# Attack Ent T1027 013 Encrypted Encoded File

> Analyze MITRE ATT&CK T1027.013 Encrypted/Encoded File in the enterprise matrix. Use for TTP triage, detection engineering, hunting, defensive emulation planning, mitigations, incident response mapping, ATT&CK coverage, or questions mentioning T1027.013, Encrypted/Encoded File, or enterprise ATT&CK. Adversaries may encrypt or encode files to obfuscate strings, bytes, and other specific patterns to impede detection.

- Skill: `santosomar/attack-ent-t1027-013-encrypted-encoded-file` (Agent Skill, multi-file: 11 files)
- Install (CLI): `npx skillmds@latest add santosomar/attack-ent-t1027-013-encrypted-encoded-file`
- Raw SKILL.md: https://api.skillmd.com/api/skills/santosomar/attack-ent-t1027-013-encrypted-encoded-file/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- License: MITRE ATT&CK Terms of Use apply to ATT&CK-derived content. See h
- Author: santosomar (https://skillmd.com/u/santosomar)
- Updated: 2026-09-22
- Page: https://skillmd.com/skills/santosomar/attack-ent-t1027-013-encrypted-encoded-file

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# MITRE ATT&CK T1027.013: Encrypted/Encoded File

## When to use this skill

Use this skill when the task involves T1027.013, Encrypted/Encoded File, enterprise ATT&CK, TTP mapping, detection engineering, hunting, incident-response enrichment, control validation, or authorized adversary-emulation planning. Treat it as a defensive analysis aid: keep outputs focused on understanding, detecting, mitigating, and safely validating this ATT&CK sub-technique.

## Technique context

- ATT&CK domain: enterprise
- ATT&CK ID: T1027.013
- Technique name: Encrypted/Encoded File
- Type: sub-technique
- ATT&CK URL: https://attack.mitre.org/techniques/T1027/013
- Tactics: stealth
- Platforms: Linux, macOS, Windows
- Required permissions: Not specified
- Effective permissions: Not specified
- Defenses bypassed: Not specified

## ATT&CK description

Adversaries may encrypt or encode files to obfuscate strings, bytes, and other specific patterns to impede detection. Encrypting and/or encoding file content aims to conceal malicious artifacts within a file used in an intrusion. Many other techniques, such as [Software Packing](https://attack.mitre.org/techniques/T1027/002), [Steganography](https://attack.mitre.org/techniques/T1027/003), and [Embedded Payloads](https://attack.mitre.org/techniques/T1027/009), share this same broad objective. Encrypting and/or encoding files could lead to a lapse in detection of static signatures, only for this malicious content to be revealed (i.e., [Deobfuscate/Decode Files or Information](https://attack.mitre.org/techniques/T1140)) at the time of execution/use.

This type of file obfuscation can be applied to many file artifacts present on victim hosts, such as malware log/configuration and payload files.(Citation: File obfuscation) Files can be encrypted with a hardcoded or user-supplied key, as well as otherwise obfuscated using standard encoding schemes such as Base64.

The entire content of a file may be obfuscated, or just specific functions or values (such as C2 addresses). Encryption and encoding may also be applied in redundant layers for additional protection.

For example, adversaries may abuse password-protected Word documents or self-extracting (SFX) archives as a method of encrypting/encoding a file such as a [Phishing](https://attack.mitre.org/techniques/T1566) payload. These files typically function by attaching the intended archived content to a decompressor stub that is executed when the file is invoked (e.g., [User Execution](https://attack.mitre.org/techniques/T1204)).(Citation: SFX - Encrypted/Encoded File) 

Adversaries may also abuse file-specific as well as custom encoding schemes. For example, Byte Order Mark (BOM) headers in text files may be abused to manipulate and obfuscate file content until [Command and Scripting Interpreter](https://attack.mitre.org/techniques/T1059) execution.

## Agent workflow

1. Clarify scope: identify the system, asset class, log sources, cloud or endpoint platform, and whether the user wants triage, detection, coverage assessment, or safe emulation planning.
2. Load bundled resources as needed: use `references/technique-profile.json` for structured metadata, `references/detection-and-mitigation.md` for triage and telemetry guidance, `references/known-threat-context.md` for ATT&CK relationship context, and `templates/` for repeatable outputs.
3. Map observations to ATT&CK: compare the user's evidence to the ATT&CK description, tactics, platforms, and known procedure patterns before asserting a match.
4. Produce defensive outputs: prioritize hypotheses, telemetry requirements, detection logic ideas, validation steps, containment guidance, and mitigations.
5. Preserve uncertainty: distinguish confirmed evidence, plausible indicators, assumptions, and gaps. Recommend what to collect next.
6. Stay safe: do not provide malware, credential theft, persistence, evasion, destructive automation, or unauthorized exploitation instructions. For adversary emulation, keep steps bounded to approved lab or control-validation contexts and omit operational abuse details.

## Bundled resources

- `references/technique-profile.json`: machine-readable ATT&CK metadata for this technique.
- `references/detection-and-mitigation.md`: detection notes, telemetry checklist, triage questions, mitigation candidates, and false-positive considerations.
- `references/known-threat-context.md`: ATT&CK relationship context with attribution cautions.
- `templates/detection-brief.md`: detection engineering brief template.
- `templates/hunt-plan.md`: threat hunt plan template.
- `templates/incident-response-note.md`: incident response note template.
- `templates/coverage-assessment.md`: ATT&CK coverage assessment template.
- `scripts/render_brief.py`: local helper that renders a Markdown defensive brief from `technique-profile.json`.
- `assets/output-schema.json`: JSON schema for structured technique analysis outputs.

To generate a quick brief, run `python scripts/render_brief.py --output brief.md` from inside this skill directory, or adapt the templates directly.

## Detection guidance

No ATT&CK detection guidance was present in the source STIX object.

## Useful telemetry and data sources

- Not specified in the STIX object.

## Mitigations to consider

- Antivirus/Antimalware
- Behavior Prevention on Endpoint

## Known threat context

Use these examples only as contextual leads, not as proof that an observed event is this technique:

- 2025 Poland Wiper Attacks (campaign)
- 3CX Supply Chain Attack (campaign)
- ANELLDR (malware)
- APT-C-36 (intrusion-set)
- APT18 (intrusion-set)
- APT19 (intrusion-set)
- APT28 (intrusion-set)
- APT32 (intrusion-set)
- APT33 (intrusion-set)
- APT39 (intrusion-set)
- APT41 DUST (campaign)
- Aria-body (malware)
- AshTag (malware)
- Astaroth (malware)
- Attor (malware)
- AuditCred (malware)
- Avenger (malware)
- BITTER (intrusion-set)
- BLINDINGCAN (malware)
- BLUELIGHT (malware)

## Recommended output pattern

When responding with this skill, structure the answer as:

- Assessment: whether the evidence supports this ATT&CK mapping and why.
- Evidence: specific indicators, logs, behaviors, and assumptions.
- Detection: telemetry sources, analytic logic, and tuning considerations.
- Response: containment, eradication, recovery, and validation actions.
- Coverage gaps: missing logs, sensors, controls, or environmental details.
- References: include the ATT&CK URL and any user-provided evidence references.

## ATT&CK contributors

- Andrew Northern, @ex_raritas
- David Galazin @themalwareman1
- Jai Minton, @Cyberraiju