How rootkit works
A rootkit modifies the operating system or firmware so that processes, files, network connections and registry entries belonging to the attacker are hidden from normal tools. Kernel-mode rootkits load drivers; bootkits infect the boot process; firmware rootkits persist even after a reinstall.
Attackers install rootkits after gaining administrator access, using them to keep long-term control, steal data, hide other malware, or launch further attacks. Because the system reports what the rootkit allows it to see, normal scans may show nothing wrong. Memory dumps taken early preserve evidence that disappears after a reboot.
Why it matters for Canadian organizations
Rootkits indicate a deep compromise, usually with long dwell time. Any personal information on an affected system must be treated as potentially exposed, which can trigger assessment and reporting duties under PIPEDA and Law 25.
Detection often depends on looking from outside the infected system, using memory forensics, integrity checks and behavioural monitoring. Organizations that rely only on signature-based tools can miss them for months. Prompt containment and expert forensic help are essential when a rootkit is suspected, because evidence can vanish on reboot. Because rootkits imply deep access, assume attacker credentials on that system are compromised.
How to defend against it
Prevent installation by patching, restricting administrator rights, enabling secure boot, using driver signing enforcement and keeping firmware updated. Deploy endpoint detection and response with behavioural and kernel-level visibility.
If a rootkit is suspected, isolate the machine, capture memory and disk images for forensics, and rebuild from trusted media rather than attempting cleanup. Rotate any credentials used on the system. Plan ahead: keep trusted installation media and known-good configuration baselines available so rebuilds are quick and reliable when needed. Report relevant incidents through proper channels and preserve evidence for any legal or insurance steps.
Frequently asked questions
How do you detect a rootkit?
Use tools that inspect from outside the compromised operating system, such as offline scanning, memory forensics and integrity checks, along with EDR behavioural detection. Network anomalies can also give it away. Using a trusted, separate environment gives more reliable results.
Can a rootkit be removed?
Sometimes, but cleaning is unreliable because the rootkit can hide remnants. The safest response is to rebuild the system from trusted media and restore only verified data. Never trust cleanup tools run from the compromised system itself.
Is a rootkit a virus?
Not exactly. A rootkit is a concealment toolkit that hides malicious activity and maintains privileged access. It may be delivered alongside viruses, trojans or other malware. Rootkits may accompany other malware families rather than replace them.
Related service: Cyber defense