: Short for "Free" (or Retail/Final) . In Windows development terminology, a "FRE" build is a standard retail version optimized for performance, as opposed to a "CHK" (Checked) build used by developers for debugging.
| Feature | Details | |---------|---------| | | Microsoft Visual C++ 2019, /O2 optimization, /MT static runtime | | Exported functions | WinMain , LoadPayload , SetPersistence , SendBeacon | | Import table | kernel32.dll , advapi32.dll , ws2_32.dll , urlmon.dll , crypt32.dll | | Anti‑analysis tricks | • Checks for debugger presence ( IsDebuggerPresent ) • Uses NtQueryInformationProcess to detect sandbox VM (checks for VMware, VirtualBox, Hyper‑V) • Employs XOR‑based string obfuscation and runtime decryption | | Payload delivery | Encrypted (AES‑256‑CBC) payload embedded in a resource section ( RT_RCDATA ). The key is derived at runtime from a combination of the host’s hardware GUID and a hard‑coded secret. | | Execution flow | 1. Self‑validation (integrity checksum). 2. Persistence set‑up (registry / scheduled task). 3. C2 contact (HTTPS GET to a domain generated from the host’s MAC address). 4. Payload decryption & injection (CreateRemoteThread into a legitimate system process, e.g., svchost.exe ). | ces_x64frev
The loader itself focuses on and retrieving additional payloads . The actual “impact” (ransomware, data theft, etc.) is determined by the second stage delivered after the C2 handshake. : Short for "Free" (or Retail/Final)
If the label isn't enough and you need the exact build number (like 22H2 or 21H1), you can use the Command Prompt without even installing the OS. Plug in your USB. Open as Administrator. The key is derived at runtime from a
| Protocol | Destination | Observed Patterns | |----------|-------------|-------------------| | (TLS 1.2) | *.cloudfront.net , *.akamaihd.net , and custom domains ( a1b2c3d4[.]com ) | Encrypted beacon containing system info, installed software list, and a short‑lived crypto‑nonce. | | DNS (TXT queries) | payload.[random].domain.tld | Used when the primary C2 is unreachable; the TXT record holds a Base64‑encoded secondary payload. | | SMB (internal) | \\192.168.*.*\share | Rarely used for lateral movement; copies the loader to other hosts on the same subnet. |