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Rule Reference

SEC664lintai-ai-securitystablejsonwarn

MCP config: insecure chmod

MCP configuration command performs an insecure permission change

Provider
lintai-ai-security
Surface
json
Scope
per_file
Tier
stable
Severity
warn
Confidence
high
Detection
structural
Remediation
message_only

Activation Model

Preset Membership

This rule is part of the builtin activation graph through these preset memberships.

basemembership
mcpmembership

Lifecycle

Stable Lifecycle Contract

State

stable_gated

Graduation rationale

Checks committed MCP launch paths for explicit insecure chmod payloads.

Deterministic signal basis

JsonSignals command-plus-args analysis over ArtifactKind::McpConfig for `chmod 777`, `chmod 0777`, or symbolic world-writable modes such as `a+rwx`.

Malicious corpus
mcp-command-privilege-escalation-payloads
Benign corpus
mcp-safe-basic
structured evidence required remediation reviewed
Canonical note

Structural stable rule intended as a high-precision check with deterministic evidence.

Nearby Signals

Related Rules

SEC301MCP config: shell trampolineMCP configuration shells out through sh -c or bash -cjsonstable
SEC302Config: insecure HTTP endpointConfiguration contains an insecure http:// endpointjsonstable
SEC303MCP config: credential env passthroughMCP configuration passes through credential environment variablesjsonstable
SEC304Config: TLS verification disabledConfiguration disables TLS or certificate verificationjsonstable
SEC305Config: hardcoded auth materialConfiguration embeds static authentication material in a connection or auth valuejsonstable
SEC309Config: literal secrets in configConfiguration commits literal secret material in env, auth, or header valuesjsonstable

Why It Matters ​

An MCP launcher that runs chmod 777-style commands can weaken host file protections through shared committed config.

What Triggers ​

SEC664 matches MCP command definitions that run insecure chmod modes such as 777, 0777, or symbolic world-writable modes like a+rwx.

False Positives ​

Quick local setup scripts sometimes do this, but shared MCP config should not silently broaden host write access.

Remediation ​

Replace broad chmod modes with the minimum required permissions and keep risky host permission changes out of shared MCP launch paths.