Adversaries may encode data with a standard data encoding system to make the content of command and control traffic more difficult to detect. Command and control (C2) information can be encoded using a standard data encoding system that adheres to existing protocol specifications. Common data encoding schemes include ASCII, Unicode, hexadecimal, Base64, and MIME.(Citation: Wikipedia Binary-to-text Encoding)(Citation: Wikipedia Character Encoding) Some data encoding systems may also result in data compression, such as gzip.
ESXi shell (BusyBox) or VMware utilities (openssl, python if present) used to Base64/hex encode data from datastore or config files → followed by abnormal egress from the host (NSX/flow logs) with asymmetric bytes_out or HTTPS posts to non-management endpoints.
Processes use base64/xxd/openssl/python Objective‑C APIs to encode data (seen in EndpointSecurity exec events or Unified Logs) → quick outbound connections with large bytes_out or HTTP POSTs carrying Base64/MIME bodies.
Process invokes a standard encoder (e.g., PowerShell -enc, certutil -encode, base64 via .NET/Invoke-Expression) or emits long Base64/hex literals → shortly followed by outbound network egress with high bytes_out:bytes_in ratio or HTTP headers/payloads containing Base64/MIME blocks.