CIS Benchmark for Cisco Routers: What It Is and How to Meet It
The CIS Benchmark for Cisco IOS is the gold standard for router security hardening. If you manage Cisco routers and need to prove compliance — or just want to close real attack surface — this guide explains exactly what the benchmark covers and how to measure your posture against it.
What Is the CIS Benchmark?
The Center for Internet Security (CIS) is a nonprofit organization that publishes consensus-based security configuration guidelines for operating systems, cloud platforms, databases, and network devices. The CIS Benchmark for Cisco IOS is the document that defines what a properly hardened Cisco router configuration looks like.
Unlike vendor documentation that describes what features can be configured, the CIS Benchmark specifies what must be configured for a router to be considered secure. Each control includes a rationale, audit procedure, and remediation command — making it one of the most actionable hardening references available.
The benchmark exists in versions for Cisco IOS and Cisco IOS-XE. While the underlying security principles are the same, some commands differ between platforms. Always verify you are checking against the correct version for your router’s operating system.
Level 1 vs Level 2 Explained
Every CIS Benchmark organizes controls into two profile levels. Understanding the difference helps you prioritize your hardening effort and avoid over-engineering in low-risk environments.
Base Security Profile
Level 1 controls are the minimum recommended settings for any Cisco router in any environment. They are designed to have little or no operational impact and represent basic hygiene: disabling unnecessary services, enforcing strong authentication, enabling logging, and removing default credentials. Every router should meet Level 1 without exception.
High-Security Profile
Level 2 controls are intended for environments with elevated security requirements — financial institutions, healthcare networks, government infrastructure, or anywhere sensitive data traverses the router. These controls may require additional planning because some (like strict Control Plane Policing configurations) can affect performance or disrupt routing if applied incorrectly.
For most enterprise environments, achieving full Level 1 compliance and targeting the most operationally safe Level 2 controls is the practical goal. A gap analysis against both levels gives you a clear picture of where you stand.
The 8 Control Domains
The CIS Benchmark for Cisco IOS organizes controls into eight domains. Each domain targets a specific attack surface. The table below summarizes each domain and the approximate number of controls it contains.
| Domain | What It Covers | Approx. Controls |
|---|---|---|
| Management Plane | SSH, Telnet, console/VTY access, banner messages | 18–22 |
| Authentication, Authorization & Accounting | AAA framework, RADIUS/TACACS+, local accounts | 10–14 |
| Password Management | Enable secret, service password-encryption, password complexity | 6–9 |
| Routing Protocols | OSPF/EIGRP/BGP authentication, passive interfaces | 8–12 |
| Network Services | CDP, LLDP, IP source routing, proxy ARP, DHCP, Finger | 14–18 |
| NTP | NTP authentication, trusted sources, version | 4–6 |
| Logging | Syslog, buffered logging, timestamps, log severity | 6–8 |
| Control Plane | CoPP, IP CEF, uRPF, TCP intercept | 5–8 |
Key Controls You Must Meet
While every control in the benchmark matters, the following are the ones most commonly failed during audits and carry the highest risk when missing.
1. Disable Telnet — Use SSH Version 2 Only
Telnet transmits all data — including passwords — in plaintext. Any router accessible via Telnet is vulnerable to credential theft via packet capture. The CIS Benchmark requires SSH version 2 and the explicit disabling of Telnet on all VTY lines.
ip ssh version 2
line vty 0 4
transport input sshVerify: show ip ssh — confirm SSH version 2 is active
2. Enable Service Password-Encryption
Without this setting, passwords stored in the running configuration appear in plaintext. While the encryption is weak (Type 7), it prevents casual exposure and is a required baseline control.
service password-encryptionVerify: No plaintext passwords visible in show running-config
3. Require Enable Secret (Not Enable Password)
The enable password command uses weak reversible encryption. The CIS Benchmark requires enable secret which uses MD5 (or stronger on newer IOS versions). Both commands should never coexist on the same device.
enable secret 0 [strong-password]
no enable password4. Configure AAA Authentication
Local usernames and passwords are a fallback, not a primary auth mechanism. The CIS Benchmark requires AAA to be enabled and configured with a named authentication list applied to all management interfaces. This supports centralized authentication via TACACS+ or RADIUS.
aaa new-model
aaa authentication login default group tacacs+ local
aaa authorization exec default group tacacs+ local5. Disable Unnecessary Services
Cisco IOS enables several services by default that are unnecessary in modern networks and expand the attack surface. The following should be explicitly disabled on all routers.
no service finger
no service pad
no service udp-small-servers
no service tcp-small-servers
no ip bootp server
no ip http server
no ip http secure-server
no cdp run6. Configure Login Banners
A legal warning banner must appear before login on all access methods. The banner must state that access is restricted to authorized users. Without this, prosecution of unauthorized access attempts can be legally complicated in some jurisdictions.
banner login ^
UNAUTHORIZED ACCESS TO THIS DEVICE IS PROHIBITED.
All activity is monitored and recorded.
^7. Enable Logging with Timestamps
Logging is useless for incident response if timestamps are absent or imprecise. The benchmark requires buffered logging at a minimum severity of informational, with datetime timestamps including milliseconds.
service timestamps log datetime msec show-timezone localtime
logging buffered 16384 informational
logging trap informational8. Configure Control Plane Policing (CoPP)
CoPP protects the router’s control plane CPU from being overwhelmed by excessive traffic — whether from a DDoS attack or a misconfigured network device. It classifies traffic destined for the router itself and applies rate limits by traffic type.
policy-map COPP-POLICY
class ICMP-CLASS
police rate 8000 bps
class MANAGEMENT-CLASS
police rate 64000 bps
control-plane
service-policy input COPP-POLICYCheck Your Router Against CIS Benchmark Controls
Paste your Cisco IOS or IOS-XE running config and get an instant compliance report. Free, no login, nothing leaves your browser.
Run Free CIS Audit →Which Compliance Frameworks Require CIS Benchmark
The CIS Benchmark is referenced directly or by implication in several major compliance frameworks. If your organization is subject to any of the following, achieving CIS Benchmark compliance on your network devices is likely a control requirement — not just a best practice.
PCI DSS: Requirement 2.2 states that system components must be configured according to industry-accepted hardening standards. CIS Benchmarks are explicitly cited as acceptable standards in the PCI DSS guidance documentation. Any router that handles cardholder data or resides in the cardholder data environment must meet this requirement.
HIPAA: The Security Rule (45 CFR § 164.312) requires covered entities to implement technical security measures to guard against unauthorized access. CIS Benchmark compliance demonstrates due diligence in hardening network infrastructure that handles PHI.
SOC 2 (CC6.1): SOC 2 requires organizations to implement logical access controls and infrastructure security. Auditors commonly look for documented hardening standards and evidence of compliance. CIS Benchmarks provide both the standard and the audit procedure.
NIST SP 800-53: Controls like CM-6 (Configuration Settings) and CM-7 (Least Functionality) map directly to CIS Benchmark requirements. Organizations pursuing FedRAMP authorization or following NIST frameworks will find CIS Benchmark a natural fit.
ISO/IEC 27001: Annex A control A.12.6 (Technical Vulnerability Management) and A.13.1 (Network Security Management) are addressed by CIS Benchmark compliance. ISO auditors accept CIS Benchmarks as evidence of systematic hardening.
How to Audit Against the CIS Benchmark
There are two approaches to checking a Cisco router against the CIS Benchmark: manual review and automated scanning. In practice, a combination of both gives the most complete picture.
Manual Review
Download the CIS Benchmark PDF for Cisco IOS from the CIS website (free registration required). The document lists each control with an audit procedure — typically a specific show command and what the output should contain. Work through each control systematically, noting pass/fail status in a spreadsheet.
Manual review is thorough but time-consuming for a full benchmark sweep. A single device can take 2–4 hours for someone unfamiliar with the benchmark. It also depends heavily on the reviewer’s knowledge of IOS syntax and what each command output means.
Automated Audit Tool
A free Cisco router audit tool can check a running configuration against CIS Benchmark controls in seconds. You paste the output of show running-config and the tool parses the configuration and flags anything that doesn’t meet the benchmark. This approach is faster and less error-prone than manual review for the configuration-based checks.
Automated tools cannot check some controls that require live command output (like verifying NTP synchronization status), so manual verification of those specific controls is still needed. But for configuration-based controls — which represent the majority — automation significantly reduces audit time.
Remediation Workflow
Once you have a list of failing controls, prioritize remediation by risk level: Critical and High findings first, followed by Medium. Apply changes in a maintenance window and re-audit immediately after to confirm the fix. Document before and after audit scores for compliance evidence.
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