T1679 Selective Exclusion

---
name: "T1679_selective-exclusion"
description: "Adversaries may intentionally exclude certain files, folders, directories, file types, or system components from encryption or tampering during a ransomware or malicious payload execution."
category: "configuration"
version: "18.1"
author: "cyberstrike-official"
tags:
  - mitre-attack
  - enterprise
  - t1679
  - defense-evasion
  - windows
technique_id: "T1679"
tactic: "defense-evasion"
all_tactics:
  - defense-evasion
platforms:
  - Windows
mitre_url: "https://attack.mitre.org/techniques/T1679"
tech_stack:
  - windows
cwe_ids:
  - CWE-693
chains_with: []
prerequisites: []
severity_boost: {}
---

# T1679 Selective Exclusion

## High-Level Description

Adversaries may intentionally exclude certain files, folders, directories, file types, or system components from encryption or tampering during a ransomware or malicious payload execution. Some file extensions that adversaries may avoid encrypting include `.dll`, `.exe`, and `.lnk`.

Adversaries may perform this behavior to avoid alerting users, to evade detection by security tools and analysts, or, in the case of ransomware, to ensure that the system remains operational enough to deliver the ransom notice.

Exclusions may target files and components whose corruption would cause instability, break core services, or immediately expose the attack. By carefully avoiding these areas, adversaries maintain system responsiveness while minimizing indicators that could trigger alarms or otherwise inhibit achieving their goals.

## Kill Chain Phase

- Defense Evasion (TA0005)

**Platforms:** Windows

## What to Check

- [ ] Identify if Selective Exclusion technique is applicable to target environment
- [ ] Check Windows systems for indicators of Selective Exclusion
- [ ] Assess detection coverage (1 detection strategies)

## How to Test

### Manual Testing

1. **Identify Attack Surface**: Determine if the target environment is susceptible to Selective Exclusion by examining the target platforms (Windows).

2. **Assess Existing Defenses**: Review whether mitigations for T1679 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

### Detection of Selective Exclusion

## Risk Assessment

| Finding                                  | Severity | Impact          |
| ---------------------------------------- | -------- | --------------- |
| Selective Exclusion technique applicable | Low      | Defense Evasion |

## CWE Categories

| CWE ID  | Title                        |
| ------- | ---------------------------- |
| CWE-693 | Protection Mechanism Failure |

## References

- [Palo Alto Unit 42 Medusa Group Medusa Ransomware January 2024](https://unit42.paloaltonetworks.com/medusa-ransomware-escalation-new-leak-site/)
- [Atomic Red Team - T1679](https://github.com/redcanaryco/atomic-red-team/tree/master/atomics/T1679)
- [MITRE ATT&CK - T1679](https://attack.mitre.org/techniques/T1679)