What is ntoskrnl.exeNot all hidden components detected
by anti-rootkit (ARK) scanners and security tools are malicious
. Most ARK tools check for rookit-like behavior which is not always indicative of a malware infection. It is normal for a Firewall, anti-virus and anti-malware software, CD Emulators
, virtual machines, sandboxes
and Host based Intrusion Prevention Systems (HIPS) to exhibit rootkit-like behavior or hook into the OS kernal/SSDT (System Service Descriptor Table) in order to protect your system. SSDT is a table that stores addresses of functions that are used by Windows. Whenever a function is called, Windows looks in this table to find the address for it. Both Legitimate programs and rootkits can hook into and alter this table.
API Kernel hooks are not always bad since some system monitoring software and security tools use them as well. If no hooks
are active on a system it means that all system services are handled by ntoskrnl.exe which is a base component of Windows operating systems and the process used in the boot-up cycle of a computer. ARK scanners do not differentiate between what is good and what is bad...they only report what is found
. Therefore, even on a clean system some hidden essential components may be detected when performing a scan to check for the presence of rootkits. As such, you should not be alarmed if you see any hidden entries created by legitimate programs after performing a scan.
In most cases further investigation is required after the initial ARK scan by someone trained in rootkit detection or with advanced knowledge of the operating system. Report logs need to be analyzed and detected components identified in order to determined if they are benign, system critical or malevolent before attempted removal. Using an ARK scanner without knowing how to tell the difference between legitimate and malicious entries can be dangerous if a critical component is incorrectly removed.
* AVG Forum: How To Handle Suspicious False Positive Detection - Anti-Rootkit False Positives?
Generally when a system is infected with a malicious rootkit, there are other indications (signs of infection
) something is wrong such as very poor system performance, high CPU usage, browser redirects, BSODs, etc.