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Rule Reference

SEC312lintai-ai-securitystablemarkdownwarn

Markdown: private key material

Markdown contains committed private key material

Provider
lintai-ai-security
Surface
markdown
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
skillsmembership

Lifecycle

Stable Lifecycle Contract

State

stable_gated

Graduation rationale

Matches explicit committed private-key PEM markers inside agent markdown surfaces.

Deterministic signal basis

MarkdownSignals private-key marker observation across parsed markdown regions excluding placeholder examples.

Malicious corpus
skill-private-key-pem
Benign corpus
skill-public-key-pem-safe
structured evidence required remediation reviewed
Canonical note

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

Nearby Signals

Related Rules

SEC352AI markdown: unscoped Bash tool grantAI-native markdown frontmatter grants unscoped Bash tool accessmarkdownstable
SEC417AI markdown: unpinned pip git installAI-native markdown installs Python packages from an unpinned `git+https://` sourcemarkdownstable
SEC428AI markdown: unsafe Read path grantAI-native markdown frontmatter grants `Read(...)` over an unsafe repo-external pathmarkdownstable
SEC429AI markdown: unsafe Write path grantAI-native markdown frontmatter grants `Write(...)` over an unsafe repo-external pathmarkdownstable
SEC430AI markdown: unsafe Edit path grantAI-native markdown frontmatter grants `Edit(...)` over an unsafe repo-external pathmarkdownstable
SEC431AI markdown: unsafe Glob path grantAI-native markdown frontmatter grants `Glob(...)` over an unsafe repo-external pathmarkdownstable

Why It Matters ​

SEC312 flags markdown that contains committed private key material in PEM form.

Unlike general secret-pattern heuristics, this rule looks for real PEM private-key markers. That makes it a much stronger signal that sensitive key material has been committed into documentation or examples.

What Triggers ​

SEC312 triggers when markdown contains a PEM-style private key marker such as:

  • -----BEGIN RSA PRIVATE KEY-----
  • -----BEGIN OPENSSH PRIVATE KEY-----
  • -----BEGIN EC PRIVATE KEY-----
  • -----BEGIN PRIVATE KEY-----

Example that triggers:

pem
-----BEGIN OPENSSH PRIVATE KEY-----
...
-----END OPENSSH PRIVATE KEY-----

Examples that stay clean:

  • public key PEM blocks such as -----BEGIN PUBLIC KEY-----
  • search-string literals like memory search "BEGIN RSA PRIVATE KEY"
  • obviously redacted placeholders such as example private key

False Positives ​

This is one of the cleaner markdown security signals because it requires a real PEM private-key marker instead of a generic substring. Recent fixes explicitly stopped matching search-string literals like "BEGIN RSA PRIVATE KEY" without PEM framing.

Remediation ​

Remove the private key from the repository, rotate the affected credential if it was real, and replace the example with a redacted placeholder or non-sensitive public material.