Linux Under Siege: CISA Warns of Active D-Link Router Exploits Targeting Kernel Flaws

An emergency alert has been issued by the U.S. Cybersecurity and Infrastructure Security Agency (CISA): Critical Linux kernel flaws in D-Link routers that are nearing the end of their useful lives are being used by state-sponsored hackers to take over networks. Businesses that use Linux-based systems are at risk of widespread remote code execution (RCE) assaults, since more than 92,000 susceptible devices have been made public.

The Linux Kernel Vulnerabilities: CVE-2024-32752 & CVE-2024-32753

These flaws in D-Link's Linux firmware (DIR-859/815/825 models) enable:

• Unauthenticated RCE via HNAP

                Attackers bypass authentication to execute commands through Linux’s HNAP protocol handler.

• Permanent Root Backdoors

                Malware embeds in Linux filesystems (/etc/config), surviving reboots.

• Botnet Recruitment

               Compromised devices launch DDoS attacks from Linux environments.

Real-World Impact: A Texas HVAC supplier’s Linux-based D-Link router was weaponized to breach their industrial controls, causing $220K in ransomware damages.

Why Linux Devices Are Prime Targets

• Unpatchable Kernels = End-of-Life: D-In 2017, Link stopped providing security upgrades, exposing vulnerabilities in Linux.

• According to the FBI (2025), 61% of IoT botnets are powered by compromised Linux devices.

• Stealth Persistence: To carry out reinfection, attackers use Linux cron tasks and init scripts.

High-Risk Industries:

• Manufacturing (Linux-driven OT networks)

• Healthcare (Linux-based medical devices)

• Retail (POS systems running Linux)

Attack Chain: Taking Advantage of Linux Flaws

• Check for Linux Kernels That Are Vulnerable

               Routers running unpatched Linux versions can be found using tools like Shodan.

• Use port 8080 to send malicious HNAP payloads and take advantage of Linux kernel memory damage.

                Install Linux Malware Use ransomware such as ESXiArgs or versions of Mirai.

• Switch to Business Networks

                Use reliable routes to target Linux servers (Ubuntu, CentOS).

5 Critical Mitigations for Linux Environments

• Replace End-of-Life Linux Routers

               Immediately retire D-Link DIR-series and other unsupported Linux IoT devices.

• Hardening Linux Kernels

               Disable unused services (HNAP/UPnP); block port 8080 at firewalls.

• Segment Linux Networks

               Isolate IoT/Linux devices from core business VLANs.

• Monitor Linux Logs

                Audit /var/log/auth.log for brute-force attempts and cron anomalies.

• Reset Linux Configs

               Wipe /etc/config partitions to remove backdoors (temporary fix).

The Greater Danger: Neglected Linux Environments

A systemic crisis is revealed by this CISA alert:

• According to SANS 2025, 33% of enterprise Linux devices are running end-of-life kernels.

• Linux-based network edge devices are aggressively targeted by state actors.

• To gain first access, ransomware criminals take advantage of Linux vulnerabilities.

Bayon Technologies Group: Secure Your Linux Infrastructure

Legacy Linux devices are cyber time bombs. We provide:

✅ Linux Vulnerability Scans: Detect unpatched kernels and misconfigurations.

✅ IoT-Linux Hardening: Custom iptables policies, kernel module lockdowns.

✅ 24/7 Linux SOC Monitoring: Hunt for botnet C2 traffic and rootkits.

✅ SD-WAN Replacement: Migrate from vulnerable Linux routers to secure appliances.

Don’t let a $60 Linux router cripple your business.