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Resurfaced ChillyHell macOS Backdoor Discovered

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📰 2 unique sources, 2 articles

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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.

Timeline

  1. 10.09.2025 14:59 📰 2 articles · ⏱ 6d ago

    New ChillyHell macOS Backdoor Sample Discovered

    The new version of the ChillyHell backdoor malware for macOS was discovered in a sample uploaded to VirusTotal on May 2, 2025. The malware, first seen in 2022, was used in attacks against Ukrainian officials and has resurfaced with updated capabilities. It employs multiple persistence mechanisms and unique evasion tactics, including timestamping. Apple has revoked the notarization of the associated developer certificates. 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. The malware establishes C2 communication with hard-coded servers 93.88.75[.]252 or 148.72.172[.]53 over HTTP or DNS. It uses timestomping to modify timestamps of created artifacts to evade detection. ChillyHell can launch a reverse shell to the C2 IP address and includes a module named ModuleSUBF to enumerate user accounts and conduct brute-force attacks.

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