# T1560.003_archive-via-custom-method

> An adversary may compress or encrypt data that is collected prior to exfiltration using a custom method.

- Skill: `cyberstrikeus/t1560-003-archive-via-custom-method` (Agent Skill)
- Install (CLI): `npx skillmds@latest add cyberstrikeus/t1560-003-archive-via-custom-method`
- Raw SKILL.md: https://api.skillmd.com/api/skills/cyberstrikeus/t1560-003-archive-via-custom-method/raw
- Safety review: PASS (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: cyberstrikeus (https://skillmd.com/u/cyberstrikeus)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/cyberstrikeus/t1560-003-archive-via-custom-method

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# T1560.003 Archive via Custom Method

> **Sub-technique of:** T1560

## High-Level Description

An adversary may compress or encrypt data that is collected prior to exfiltration using a custom method. Adversaries may choose to use custom archival methods, such as encryption with XOR or stream ciphers implemented with no external library or utility references. Custom implementations of well-known compression algorithms have also been used.

## Kill Chain Phase

- Collection (TA0009)

**Platforms:** Linux, macOS, Windows

## What to Check

- [ ] Identify if Archive via Custom Method technique is applicable to target environment
- [ ] Check Linux systems for indicators of Archive via Custom Method
- [ ] Check macOS systems for indicators of Archive via Custom Method
- [ ] Check Windows systems for indicators of Archive via Custom Method
- [ ] Assess detection coverage (1 detection strategies)

## How to Test

### Manual Testing

1. **Identify Attack Surface**: Determine if the target environment is susceptible to Archive via Custom Method by examining the target platforms (Linux, macOS, Windows).

2. **Assess Existing Defenses**: Review whether mitigations for T1560.003 are in place. If defenses are absent or misconfigured, this technique may be exploitable.

3. **Execute Test**: Use tools and methods described in the MITRE ATT&CK page and external references below.

> **Note**: No Atomic Red Team tests available for this technique. See [Atomic Red Team GitHub](https://github.com/redcanaryco/atomic-red-team) for updates.

## Remediation Guide

No specific mitigations documented for this technique.

## Detection

### Detect Archiving via Custom Method (T1560.003)

## Risk Assessment

| Finding                                        | Severity | Impact     |
| ---------------------------------------------- | -------- | ---------- |
| Archive via Custom Method technique applicable | Low      | Collection |

## CWE Categories

| CWE ID  | Title                             |
| ------- | --------------------------------- |
| CWE-200 | Exposure of Sensitive Information |

## References

- [ESET Sednit Part 2](http://www.welivesecurity.com/wp-content/uploads/2016/10/eset-sednit-part-2.pdf)
- [Atomic Red Team - T1560.003](https://github.com/redcanaryco/atomic-red-team/tree/master/atomics/T1560.003)
- [MITRE ATT&CK - T1560.003](https://attack.mitre.org/techniques/T1560/003)