feat(SAFE-T1901): add Outbound Webhook C2 technique

Signed-off-by: hackathons-saurabh <saurabh.ssy@gmail.com>

Author: saurabh-yergattikar

README.md

@@ -123,7 +123,7 @@ The SAFE-MCP framework defines 14 tactics that align with the MITRE ATT&CK metho
 | ATK-TA0009 | Collection | SAFE-T1803 | Database Dump | Use SQL tool to SELECT * from prod DB |
 | ATK-TA0009 | Collection | SAFE-T1804 | API Data Harvest | Loop over customer REST endpoints via HTTP tool |
 | ATK-TA0009 | Collection | SAFE-T1805 | Context Snapshot Capture | Query vector store embeddings wholesale |
-| **ATK-TA0011** | **Command and Control** | SAFE-T1901 | Outbound Webhook C2 | LLM calls "http.post" to attacker URL with commands/results |
+| **ATK-TA0011** | **Command and Control** | [SAFE-T1901](/techniques/SAFE-T1901/README.md) | Outbound Webhook C2 | Abuse of outbound HTTP webhooks for command and control |
 | ATK-TA0011 | Command and Control | SAFE-T1902 | Covert Channel in Responses | Encode data in whitespace or markdown links returned to chat |
 | ATK-TA0011 | Command and Control | SAFE-T1903 | Malicious Server Control Channel | Attacker operates rogue server; every tool call doubles as heartbeat |
 | ATK-TA0011 | Command and Control | SAFE-T1904 | Chat-Based Backchannel | LLM embeds base64 blobs in normal answers that another bot decodes |

techniques/SAFE-T1901/README.md

@@ -0,0 +1,98 @@
+# SAFE-T1901 : Outbound Webhook C2
+
+## Tactic  
+**Command and Control (ATK-TA0011)**  
+
+---
+
+## Description
+Outbound Webhook C2 is a technique where an adversary abuses legitimate outbound HTTP webhook mechanisms to establish covert command-and-control (C2) channels from a Model Context Protocol (MCP) environment.  
+Because MCP agents and tools routinely use HTTPS for integration with external services (Slack, GitHub, Jira, etc.), malicious webhook calls blend with normal traffic, making detection difficult.  
+
+This mirrors MITRE ATT&CK technique [T1567.004 – Exfiltration Over Webhook](https://attack.mitre.org/techniques/T1567/004/) and expands it to AI agent ecosystems.
+
+---
+
+## How It Works
+1. **Initial Access** – Attacker gains code execution inside an MCP agent or server (e.g., through malicious tool registration or supply-chain package).  
+2. **Webhook Setup** – They embed an attacker-controlled URL (`https://discord.com/api/webhooks/...`, `https://hooks.slack.com/services/...`, or custom endpoint) in configuration or environment variables.  
+3. **Beaconing & Tasking** – The compromised component periodically issues small HTTPS POST requests to the webhook, sending status or encoded data and receiving instructions from the attacker’s channel.  
+4. **Command Execution / Exfiltration** – Responses from the webhook or attacker messages drive additional actions or data uploads.  
+5. **Persistence / Evasion** – Traffic appears as benign API usage; the attacker may rotate URLs or use trusted domains to avoid detection.  
+
+---
+
+## Examples
+- **Malicious packages** in npm and PyPI (2025 reports) that exfiltrated developer tokens to Discord webhooks under benign names like “post-install analytics.”  
+- **KurayStealer** and similar malware families use Slack and Discord webhooks as lightweight C2 channels to send logs and receive tasks.  
+- In an enterprise MCP setup, a backdoored tool could POST conversation summaries to a remote webhook every hour, evading firewall rules because HTTPS egress is permitted.
+
+---
+
+## Impact
+| Property | Level | Explanation |
+|-----------|-------|-------------|
+| Confidentiality | **High** | Sensitive data or tokens can leave the organization undetected via legitimate HTTPS channels |
+| Integrity | **Medium** | External commands may alter agent behavior or workflow outputs |
+| Availability | **Low** | Usually stealthy and low-bandwidth; minor resource impact |
+
+---
+
+## Detection
+**Network Indicators**
+- Frequent small HTTPS POSTs to rare domains (e.g., `discord.com`, `webhook.site`, dynamic tunnels like `*.ngrok.io`) from MCP hosts not expected to communicate externally.  
+- Unusual SNI or TLS fingerprints in outbound connections.  
+
+**Host Indicators**
+- Config files or .env entries containing webhook-like URLs.  
+- Tools or scripts embedding HTTP client calls without documented purpose.  
+
+**Example SIEM rule (pseudo-Sigma)**  
+```yaml
+title: Outbound Webhook C2 Detection
+logsource: network/proxy
+detection:
+  selection:
+    url|contains:
+      - "discord.com/api/webhooks"
+      - "hooks.slack.com/services"
+      - "webhook.site"
+      - "ngrok.io"
+    method: POST
+  condition: selection
+level: medium
+```
+
+---
+
+## Mitigation
+**Preventive**
+1. Restrict egress from MCP agents to approved domains (HTTP allow-listing).  
+2. Proxy all outbound HTTP(S) traffic through a controlled gateway with inspection and rate limits.  
+3. Disallow hard-coded webhook URLs in code; require secret stores with rotation and audit trails.  
+4. Require manifest review for tools requesting network capabilities.  
+5. Implement signed or authenticated webhook payloads and mutual TLS for approved integrations.  
+
+**Detective**
+1. Monitor and baseline outbound destinations per server.  
+2. Scan source repos and pipelines for webhook URL patterns.  
+3. Correlate proxy logs with MCP task timestamps to spot covert beaconing.  
+
+**Response**
+- Block or revoke the malicious webhook URL, rotate tokens, and collect forensic logs.  
+
+---
+
+## References
+- MITRE ATT&CK – [T1567.004 Exfiltration Over Webhook](https://attack.mitre.org/techniques/T1567/004/)  
+- CISA Advisory on Webhook Exfiltration (2024)  
+- Invicti Research – *Securing Webhooks Against Abuse* (2023)  
+- HackerOne – *Webhook Security Best Practices* (2023)  
+- Reports on Malicious npm/PyPI Packages Exfiltrating to Discord (Oct 2025)  
+- KurayStealer Analysis – Use of Discord Webhooks as C2 (2023)
+
+---
+
+## MITRE ATT&CK Mapping
+**ATT&CK Technique:** T1567.004 – Exfiltration Over Webhook  
+**ATT&CK Tactic:** Command and Control (TA0011)**