T1027.009No distinct observable

Embedded Payloads

StealthLinux, macOS, Windows

Where this stands

A reviewer read the telemetry and concluded there is nothing here to detect that a sibling technique does not already cover.

All three analytics in DET0214 ask for a property of a file's own bytes — 'hidden embedded resources or secondary payloads', 'anomalies in file size vs. functionality', 'appended sections', 'nested, encoded, or run-only embedded payloads' — that none of the nine log sources across the three platforms exposes as a field, and what each analytic adds beyond that is a correlation lib/sigma cannot express. Windows AN0599 offers Sysmon EventID 11 (file_event: TargetFilename, CreationUtcTime, the writing process) and EventID 1 (process_creation); neither carries a file-size field, so MITRE's OverlaySizeThreshold knob has nothing to bind to, and 'dropped child binaries' is ProcessTreeDepth plus TimeWindow, a tree-and-time join this brief's rule model does not support. […]

Covered instead by T1140, T1027.013.

What the technique is

Adversaries may embed payloads within other files to conceal malicious content from defenses. Otherwise seemingly benign files (such as scripts and executables) may be abused to carry and obfuscate malicious payloads and content. In some cases, embedded payloads may also enable adversaries to Subvert Trust Controls by not impacting execution controls such as digital signatures and notarization tickets. Adversaries may embed payloads in various file formats to hide payloads. This is similar to Steganography, though does not involve weaving malicious content into specific bytes and patterns related to legitimate digital media formats. For example, adversaries have been observed embedding payloads within or as an overlay of an otherwise benign binary. Adversaries have also been observed nesting payloads (such as executables and run-only scripts) inside a file of the same format. Embedded content may also be used as Process Injection payloads used to infect benign system processes. These embedded then injected payloads may be used as part of the modules of malware designed to provide specific features such as encrypting C2 communications in support of an orchestrator module. For example, an embedded module may be injected into default browsers, allowing adversaries to then communicate via the network.

Read it on attack.mitre.org

What MITRE says you would watch

AN0599
Detection of executables or scripts containing hidden embedded resources or secondary payloads, often with anomalies in file size vs. functionality or dropped child binaries.
AN0600
Detection of shell scripts, ELF binaries, or archives containing embedded secondary payloads, self-extracting components, or unusual compression behavior during runtime.
AN0601
Detection of Mach-O binaries or AppleScripts that contain nested, encoded, or run-only embedded payloads dropped at runtime.