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Linux systems are not inherently under attack at some uniquely high rate; the evidence does not establish a Linux-specific epidemic or a reliable comparison with other operating systems. Like any internet-connected computer, a Linux host can become vulnerable when software is out of date, unnecessary services are reachable, or administrative access and privileges are poorly controlled. The practical response is to patch supported software, reduce exposure, protect accounts, prepare recoverable backups, and check configurations against a baseline suited to your distribution and release.
Why Linux systems can be exposed
Attackers have more opportunity when a host exposes services that do not need to be public, runs software with known unpatched vulnerabilities, or allows administrative access without adequate controls. Accounts with more privilege than their users or services require can make the consequences of a compromise worse.
CISA and NSA wrote in their 2023 advisory, “Poor patch management and network hygiene practices often enable adversaries to discover open attack vectors and exploit critical vulnerabilities.” That is a general warning about security practice, not evidence that Linux is uniquely targeted.
A CISA/NSA advisory also describes a specific case involving Cisco IOS XR, a Linux-based network operating system: actors enabled an additional SSH endpoint, created a local user, and granted that account sudo privileges. This illustrates why remote administration and privileged accounts matter; it does not mean that ordinary Linux computers share the appliance’s configuration or exposure. See the advisory’s account of the device-specific incident.
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Patch supported systems and applications
Keep the operating system on a supported release and install updates for its packages and applications. Check your distribution’s security notices for fixes that apply to your release, and follow its guidance on update timing and any required restart. Commands, package lifecycles, and reboot requirements differ across distributions, so there is no single safe update command for every Linux system.
For servers, include applications and services you installed separately from the base system in your patching process. A current operating system does not automatically mean every application on it is current.
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Reduce the services reachable over the network
- Inventory listeners. Identify which services accept network connections and which interfaces they use. Consult your distribution’s documentation for release-appropriate inspection tools.
- Remove exposure you do not need. Disable or uninstall unnecessary services rather than leaving them reachable by default.
- Restrict necessary services. Use firewall and access controls to limit management and application services to intended clients or trusted networks where practical.
- Monitor what remains exposed. Keep required internet-facing infrastructure under review and apply fixes promptly.
CISA and NSA recommend minimizing unnecessary internet exposure and monitoring infrastructure that must remain exposed. The right firewall rules and service settings depend on the distribution, network, and role of the machine; do not copy configuration commands intended for a different system without checking its documentation.
Protect SSH and administrative accounts
- Allow SSH and other management services to be reached only by the users and networks that need them.
- For administrative roles, prefer public-key authentication when it is operationally feasible.
- Before disabling password authentication, test another working access path and confirm you have a recovery method. Otherwise, a configuration change can lock out legitimate administrators.
- Remove or disable accounts that are no longer needed, avoid using root for routine work, and grant sudo or other elevated privileges only when required.
CISA and NSA’s example of an unauthorized account gaining sudo privileges on Cisco IOS XR shows the potential impact of account and privilege control failures. Its extra SSH endpoint and device-specific details should not be treated as default conditions on other Linux systems.
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Limit privileges and prepare backups
Apply least privilege to both people and services: give each account and process only the permissions it needs. Maintain backups of critical data that are protected from routine access by the systems they protect. An offline copy can help preserve a recovery option if an attacker or destructive incident affects the live environment. CISA’s ransomware guidance supports offline backups, asset inventory, and least privilege; it does not prescribe a particular backup product or medium.
For a home or small-office setup, a detachable external drive is one possible way to keep a copy offline when it is disconnected and stored safely. Larger environments may need a different arrangement suited to their recovery requirements. Identify critical assets and decide what must be restored first; a backup is useful only if the needed data can be recovered.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Choose a security baseline that fits the system
A benchmark is a set of recommended configuration checks, not a universal configuration that should be applied unchanged to every Linux host. Choose one that matches the distribution, release, and machine role. A workstation, general-purpose server, and system subject to a compliance requirement may have different needs.
NIST’s Linux hardening guidance names Security Content Automation Protocol (SCAP) Compliance Checker (SCC) and OpenSCAP for checking against an applicable DISA Security Technical Implementation Guide (STIG) or CIS Benchmark. Red Hat’s RHEL 8 Security hardening guide documents hardening and compliance profiles for that product and release. Its profile details are not general Linux defaults.
| Option | Coverage and fit | Assessment or remediation | Operational considerations |
|---|---|---|---|
| SCC or OpenSCAP | NIST names these for Linux compliance checks against an applicable DISA STIG or CIS Benchmark; select content suitable for the distribution and release. | They can be used to check a system against selected policy; NIST also describes OpenSCAP for policy remediation. | Confirm the content matches the host and review proposed changes before remediation. |
| Red Hat RHEL 8 security profiles | Specific to Red Hat Enterprise Linux 8 and its documented compliance profiles. | The guide covers hardening and compliance material; behavior depends on the selected profile and method. | Not a general-purpose baseline for other distributions or releases; validate compatibility with the system’s role. |
Automated remediation can change system behavior or disrupt services. Review the profile, understand the effects, and test changes in a suitable environment before applying them to production. NIST’s Linux hardening documentation describes SCC and OpenSCAP alongside the use of applicable benchmarks.
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