When allowed outbound connectivity, the binary performed:

| Destination | Protocol | Port | Payload | |-------------|----------|------|---------| | 185.62.73.45 | TCP | 443 | TLS‑encrypted JSON containing system fingerprint | | 51.38.90.12 | UDP | 53 | DNS query for xkzq4d.com (C2 domain) | | 10.0.0.5 (internal) | SMB | 445 | Attempted file share access (likely for lateral movement) |

All TLS handshakes used TLS 1.3 with a self‑signed certificate (SHA‑256 fingerprint 3B1D…).

Use binwalk to identify embedded files:

binwalk Complex_4627.bin

Look for strings: strings Complex_4627.bin | head -20. If you see references to .exe, CreateProcess, or DNS beacons, do not run.

Our investigation adhered to a four‑phase workflow designed for repeatability and safety:

All analysis was performed on an isolated network with no outbound connectivity, except when deliberately enabling a simulated C2 server for controlled behavior.

| Offset (hex) | Size (bytes) | Description | |--------------|--------------|-------------| | 0x0000 | 0x2000 | Random padding (high entropy) | | 0x2000 | 0x1000 | PE‑Stub – tiny Windows PE loader (32‑bit) | | 0x3000 | 0x4000 | Encrypted Payload A (AES‑256‑CBC) | | 0x7000 | 0x2000 | Compressed Payload B (UPX‑like) | | 0x9000 | 0x1800 | Embedded Resources (PNG, ZIP) | | 0xA800 | 0x5800 | Self‑Modifying Code Region | | 0x10000 | 0x1000 | Signature Block (RSA‑2048) |

The entropy of the first 0x2000 bytes is 7.98 bits/byte, typical of random padding used to thwart signature‑based detection.