2025-12-23 (TUESDAY): MACSYNC STEALER INFECTION

ASSOCIATED FILES:

• 2025-12-23-IOCs-for-MacSync-Stealer.txt.zip   1.0 kB   (1,030 bytes)
• 2025-12-23-MacSync-Stealer-traffic.pcap.zip   83.4 kB   (83,447 bytes)
• 2025-12-23-MacSync-Stealer-malware.zip   31.5 MB   (31,547,913 bytes)

REFERENCE:

• From ClickFix to code signed: the quiet shift of MacSync Stealer malware by Jamf Threat Labs

NOTES:

• This post provides a pcap of the infection traffic seen after running the MacSync Stealer malware on a macOS system.
• I modified the pcap to corrupt the exfitrated zip archive from the C2 traffic so it doesn't give away my host info.
• The zkcall[.]net site also has downloads links for Windows malware (DonutLoader) and Linux (link didn't work).

2025-12-23 (TUESDAY): MACSYNC STEALER INFECTION

REFERENCE:

- https://www.jamf.com/blog/macsync-stealer-evolution-code-signed-swift-malware-analysis/

ASSOCIATED MALWARE:

- SHA256 hash: b591bfbab57cc69ce985fbc426002ef00826605257de0547f20ebcfecc3724c2
- File size: 31,476,506 bytes
- File name: zk-call-messenger-installer-3.9.2-lts.dmg
- Retrieved from: hxxps[:]//zkcall[.]net/api/download?fileId=350&versionId=5&os=MACOS_APPLE&section=/download
- File type: Macintosh Disk Image, lzfse encoded, lzvn compressed
- File description: Downloaded DMG image for MacSync Stealer

- SHA256 hash: 173ff5ede7c28163ceaa9440de8a02cef26295f8be06b6b0f90b0a4284471bc2
- File size: 308,576 bytes
- File name: devupdatesuite-helper
- File type: Mach-O universal binary with 2 architectures: [x86_64:Mach-O 64-bit executable x86_64]
             [arm64:Mach-O 64-bit executable arm64]
- File description: Mach-O executable for MacSync Stealer from the installer.app content extracted from the DMG file

TRAFFIC GENERATED BY THE MACH-O BINARY:

- Date/Time of the infection: 2025-12-23 03:52 UTC

- obsidiangate[.]space - HTTPS traffic (TLSv1.3)
- focusgroovy[.]com - GET /dynamic?txd=985683bd660c0c47c6be513a2d1f0a554d52d241714bb17fb18ab0d0f8cc2dc6
- focusgroovy[.]com - POST /gate

IMAGES

Shown above:  Downloading the initial file, a DMG image.

Shown above:  From the DMG image to the malicious Mach-O file.

Shown above:  Traffic generated by the MacSync Stealer malware.

Shown above:  Example of data exfiltrated through network traffic generated by the MacSync Stealer sample.

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