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Slack (Zencoder) — agentic threat model

9.3AIVSS 9.3 · Critical

This Slack MCP server acts as a high-risk bridge between untrusted external channel content and real-world messaging side effects, presenting significant risk of prompt injection leading to unauthorized message posting or data exfiltration.

OWASP AIVSS score rationale

AIVSS = (CVSS_Base + AARS) × Mitigation_Factor, where AARS = (10 − CVSS_Base) × (Factor_Sum / 10) × ThM
CVSS base 8.5AARS uplift 0.79Factor sum 4.8/10Threat ×1.1Mitigation ×1.0
Autonomy of Action
0.70
Goal-Driven Planning
0.40
Self-Modification
0.10
Dynamic Tool Use
0.80
Persistent Memory
0.20
Contextual Awareness
0.60
Dynamic Identity
0.50
Multi-Agent Interactions
0.30
Non-Determinism
0.70
Opacity & Reflexivity
0.50

Scored with the canonical OWASP AIVSS formula (AIVSS calculator reference); agentic risk factors estimated from the agent’s described capabilities.

MAESTRO 7-layer threat model

Per-layer threats for this agent. Layers tagged “not certain from listing” are general, caveated commentary where the public description didn’t pin that layer.

L1 · Foundation Models⚠ not certain from listing

Not certain from the listing — the underlying LLM is not specified as this is an MCP server, but any connected model is highly vulnerable to indirect prompt injection via untrusted Slack message history read by the tool.

L2 · Data Operations✓ mapped

The agent reads Slack channel history, which acts as an untrusted, dynamic external data source. There are no built-in sanitization or provenance checks mentioned for this ingested message data.

L3 · Agent Frameworks✓ mapped

Exposes powerful tools for reading/posting messages and managing channels. Insecure tool integration or lack of strict input validation allows an LLM to be manipulated into executing unauthorized Slack actions.

L4 · Deployment & Infrastructure✓ mapped

Supports stdio and HTTP transports. Security relies entirely on the host environment's isolation and how securely the Slack bot/user token is stored and accessed at runtime.

L5 · Evaluation & Observability⚠ not certain from listing

Not certain from the listing — there is no mention of built-in logging, guardrails, or anomaly detection to monitor for malicious tool calls or suspicious message-posting patterns.

L6 · Security & Compliance (cross-cutting)✓ mapped

Authentication relies on a Slack bot/user token. Authorization is binary (determined by the token's scopes) with no granular, user-level access controls or human-in-the-loop confirmation mechanisms described.

L7 · Agent Ecosystem✓ mapped

As an MCP server, it is designed to be integrated into broader agent ecosystems, creating a high risk of cascading failures if another compromised agent invokes these Slack tools to exfiltrate data or spam channels.

MAESTRO — the 7-layer agentic threat-modeling framework (Cloud Security Alliance / Ken Huang).