STIG compliance is non-negotiable for DoD contracts. A single CAT I finding can halt your ATO process. This guide covers the essential knowledge for navigating STIG requirements from initial implementation to continuous monitoring.
What are DISA STIGs?
Security Technical Implementation Guides (STIGs) are configuration standards developed by the Defense Information Systems Agency (DISA). They contain technical guidance for "locking down" or hardening information systems and software that might otherwise be vulnerable to attack.
Unlike high-level frameworks like NIST 800-53, STIGs are prescriptive—they tell you exactly what settings to configure, what services to disable, and what audit policies to enable.
STIG Categories
DISA publishes STIGs for hundreds of products across multiple categories:
| Category | Examples | Key Concerns |
|---|---|---|
| Operating Systems | Windows Server, RHEL, Ubuntu | Hardening, logging, access control |
| Databases | PostgreSQL, Oracle, SQL Server | Encryption, authentication, auditing |
| Web Servers | Apache, Nginx, IIS | TLS configuration, headers, logging |
| Network Devices | Cisco, Palo Alto, Juniper | ACLs, management access, firmware |
| Applications | Docker, Kubernetes, browsers | Container security, sandboxing |
Finding Severity Categories
Every STIG rule is assigned a Category (CAT) rating based on potential impact:
Directly allows unauthorized access, denial of service, or immediate security compromise. Must be remediated immediately. No exceptions for ATO.
Degrades security measures or may allow access if combined with other vulnerabilities. Requires remediation with documented POA&M timeline.
Results in minor degradation of security. Should be addressed but may be accepted with risk acknowledgment.
STIG Compliance Workflow
1. Identify Applicable STIGs
Start by inventorying all components in your system and mapping them to STIG IDs. DISA's STIG Library contains the authoritative list.
2. Download and Review
STIGs are distributed in multiple formats:
- XCCDF/SCAP — Machine-readable for automated scanning
- Checklist (CKL) — Manual verification in STIG Viewer
- PDF — Human-readable documentation
3. Baseline Assessment
Run an initial scan using SCAP tools to establish your compliance baseline:
# Using OpenSCAP on RHEL
oscap xccdf eval \
--profile xccdf_mil.disa.stig_profile_MAC-1_Classified \
--results results.xml \
--report report.html \
/path/to/stig-rhel8-xccdf.xml4. Remediation
Address findings systematically, starting with CAT I. For each finding:
- Understand the vulnerability and why the setting matters
- Test the remediation in a non-production environment
- Document the change with before/after evidence
- Apply to production during approved change windows
5. Continuous Monitoring
STIG compliance isn't one-time. Implement automated scanning on a schedule (typically weekly or daily) to detect configuration drift.
STIG Compliance in Air-Gapped Environments
For air-gapped systems, STIG compliance presents unique challenges:
- No network-based scanning — Use local SCAP tools or manual checklists
- Offline STIG updates — Download STIGs via secure media transfer
- Audit log extraction — Establish secure procedures for retrieving compliance evidence
- Configuration management — Version-controlled baselines prevent drift
Common STIG Hardening Areas
Authentication & Access
- Password complexity and rotation policies
- Account lockout thresholds
- Multi-factor authentication requirements
- Privileged access controls (CAC/PIV enforcement)
Audit & Logging
- Comprehensive audit policy configuration
- Log retention requirements (typically 1 year)
- Centralized log aggregation
- Tamper-evident log storage
Network Security
- TLS 1.2/1.3 only, no legacy protocols
- FIPS 140-2 validated cryptography
- Firewall rules and network segmentation
- SSH hardening (no password auth, key-only)
Tools for STIG Compliance
| Tool | Type | Best For |
|---|---|---|
| DISA SCAP Compliance Checker (SCC) | Free (DoD) | Official DoD scanning |
| STIG Viewer | Free (DoD) | Manual checklist management |
| OpenSCAP | Open Source | Linux automation |
| Tenable Nessus | Commercial | Enterprise scanning |
| Ansible Lockdown | Open Source | Automated remediation |
Alterra's STIG-Ready Approach
At Alterra Solutions, every system we deliver is pre-hardened to applicable STIG baselines. Our deployment packages include:
- Complete SCAP scan results with zero CAT I findings
- Documented exceptions with risk acceptance rationale
- Automated remediation playbooks for configuration drift
- Air-gap compatible update procedures
For classified environments, we provide scan results in formats suitable for direct inclusion in ATO documentation packages.
Need help turning STIG findings into real hardening work?
Our DISA STIG service covers baseline review, remediation sequencing, hardening support, and evidence structure for regulated and defense environments.