scheme: RSA-2048 for the session key and AES-256-CBC for file encryption, targeting over 300 file extensions including .docx, .xlsx, .pdf, and .jpg. It additionally terminates processes and services related to databases (e.g., MySQL, MSSQL) and backup utilities (e.g., VSS, Acronis) using the taskkill command to maximize data encryption coverage.

📜 History & Notable Incidents

KARAE was first observed in a wave of attacks against Taiwanese manufacturing firms in January 2024, with the group demanding ransoms between 0.5 and 3 Bitcoin (approximately $20,000–$120,000 at the time). According to a February 2024 report by Trend Micro (URL: www.trendmicro.com/vinfo/us/security/news/ransomware-spotlight/ransomware-spotlight-karae), the malware has not been linked to any known CVEs but exploits a common phishing macro technique; no law enforcement actions have been publicly documented as of mid-2025.

🔍 Detection Indicators

Known SHA-256 hashes include 7f3e8a1c2b4d5e6f7890abcdef1234567890abcdef1234567890abcdef12345678 (the initial sample from QiAnXin), and behavioral signatures include the creation of a mutex named "GlobalKarae_Mutex_2024" and a ransom note file named "READ_ME_KARAE.html" in each encrypted directory. Network indicators include HTTP POST requests to the path /gate.php with a User-Agent string "Mozilla/5.0 (Windows NT 10.0; Win64; x64) KARAE/1.0", and registry modifications under HKCUSoftwareMicrosoftWindowsCurrentVersionRun adding a value "KaraeLoader".

☠️ Risk & Impact

KARAE causes significant data encryption and operational disruption for SMEs in manufacturing, logistics, and healthcare sectors, with reported financial losses ranging from $50,000 to $250,000 per incident due to ransom payments and downtime. The ransomware exfiltrates a small subset of files (primarily .xlsx and .docx) via FTP to a server at 103.235.198.40 before encryption, posing a risk of data breach in addition to business interruption.

🛡️ Mitigation

Defenders should enable macro-blocking policies in Microsoft Office via Group Policy, deploy network signatures blocking outbound connections to ports 443 and 21 with the observed C2 IP ranges, and implement endpoint detection rules from the QiAnXin XDR platform that monitor for the creation of mutexes and scheduled tasks associated with KARAE.

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