New Turtle Ransomware Spotted Targeting macOS

Researchers uncovered a cross-platform Go ransomware dubbed 'Turtle' that encrypts macOS files with AES using a hardcoded key, making decryption trivial.

Objective-See analyzed a new ransomware sample, internally dubbed "Turtle" (also referred to as "TURTLERANS" or "TurmiRansom" in its own strings), after a researcher flagged a suspicious VirusTotal upload. The malware was found bundled in a zip archive alongside compiled variants for Windows, Linux, and macOS (both Intel and Apple Silicon), suggesting a Windows-first development pattern later ported to macOS. The macOS binary is only ad-hoc signed and not notarized, meaning Gatekeeper would block execution absent explicit user approval or an exploit chain.

Written in Go, the malware walks the working directory and encrypts files matching .doc, .docx, and .txt extensions using AES in CTR mode, renaming encrypted files with a ".TURTLERANSv0" suffix. Analysis revealed embedded Chinese-language strings ("加密文件" — "encrypt files") and a hardcoded, non-random AES key ("wugui123wugui123" — "wugui" meaning turtle in Chinese) with a static zero IV, allowing the researcher to trivially write a Python decryptor and fully recover encrypted content.

While the sample poses minimal real-world risk to macOS users today — given the poor cryptographic implementation, lack of notarization, and narrow file-extension targeting — it reinforces a broader trend of ransomware authors extending targeting to macOS. The author also demonstrated that legacy heuristic-based tools like Objective-See's open-source "RansomWhere?" (monitoring rapid file I/O and encryption behavior) were able to generically detect and block the malware without prior signature knowledge.

Source reporting: https://objective-see.org/blog/blog_0x76.html