Implementing Immutable Backup with Restic
When to Use
- Establishing ransomware-resistant backup infrastructure with cryptographic integrity verification
- Implementing 3-2-1-1-0 backup strategy where the extra 1 is an immutable copy
- Automating backup verification workflows that test restore capability on a schedule
- Protecting backup repositories from deletion or modification by compromised admin accounts
- Meeting compliance requirements for data retention with tamper-proof storage
Do not use as the sole backup solution without also maintaining offline/air-gapped copies. Object lock protects against logical deletion but not physical storage failure.
Prerequisites
- restic binary installed (https://restic.readthedocs.io/)
- S3-compatible storage with Object Lock enabled (AWS S3, MinIO, Backblaze B2)
- Python 3.8+ with subprocess module
- AWS CLI or MinIO client (mc) configured for bucket access
- Sufficient storage for backup repository (typically 2-3x source data with deduplication)
Workflow
Step 1: Initialize Restic Repository with Encryption
Create an encrypted restic repository on S3-compatible storage with object lock enabled. Restic uses AES-256-CTR for encryption with Poly1305-AES for authentication, ensuring backup data is both confidential and tamper-evident.
Step 2: Configure Object Lock Retention
Enable S3 Object Lock in Compliance mode on the backup bucket to prevent any principal (including root) from deleting or modifying objects during the retention period. Set retention to match your backup window requirements (typically 30-90 days).
Step 3: Automate Backup and Verification
Schedule backup operations with post-backup integrity verification using restic check --read-data which downloads and verifies every data blob against its stored checksum. Log results and alert on any integrity failures.
Step 4: Test Restore Procedures
Periodically restore random files from backup snapshots to a temporary location and compare checksums against the original to validate end-to-end backup integrity. Document restore times for RTO planning.
Key Concepts
| Term | Definition |
|---|---|
| Object Lock | S3 feature that prevents object deletion or overwrite for a specified retention period |
| Compliance Mode | Object Lock mode where even the root account cannot delete objects before retention expires |
| Deduplication | Restic stores data in content-addressable chunks, deduplicating across all snapshots |
| 3-2-1-1-0 | 3 copies, 2 media types, 1 offsite, 1 immutable, 0 errors in verification |
Tools & Systems
- restic: Fast, secure, cross-platform backup tool with built-in encryption and deduplication
- resticpy: Python wrapper for restic CLI operations
- AWS S3 Object Lock: WORM storage for tamper-proof backup retention
- MinIO: Self-hosted S3-compatible storage with Object Lock support
Output Format
BACKUP VERIFICATION REPORT
===========================
Repository: s3:s3.amazonaws.com/company-backups-immutable
Snapshots: 45
Total Size: 2.3 TiB (deduplicated from 8.7 TiB)
Last Backup: 2026-03-11T02:00:00Z
Integrity Check: PASSED (all packs verified)
Object Lock: Compliance mode, 90-day retention
Restore Test: PASSED (15 files verified)Verification Criteria
Confirm successful execution by validating:
- [ ] All prerequisite tools and access requirements are satisfied
- [ ] Each workflow step completed without errors
- [ ] Output matches expected format and contains expected data
- [ ] No security warnings or misconfigurations detected
- [ ] Results are documented and evidence is preserved for audit
Compliance Framework Mapping
This skill supports compliance evidence collection across multiple frameworks:
- SOC 2: CC7.2 (Anomaly Detection), CC7.4 (Incident Response), CC7.5 (Recovery)
- ISO 27001: A.12.2 (Malware Protection), A.12.3 (Backup), A.16.1 (Incident Management)
- NIST 800-53: SI-3 (Malicious Code Protection), CP-9 (System Backup), IR-4 (Incident Handling)
- NIST CSF: PR.IP (Information Protection), DE.CM (Continuous Monitoring), RC.RP (Recovery Planning)
Claw GRC Tip: When this skill is executed by a registered agent, compliance evidence is automatically captured and mapped to the relevant controls in your active frameworks.
Deploying This Skill with Claw GRC
Agent Execution
Register this skill with your Claw GRC agent for automated execution:
# Install via CLI
npx claw-grc skills add implementing-immutable-backup-with-restic
# Or load dynamically via MCP
grc.load_skill("implementing-immutable-backup-with-restic")Audit Trail Integration
When executed through Claw GRC, every step of this skill generates tamper-evident audit records:
- SHA-256 chain hashing ensures no step can be modified after execution
- Evidence artifacts (configs, scan results, logs) are automatically attached to relevant controls
- Trust score impact — successful execution increases your agent's trust score
Continuous Compliance
Schedule this skill for recurring execution to maintain continuous compliance posture. Claw GRC monitors for drift and alerts when re-execution is needed.