Signal — the complete, unedited output of the deterministic mcptrustchecker engine v1.13.0, scanned . Every finding, capability tag and score component below is exactly what the engine produced — no AI, no post-processing.
{
"tool": {
"name": "mcptrustchecker",
"version": "1.13.0",
"methodologyVersion": "mcptrustchecker-1.13"
},
"target": {
"id": "signal-mcp",
"source": {
"kind": "package",
"origin": "signal-mcp"
},
"server": {
"name": "signal-mcp"
}
},
"grade": "B",
"score": {
"score": 83,
"threatScore": 91,
"grade": "B",
"band": "B",
"categorySubtotals": {
"injection": 9.45,
"exfiltration": 0,
"permissions": 0,
"supply-chain": 0,
"network": 0,
"hygiene": 0
},
"vector": [
{
"kind": "threat",
"ruleId": "MTC-INJ-SCHEMA-1",
"category": "injection",
"severity": "medium",
"confidence": "strong",
"rawWeight": 9,
"confidenceMult": 0.7,
"diminishingFactor": 1,
"appliedPenalty": 6.3
},
{
"kind": "threat",
"ruleId": "MTC-INJ-SCHEMA-1",
"category": "injection",
"severity": "medium",
"confidence": "strong",
"rawWeight": 9,
"confidenceMult": 0.7,
"diminishingFactor": 0.5,
"appliedPenalty": 3.15
},
{
"kind": "client",
"term": "capability-exposure",
"level": "high",
"label": "capability blast radius (high) — client exposure if the model is manipulated",
"appliedPenalty": 6
},
{
"kind": "client",
"term": "verification-discount",
"level": "none",
"label": "publisher verification (unlinked) — no provenance/repo link, but the shipped source was fully read",
"appliedPenalty": 2
},
{
"kind": "client",
"term": "coverage-honesty",
"level": "source",
"label": "inspection depth (source) — how much of the target the scan could see",
"appliedPenalty": 0
}
],
"gatesFired": [],
"methodologyVersion": "mcptrustchecker-1.13"
},
"capability": {
"level": "high",
"reasons": [
"can send data / act on an external service",
"can execute shell commands or code"
],
"tags": [
"external-sink",
"code-exec"
]
},
"coverage": {
"level": "source",
"inputs": {
"toolSurface": true,
"implementationSource": true,
"packageMetadata": true,
"liveTransport": false
},
"caveats": [
"Tools were statically extracted from the published source (79 recovered), not enumerated from a running server. Tool-poisoning, Unicode-smuggling, capability and toxic-flow analysis ran on this inferred surface, but a mis-parsed registration could be missed or mis-attributed, so tool-derived findings are capped below “confirmed”. To grade the real runtime surface, scan the running server: --command \"npx -y <package>\"."
]
},
"findings": [
{
"ruleId": "MTC-SRC-002",
"title": "Shell/command execution in server code (src/signal_mcp/cli.py)",
"category": "permissions",
"severity": "high",
"confidence": "strong",
"description": "In the server's implementation (`src/signal_mcp/cli.py:483`): Spawning a shell/process is command-execution capability; with unsanitized tool input it is command injection / RCE. This is read from the code itself — not from the tool description — so a poisoned server cannot hide it behind honest-looking metadata.",
"remediation": "Review this call path: confirm it never receives unsanitized tool input, constrain it, or remove it. Treat a server whose code reaches these sinks as high-capability regardless of what its tools claim.",
"location": {
"kind": "server",
"name": "src/signal_mcp/cli.py"
},
"evidence": "ragma: no cover subprocess.run([ \"signal-cli\", \"-u\", account, \"daemon\", f\"--http\", f\"loc",
"owasp": "LLM05:2025 Improper Output Handling",
"data": {
"rule": "MTC-SRC-002",
"file": "src/signal_mcp/cli.py",
"line": 483,
"nonRuntime": false
}
},
{
"ruleId": "MTC-SRC-002",
"title": "Shell/command execution in server code (src/signal_mcp/client.py)",
"category": "permissions",
"severity": "high",
"confidence": "strong",
"description": "In the server's implementation (`src/signal_mcp/client.py:185`): Spawning a shell/process is command-execution capability; with unsanitized tool input it is command injection / RCE. This is read from the code itself — not from the tool description — so a poisoned server cannot hide it behind honest-looking metadata.",
"remediation": "Review this call path: confirm it never receives unsanitized tool input, constrain it, or remove it. Treat a server whose code reaches these sinks as high-capability regardless of what its tools claim.",
"location": {
"kind": "server",
"name": "src/signal_mcp/client.py"
},
"evidence": ".5) proc = subprocess.Popen( [ \"signal-cli\", \"-u\", self.account,",
"owasp": "LLM05:2025 Improper Output Handling",
"data": {
"rule": "MTC-SRC-002",
"file": "src/signal_mcp/client.py",
"line": 185,
"nonRuntime": false
}
},
{
"ruleId": "MTC-SRC-002",
"title": "Shell/command execution in server code (src/signal_mcp/config.py)",
"category": "permissions",
"severity": "high",
"confidence": "strong",
"description": "In the server's implementation (`src/signal_mcp/config.py:46`): Spawning a shell/process is command-execution capability; with unsanitized tool input it is command injection / RCE. This is read from the code itself — not from the tool description — so a poisoned server cannot hide it behind honest-looking metadata.",
"remediation": "Review this call path: confirm it never receives unsanitized tool input, constrain it, or remove it. Treat a server whose code reaches these sinks as high-capability regardless of what its tools claim.",
"location": {
"kind": "server",
"name": "src/signal_mcp/config.py"
},
"evidence": "JVM start) result = subprocess.run( [\"signal-cli\", \"listAccounts\"], capture_output=True, tex",
"owasp": "LLM05:2025 Improper Output Handling",
"data": {
"rule": "MTC-SRC-002",
"file": "src/signal_mcp/config.py",
"line": 46,
"nonRuntime": false
}
},
{
"ruleId": "MTC-SRC-002",
"title": "Shell/command execution in server code (src/signal_mcp/desktop.py)",
"category": "permissions",
"severity": "high",
"confidence": "strong",
"description": "In the server's implementation (`src/signal_mcp/desktop.py:67`): Spawning a shell/process is command-execution capability; with unsanitized tool input it is command injection / RCE. This is read from the code itself — not from the tool description — so a poisoned server cannot hide it behind honest-looking metadata.",
"remediation": "Review this call path: confirm it never receives unsanitized tool input, constrain it, or remove it. Treat a server whose code reaches these sinks as high-capability regardless of what its tools claim.",
"location": {
"kind": "server",
"name": "src/signal_mcp/desktop.py"
},
"evidence": "): result = subprocess.run( [\"security\", \"find-generic-password\", \"-s\", service, \"-w\"],",
"owasp": "LLM05:2025 Improper Output Handling",
"data": {
"rule": "MTC-SRC-002",
"file": "src/signal_mcp/desktop.py",
"line": 67,
"nonRuntime": false
}
},
{
"ruleId": "MTC-INJ-SCHEMA-1",
"title": "Description names a credential store the tool cannot reach",
"category": "injection",
"severity": "medium",
"confidence": "strong",
"description": "Tool \"get_unread\" describes a credential store (SSH keys, cloud credentials, a keychain or an equivalent) that nothing in its input schema can address. A tool's interface is the honest statement of what it touches; prose that reaches past it is addressed to the model, not to a reader.",
"remediation": "Remove the reference, or expose the target as an explicit, validated parameter so the client can see and consent to what the tool reads.",
"location": {
"kind": "tool",
"name": "get_unread",
"field": "description"
},
"evidence": "Keychain",
"owasp": "LLM02:2025 Sensitive Information Disclosure",
"data": {}
},
{
"ruleId": "MTC-INJ-SCHEMA-1",
"title": "Description names a credential store the tool cannot reach",
"category": "injection",
"severity": "medium",
"confidence": "strong",
"description": "Tool \"import_desktop\" describes a credential store (SSH keys, cloud credentials, a keychain or an equivalent) that nothing in its input schema can address. A tool's interface is the honest statement of what it touches; prose that reaches past it is addressed to the model, not to a reader.",
"remediation": "Remove the reference, or expose the target as an explicit, validated parameter so the client can see and consent to what the tool reads.",
"location": {
"kind": "tool",
"name": "import_desktop",
"field": "description"
},
"evidence": "Keychain",
"owasp": "LLM02:2025 Sensitive Information Disclosure",
"data": {}
},
{
"ruleId": "MTC-CAP-007",
"title": "Unconstrained URL/host parameter \"url\" on \"set_webhook\"",
"category": "network",
"severity": "medium",
"confidence": "heuristic",
"description": "Tool \"set_webhook\" takes a URL/host parameter \"url\" with no allowlist/pattern. An outbound-request tool with an unbounded destination enables SSRF and cloud-metadata access (e.g. 169.254.169.254).",
"remediation": "Allowlist destinations or constrain the parameter; block private/link-local addresses server-side.",
"location": {
"kind": "tool",
"name": "set_webhook",
"field": "inputSchema.properties.url"
},
"owasp": "LLM06:2025 Excessive Agency",
"data": {
"param": "url"
}
},
{
"ruleId": "MTC-SUP-011",
"title": "Package declares no source repository",
"category": "supply-chain",
"severity": "info",
"confidence": "strong",
"description": "\"signal-mcp\" declares no repository URL, so its published artifact cannot be compared against reviewable source.",
"remediation": "Prefer packages that link to public, reviewable source.",
"location": {
"kind": "package",
"name": "signal-mcp"
}
}
],
"toxicFlows": [],
"capabilities": [
{
"tool": "send_message",
"tags": [
"external-sink"
],
"reasons": {
"external-sink": [
"keyword \"send_message\"",
"parameter \"recipient\""
]
}
},
{
"tool": "send_group_message",
"tags": [],
"reasons": {}
},
{
"tool": "send_note_to_self",
"tags": [],
"reasons": {}
},
{
"tool": "edit_message",
"tags": [
"external-sink"
],
"reasons": {
"external-sink": [
"parameter \"recipient\""
]
}
},
{
"tool": "receive_messages",
"tags": [],
"reasons": {}
},
{
"tool": "receive_direct",
"tags": [],
"reasons": {}
},
{
"tool": "list_contacts",
"tags": [],
"reasons": {}
},
{
"tool": "list_groups",
"tags": [],
"reasons": {}
},
{
"tool": "get_conversation",
"tags": [],
"reasons": {}
},
{
"tool": "search_messages",
"tags": [],
"reasons": {}
},
{
"tool": "send_attachment",
"tags": [
"external-sink"
],
"reasons": {
"external-sink": [
"parameter \"recipient\""
]
}
},
{
"tool": "send_group_attachment",
"tags": [],
"reasons": {}
},
{
"tool": "react_to_message",
"tags": [
"external-sink"
],
"reasons": {
"external-sink": [
"parameter \"recipient\""
]
}
},
{
"tool": "set_typing",
"tags": [
"external-sink"
],
"reasons": {
"external-sink": [
"parameter \"recipient\""
]
}
},
{
"tool": "get_profile",
"tags": [],
"reasons": {}
},
{
"tool": "block_contact",
"tags": [],
"reasons": {}
},
{
"tool": "unblock_contact",
"tags": [],
"reasons": {}
},
{
"tool": "remove_contact",
"tags": [],
"reasons": {}
},
{
"tool": "update_profile",
"tags": [],
"reasons": {}
},
{
"tool": "create_group",
"tags": [],
"reasons": {}
},
{
"tool": "join_group",
"tags": [],
"reasons": {}
},
{
"tool": "list_devices",
"tags": [],
"reasons": {}
},
{
"tool": "add_device",
"tags": [],
"reasons": {}
},
{
"tool": "remove_device",
"tags": [],
"reasons": {}
},
{
"tool": "get_own_number",
"tags": [],
"reasons": {}
},
{
"tool": "store_stats",
"tags": [],
"reasons": {}
},
{
"tool": "get_unread",
"tags": [],
"reasons": {}
},
{
"tool": "import_desktop",
"tags": [],
"reasons": {}
},
{
"tool": "sync_desktop",
"tags": [],
"reasons": {}
},
{
"tool": "list_conversations",
"tags": [],
"reasons": {}
},
{
"tool": "get_user_status",
"tags": [],
"reasons": {}
},
{
"tool": "send_sync_request",
"tags": [],
"reasons": {}
},
{
"tool": "delete_message",
"tags": [
"external-sink"
],
"reasons": {
"external-sink": [
"parameter \"recipient\""
]
}
},
{
"tool": "delete_group_message",
"tags": [],
"reasons": {}
},
{
"tool": "send_read_receipt",
"tags": [],
"reasons": {}
},
{
"tool": "update_contact",
"tags": [],
"reasons": {}
},
{
"tool": "update_group",
"tags": [],
"reasons": {}
},
{
"tool": "leave_group",
"tags": [],
"reasons": {}
},
{
"tool": "pin_message",
"tags": [
"external-sink"
],
"reasons": {
"external-sink": [
"parameter \"recipient\""
]
}
},
{
"tool": "unpin_message",
"tags": [
"external-sink"
],
"reasons": {
"external-sink": [
"parameter \"recipient\""
]
}
},
{
"tool": "admin_delete_message",
"tags": [],
"reasons": {}
},
{
"tool": "send_contacts_sync",
"tags": [],
"reasons": {}
},
{
"tool": "update_device",
"tags": [],
"reasons": {}
},
{
"tool": "mark_as_unread",
"tags": [],
"reasons": {}
},
{
"tool": "get_avatar",
"tags": [],
"reasons": {}
},
{
"tool": "send_message_request_response",
"tags": [
"external-sink"
],
"reasons": {
"external-sink": [
"keyword \"send_message\""
]
}
},
{
"tool": "create_poll",
"tags": [
"external-sink"
],
"reasons": {
"external-sink": [
"parameter \"recipient\""
]
}
},
{
"tool": "vote_poll",
"tags": [
"external-sink"
],
"reasons": {
"external-sink": [
"parameter \"recipient\""
]
}
},
{
"tool": "terminate_poll",
"tags": [
"external-sink"
],
"reasons": {
"external-sink": [
"parameter \"recipient\""
]
}
},
{
"tool": "set_expiration_timer",
"tags": [
"external-sink"
],
"reasons": {
"external-sink": [
"parameter \"recipient\""
]
}
},
{
"tool": "list_identities",
"tags": [],
"reasons": {}
},
{
"tool": "trust_identity",
"tags": [],
"reasons": {}
},
{
"tool": "clear_local_store",
"tags": [],
"reasons": {}
},
{
"tool": "delete_local_messages",
"tags": [
"external-sink"
],
"reasons": {
"external-sink": [
"parameter \"recipient\""
]
}
},
{
"tool": "export_messages",
"tags": [
"external-sink"
],
"reasons": {
"external-sink": [
"parameter \"recipient\""
]
}
},
{
"tool": "update_configuration",
"tags": [],
"reasons": {}
},
{
"tool": "list_sticker_packs",
"tags": [],
"reasons": {}
},
{
"tool": "add_sticker_pack",
"tags": [],
"reasons": {}
},
{
"tool": "send_sticker",
"tags": [
"external-sink"
],
"reasons": {
"external-sink": [
"parameter \"recipient\""
]
}
},
{
"tool": "send_group_sticker",
"tags": [],
"reasons": {}
},
{
"tool": "list_attachments",
"tags": [],
"reasons": {}
},
{
"tool": "get_attachment",
"tags": [],
"reasons": {}
},
{
"tool": "get_sticker",
"tags": [],
"reasons": {}
},
{
"tool": "upload_sticker_pack",
"tags": [],
"reasons": {}
},
{
"tool": "list_accounts",
"tags": [],
"reasons": {}
},
{
"tool": "update_account",
"tags": [],
"reasons": {}
},
{
"tool": "set_pin",
"tags": [],
"reasons": {}
},
{
"tool": "remove_pin",
"tags": [],
"reasons": {}
},
{
"tool": "start_change_number",
"tags": [],
"reasons": {}
},
{
"tool": "finish_change_number",
"tags": [],
"reasons": {}
},
{
"tool": "submit_rate_limit_challenge",
"tags": [
"external-sink"
],
"reasons": {
"external-sink": [
"keyword \"webhook\""
]
}
},
{
"tool": "prune_store",
"tags": [
"external-sink"
],
"reasons": {
"external-sink": [
"keyword \"webhook\""
]
}
},
{
"tool": "set_webhook",
"tags": [
"external-sink"
],
"reasons": {
"external-sink": [
"keyword \"webhook\""
]
}
},
{
"tool": "get_webhook",
"tags": [],
"reasons": {}
},
{
"tool": "find_contact",
"tags": [],
"reasons": {}
},
{
"tool": "schedule_message",
"tags": [
"external-sink"
],
"reasons": {
"external-sink": [
"parameter \"recipient\""
]
}
},
{
"tool": "list_scheduled_messages",
"tags": [],
"reasons": {}
},
{
"tool": "cancel_scheduled_message",
"tags": [],
"reasons": {}
},
{
"tool": "run_scheduled_messages",
"tags": [],
"reasons": {}
}
],
"surfaceDigest": "c0dd80582b684e46e2339fa24199c7b06413e27b31539d9a2bbcb36d212bf283",
"stats": {
"tools": 79,
"prompts": 0,
"resources": 0,
"findingsBySeverity": {
"critical": 0,
"high": 4,
"medium": 3,
"low": 0,
"info": 1
}
}
}