# Risk Bundles (Airgap)

Risk bundles package vulnerability intelligence data for offline/air-gapped environments. They provide deterministic, signed archives containing provider datasets (CISA KEV, FIRST EPSS, OSV) that can be verified and imported without network connectivity.

## Bundle Structure

A risk bundle is a gzip-compressed tar archive (`risk-bundle.tar.gz`) with the following structure:

```
risk-bundle.tar.gz
├── manifests/
│   └── provider-manifest.json      # Bundle metadata and provider entries
├── providers/
│   ├── cisa-kev/
│   │   └── snapshot                # CISA Known Exploited Vulnerabilities JSON
│   ├── first-epss/
│   │   └── snapshot                # FIRST EPSS scores CSV/JSON
│   └── osv/                        # (optional) OpenSSF OSV bulk JSON
│       └── snapshot
└── signatures/
    └── provider-manifest.dsse      # DSSE envelope for manifest
```

## Provider Manifest

The `provider-manifest.json` contains bundle metadata and per-provider entries:

```json
{
  "version": "1.0.0",
  "bundleId": "risk-bundle-20241211-120000",
  "createdAt": "2024-12-11T12:00:00Z",
  "inputsHash": "sha256:abc123...",
  "providers": [
    {
      "providerId": "cisa-kev",
      "digest": "sha256:def456...",
      "snapshotDate": "2024-12-11T00:00:00Z",
      "optional": false
    },
    {
      "providerId": "first-epss",
      "digest": "sha256:789abc...",
      "snapshotDate": "2024-12-11T00:00:00Z",
      "optional": true
    }
  ]
}
```

| Field | Description |
|-------|-------------|
| `version` | Manifest schema version (currently `1.0.0`) |
| `bundleId` | Unique identifier for this bundle |
| `createdAt` | ISO-8601 UTC timestamp of bundle creation |
| `inputsHash` | SHA-256 hash of concatenated provider digests (deterministic ordering) |
| `providers[]` | Array of provider entries sorted by `providerId` |

### Provider Entry Fields

| Field | Description |
|-------|-------------|
| `providerId` | Provider identifier (`cisa-kev`, `first-epss`, `osv`) |
| `digest` | SHA-256 hash of snapshot file (`sha256:<hex>`) |
| `snapshotDate` | ISO-8601 timestamp of provider data snapshot |
| `optional` | Whether provider is required for bundle validity |

## Provider Catalog

| Provider | Source | Coverage | Refresh | Required |
|----------|--------|----------|---------|----------|
| `cisa-kev` | CISA Known Exploited Vulnerabilities | Exploited CVEs with KEV flag | Daily | Yes |
| `first-epss` | FIRST EPSS scores | Exploitation probability per CVE | Daily | No |
| `osv` | OpenSSF OSV | OSS advisories with affected ranges | Weekly | No (opt-in) |

## Building Risk Bundles

### Using the Export Worker

The ExportCenter worker can build risk bundles via the `stella export risk-bundle` job:

```bash
# Build bundle with default providers (CISA KEV + EPSS)
stella export risk-bundle --output /path/to/output

# Include OSV providers (larger bundle)
stella export risk-bundle --output /path/to/output --include-osv

# Build with specific bundle ID
stella export risk-bundle --output /path/to/output --bundle-id "custom-bundle-id"
```

### Using the CI Build Script

For CI pipelines and deterministic testing, use the shell scripts:

```bash
# Build fixture bundle for CI testing (deterministic)
ops/devops/risk-bundle/build-bundle.sh --output /tmp/bundle --fixtures-only

# Build with OSV
ops/devops/risk-bundle/build-bundle.sh --output /tmp/bundle --fixtures-only --include-osv

# Build with custom bundle ID
ops/devops/risk-bundle/build-bundle.sh --output /tmp/bundle --fixtures-only --bundle-id "ci-test-bundle"
```

### Build Script Options

| Option | Description |
|--------|-------------|
| `--output <dir>` | Output directory for bundle artifacts (required) |
| `--fixtures-only` | Use fixture data instead of live provider downloads |
| `--include-osv` | Include OSV providers (increases bundle size) |
| `--bundle-id <id>` | Custom bundle ID (default: auto-generated with timestamp) |

### Build Outputs

After building, the output directory contains:

```
output/
├── risk-bundle.tar.gz          # The bundle archive
├── risk-bundle.tar.gz.sha256   # SHA-256 checksum
└── manifest.json               # Copy of provider-manifest.json
```

## Verifying Risk Bundles

### Using the CLI

```bash
# Basic verification
stella risk bundle verify --bundle-path ./risk-bundle.tar.gz

# With detached signature
stella risk bundle verify --bundle-path ./risk-bundle.tar.gz --signature-path ./bundle.sig

# Check Sigstore Rekor transparency log
stella risk bundle verify --bundle-path ./risk-bundle.tar.gz --check-rekor

# JSON output for automation
stella risk bundle verify --bundle-path ./risk-bundle.tar.gz --json

# Verbose output with warnings
stella risk bundle verify --bundle-path ./risk-bundle.tar.gz --verbose
```

### CLI Options

| Option | Description |
|--------|-------------|
| `--bundle-path, -b` | Path to risk bundle file (required) |
| `--signature-path, -s` | Path to detached signature file |
| `--check-rekor` | Verify transparency log entry in Sigstore Rekor |
| `--json` | Output results as JSON |
| `--tenant` | Tenant context for verification |
| `--verbose` | Show detailed output including warnings |

### Using the Verification Script

For offline/air-gap verification without the CLI:

```bash
# Basic verification
ops/devops/risk-bundle/verify-bundle.sh /path/to/risk-bundle.tar.gz

# With detached signature
ops/devops/risk-bundle/verify-bundle.sh /path/to/risk-bundle.tar.gz --signature /path/to/bundle.sig

# Strict mode (warnings are errors)
ops/devops/risk-bundle/verify-bundle.sh /path/to/risk-bundle.tar.gz --strict

# JSON output
ops/devops/risk-bundle/verify-bundle.sh /path/to/risk-bundle.tar.gz --json
```

### Verification Steps

The verification process performs these checks:

1. **Archive integrity** - Bundle is a valid tar.gz archive
2. **Structure validation** - Required files present (`manifests/provider-manifest.json`)
3. **Manifest parsing** - Valid JSON with required fields (`bundleId`, `version`, `providers`)
4. **Provider hash verification** - Each provider snapshot matches its declared digest
5. **Mandatory provider check** - `cisa-kev` must be present and valid
6. **DSSE signature validation** - Manifest signature verified (if present)
7. **Detached signature** - Bundle archive signature verified (if provided)

### Exit Codes

| Code | Meaning |
|------|---------|
| 0 | Bundle is valid |
| 1 | Bundle is invalid or verification failed |
| 2 | Input error (missing file, bad arguments) |

### JSON Output Format

```json
{
  "valid": true,
  "bundleId": "risk-bundle-20241211-120000",
  "version": "1.0.0",
  "providerCount": 2,
  "mandatoryProviderFound": true,
  "errorCount": 0,
  "warningCount": 1,
  "errors": [],
  "warnings": ["Optional provider not found: osv"]
}
```

## Importing Risk Bundles

### Prerequisites

1. Verify the bundle before import (see above)
2. Ensure the target system has sufficient storage
3. Back up existing provider data if replacing

### Import Steps

1. **Transfer the bundle** to the air-gapped environment via approved media
2. **Verify the bundle** using the CLI or verification script
3. **Extract to staging**:
   ```bash
   mkdir -p /staging/risk-bundle
   tar -xzf risk-bundle.tar.gz -C /staging/risk-bundle
   ```
4. **Validate provider data**:
   ```bash
   # Verify individual provider hashes
   sha256sum /staging/risk-bundle/providers/cisa-kev/snapshot
   sha256sum /staging/risk-bundle/providers/first-epss/snapshot
   ```
5. **Import into Concelier**:
   ```bash
   stella concelier import-risk-bundle --path /staging/risk-bundle
   ```

### Error Handling

| Error | Cause | Resolution |
|-------|-------|------------|
| "Bundle is not a valid tar.gz archive" | Corrupted download/transfer | Re-download and verify checksum |
| "Missing required file: manifests/provider-manifest.json" | Incomplete bundle | Rebuild bundle |
| "Missing mandatory provider: cisa-kev" | KEV snapshot missing | Rebuild with valid provider data |
| "Hash mismatch: cisa-kev" | Corrupted provider data | Re-download provider snapshot |
| "DSSE signature validation failed" | Tampered manifest | Investigate chain of custody |

## CI/CD Integration

### GitHub Actions / Gitea Workflow

The `.gitea/workflows/risk-bundle-ci.yml` workflow:

1. **Build job**: Compiles RiskBundles library, runs tests, builds fixture bundle
2. **Offline kit job**: Packages bundle for offline kit distribution
3. **Publish checksums job**: Publishes checksums to artifact store (main branch only)

```yaml
# Trigger manually or on push to relevant paths
on:
  push:
    paths:
      - 'src/ExportCenter/StellaOps.ExportCenter.RiskBundles/**'
      - 'ops/devops/risk-bundle/**'
  workflow_dispatch:
    inputs:
      include_osv:
        type: boolean
        default: false
```

### Offline Kit Integration

Risk bundles are included in the Offline Update Kit:

```
offline-kit/
└── risk-bundles/
    ├── risk-bundle.tar.gz
    ├── risk-bundle.tar.gz.sha256
    ├── manifest.json
    ├── checksums.txt
    └── kit-manifest.json
```

The `kit-manifest.json` provides metadata for offline kit consumers:

```json
{
  "component": "risk-bundle",
  "version": "20241211-120000",
  "files": [
    {"path": "risk-bundle.tar.gz", "checksum_file": "risk-bundle.tar.gz.sha256"},
    {"path": "manifest.json", "checksum_file": "manifest.json.sha256"}
  ],
  "verification": {
    "checksums": "checksums.txt",
    "signature": "risk-bundle.tar.gz.sig"
  }
}
```

## Signing and Trust

### DSSE Manifest Signature

The `signatures/provider-manifest.dsse` file contains a Dead Simple Signing Envelope:

```json
{
  "payloadType": "application/vnd.stellaops.risk-bundle.manifest+json",
  "payload": "<base64-encoded-manifest>",
  "signatures": [
    {
      "keyid": "risk-bundle-signing-key",
      "sig": "<signature>"
    }
  ]
}
```

### Offline Trust Roots

For air-gapped verification, include public keys in the bundle:

```
signatures/
├── provider-manifest.dsse
└── pubkeys/
    └── <tenant>.pem
```

### Sigstore/Rekor Integration

When `--check-rekor` is specified, verification queries the Sigstore Rekor transparency log to confirm the bundle was published to the public ledger.

## Determinism Checklist

Risk bundles are designed for reproducible builds:

- [x] Fixed timestamps for tar entries (`--mtime="@<epoch>"`)
- [x] Sorted file ordering (`--sort=name`)
- [x] Numeric owner/group (`--owner=0 --group=0 --numeric-owner`)
- [x] Deterministic gzip compression (`gzip -n`)
- [x] Providers sorted by `providerId` in manifest
- [x] Files sorted lexicographically in bundle
- [x] UTF-8 canonical paths
- [x] ISO-8601 UTC timestamps

## Troubleshooting

### Common Issues

**Q: Bundle verification fails with "jq not available"**

A: The verification script uses `jq` for JSON parsing. Install it or use the CLI (`stella risk bundle verify`) which has built-in JSON support.

**Q: Hash mismatch after transfer**

A: Binary transfers can corrupt files. Use checksums:
```bash
# On source system
sha256sum risk-bundle.tar.gz > checksum.txt

# On target system
sha256sum -c checksum.txt
```

**Q: "Optional provider not found" warning**

A: This is informational. Optional providers (EPSS, OSV) enhance risk analysis but aren't required. Use `--strict` if you want to enforce their presence.

**Q: DSSE signature validation fails in air-gap**

A: Ensure the offline trust root is configured:
```bash
stella config set risk-bundle.trust-root /path/to/pubkey.pem
```

## Related Documentation

- [Offline Update Kit](../24_OFFLINE_KIT.md) - Complete offline kit documentation
- [Mirror Bundles](./mirror-bundles.md) - OCI artifact bundles for air-gap
- [Provider Matrix](../modules/export-center/operations/risk-bundle-provider-matrix.md) - Detailed provider specifications
- [ExportCenter Architecture](../modules/export-center/architecture.md) - Export service design