# T1102.003_one-way-communication

> Adversaries may use an existing, legitimate external Web service as a means for sending commands to a compromised system without receiving return output over the Web service channel.

- Skill: `cyberstrikeus/t1102-003-one-way-communication` (Agent Skill)
- Install (CLI): `npx skillmds@latest add cyberstrikeus/t1102-003-one-way-communication`
- Raw SKILL.md: https://api.skillmd.com/api/skills/cyberstrikeus/t1102-003-one-way-communication/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/t1102-003-one-way-communication

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# T1102.003 One-Way Communication

> **Sub-technique of:** T1102

## High-Level Description

Adversaries may use an existing, legitimate external Web service as a means for sending commands to a compromised system without receiving return output over the Web service channel. Compromised systems may leverage popular websites and social media to host command and control (C2) instructions. Those infected systems may opt to send the output from those commands back over a different C2 channel, including to another distinct Web service. Alternatively, compromised systems may return no output at all in cases where adversaries want to send instructions to systems and do not want a response.

Popular websites and social media acting as a mechanism for C2 may give a significant amount of cover due to the likelihood that hosts within a network are already communicating with them prior to a compromise. Using common services, such as those offered by Google or Twitter, makes it easier for adversaries to hide in expected noise. Web service providers commonly use SSL/TLS encryption, giving adversaries an added level of protection.

## Kill Chain Phase

- Command and Control (TA0011)

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

## What to Check

- [ ] Identify if One-Way Communication technique is applicable to target environment
- [ ] Check Linux systems for indicators of One-Way Communication
- [ ] Check macOS systems for indicators of One-Way Communication
- [ ] Check Windows systems for indicators of One-Way Communication
- [ ] Verify mitigations are bypassed or absent (2 known mitigations)
- [ ] Assess detection coverage (1 detection strategies)

## How to Test

### Manual Testing

1. **Identify Attack Surface**: Determine if the target environment is susceptible to One-Way Communication by examining the target platforms (Linux, macOS, Windows).

2. **Assess Existing Defenses**: Review whether mitigations for T1102.003 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

### M1021 Restrict Web-Based Content

Web proxies can be used to enforce external network communication policy that prevents use of unauthorized external services.

### M1031 Network Intrusion Prevention

Network intrusion detection and prevention systems that use network signatures to identify traffic for specific adversary malware can be used to mitigate activity at the network level.

## Detection

### Detect One-Way Web Service Command Channels

## Risk Assessment

| Finding                                    | Severity | Impact              |
| ------------------------------------------ | -------- | ------------------- |
| One-Way Communication technique applicable | Low      | Command And Control |

## CWE Categories

| CWE ID  | Title                              |
| ------- | ---------------------------------- |
| CWE-300 | Channel Accessible by Non-Endpoint |

## References

- [University of Birmingham C2](https://arxiv.org/ftp/arxiv/papers/1408/1408.1136.pdf)
- [Atomic Red Team - T1102.003](https://github.com/redcanaryco/atomic-red-team/tree/master/atomics/T1102.003)
- [MITRE ATT&CK - T1102.003](https://attack.mitre.org/techniques/T1102/003)