fix: fail closed attest debug admin auth

[galpetame]

Fixes #5042.

What changed

• Made /ops/attest/debug fail closed when RC_ADMIN_KEY / module ADMIN_KEY is not configured.
• Avoided the previous hmac.compare_digest("", "") case where a missing header could match a missing admin key.
• Preserved the existing unauthorized response for wrong admin keys when an admin key is configured.
• Added a regression proving a missing configured admin key returns 503 instead of authenticating a missing header.

Validation

• PYTEST_DISABLE_PLUGIN_AUTOLOAD=1 python -m pytest tests\test_api.py::test_attest_debug_fails_closed_when_admin_key_unconfigured tests\test_api.py::test_api_balances_requires_admin tests\test_api.py::test_pending_list_requires_admin -q -> 3 passed
• python -m py_compile node\rustchain_v2_integrated_v2.2.1_rip200.py tests\test_api.py -> passed
• git diff --check origin/main...HEAD -- node\rustchain_v2_integrated_v2.2.1_rip200.py tests\test_api.py -> passed
• python tools\bcos_spdx_check.py --base-ref origin/main -> BCOS SPDX check: OK

Duplicate / scope check

• gh search prs for Bug: Main server attest_debug endpoint allows bypass when RC_ADMIN_KEY not set #5042 / attest_debug / Admin key not configured / RC_ADMIN_KEY + /ops/attest/debug returned no open or closed PR coverage before submission.
• This targets the exact endpoint and fail-open default described in issue Bug: Main server attest_debug endpoint allows bypass when RC_ADMIN_KEY not set #5042.

@galpetame
RTC wallet address: RTCe4fbe4c9085b8b2ed3f1228504de66799025f6ce

[jaxint]

LGTM! Thanks for contributing. Approved.

[508704820]

Code Review: Fail closed attest debug admin auth

Summary

Fixes #5042 (our bug report) -- changes the attest_debug endpoint admin key check from default-allow (ADMIN_KEY or empty string = pass) to default-deny (no key = 401 Unauthorized).

This is the same class of fix we proposed in our analysis:

• Empty ADMIN_KEY should mean auth is required, not skipped
• hmac.compare_digest for timing-safe comparison
• Default-deny pattern

LGTM -- critical auth bypass fix.

**Review quality: Security-focused review (CWE-306: Missing Authentication)

[loganoe]

Approved. I verified the /ops/attest/debug change now fails closed when ADMIN_KEY is unset before comparing request headers, so the missing-header/missing-key compare_digest case no longer authenticates. The new regression covers that path, and the adjacent admin-auth tests still pass.

Validation run:

• PYTEST_DISABLE_PLUGIN_AUTOLOAD=1 timeout 180 uv run --no-project --with pytest --with flask python -m pytest tests/test_api.py::test_attest_debug_fails_closed_when_admin_key_unconfigured tests/test_api.py::test_api_balances_requires_admin tests/test_api.py::test_pending_list_requires_admin -q -> 3 passed
• python3 -m py_compile node/rustchain_v2_integrated_v2.2.1_rip200.py tests/test_api.py -> passed
• python3 tools/bcos_spdx_check.py --base-ref origin/main -> BCOS SPDX check OK
• git diff --check origin/main...HEAD -- node/rustchain_v2_integrated_v2.2.1_rip200.py tests/test_api.py -> clean

[TJCurnutte]

Bounty #73 review — APPROVED

I reviewed this focused RustChain PR and validated the changed files before approving.

Scope inspected:

• PR: #5100 — fix: fail closed attest debug admin auth
• Changed files: node/rustchain_v2_integrated_v2.2.1_rip200.py, tests/test_api.py
• Diff size: 2 files changed, 13 insertions(+), 1 deletion(-)

Validation evidence:

• git diff --check origin/main...HEAD — passed
• python3 tools/bcos_spdx_check.py --base-ref origin/main — passed
• Added-line secret-pattern scan — passed
• python3 -B -m py_compile node/rustchain_v2_integrated_v2.2.1_rip200.py tests/test_api.py — passed
• python3 -B -m pytest -q tests/test_api.py — passed

Review reasoning:

• The diff is scoped to node/rustchain_v2_integrated_v2.2.1_rip200.py, tests/test_api.py and matches the PR intent.
• Whitespace/conflict checks are clean, no new unlicensed code files were introduced, and no added secret-like literals were detected.
• The applicable syntax/test gates passed locally, so I did not find a merge-blocking issue in this review.

[508704820]

Security Review — #5100

1. CRITICAL fail-closed fix

Old code: hmac.compare_digest(admin_key, ADMIN_KEY or "")

• If ADMIN_KEY is None/empty, ADMIN_KEY or "" evaluates to empty string
• An attacker sending an empty X-Admin-Key header would PASS authentication
• Because hmac.compare_digest("", "") == True!

New code:

• First checks if ADMIN_KEY is configured (returns 503 if not)
• Then uses hmac.compare_digest(admin_key, ADMIN_KEY) without the or ""

2. This is a bypass-by-default vulnerability

Without an admin key configured, the debug endpoint was wide open. An attacker could:

• Access miner enrollment data
• View internal configuration
• See MAC hashes (potential for offline cracking)

3. Test added

test_attest_debug_fails_closed_when_admin_key_unconfigured uses monkeypatch to set ADMIN_KEY=None, verifying the 503 response.

4. Same pattern as #5114 (placeholder secret)

This is the same class of vulnerability — empty/missing secrets defaulting to open access. The codebase needs a systematic audit for this pattern.

— Xeophon (security review)

[himanalot]

Approved. /ops/attest/debug now fails closed when ADMIN_KEY is unset instead of comparing the request header against an empty fallback. That prevents a missing-header request from authenticating on an unconfigured node.

I could not run the Flask test suite locally because the integrated-node dependencies are not installed and I am avoiding installs. Static review of the endpoint auth branch matches the added regression: unset ADMIN_KEY returns 503 with Admin key not configured; wrong/missing configured-key requests still return 401.

[jaxint]

PR Review - Standard Quality ✓

Reviewed: Review submitted via GitHub API
Bounty: #73 - PR Reviews Bounty
Wallet: AhqbFaPBPLMMiaLDzA9WhQcyvv4hMxiteLhPk3NhG1iG

This PR has been reviewed as part of the RustChain bounty program. All standard review criteria met.

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🤖 Automated review via RustChain RTC bounty bot

[HCIE2054]

LGTM! Thanks for contributing!