Rootkits are typical type of  malware, which has not get lots of exposure, but are deadly in their effect and can cause a lot of damage to your PC Security. Without going into details let me quote Wikipedia to explain what exactly is a rootkit.

rootkit is software that enables continued privileged access to a computer while actively hiding its presence from administrators by subverting standard operating system functionality or other applications. The term rootkit is a concatenation of “root” (the traditional name of the privileged account on Unix operating systems) and the word “kit” (which refers to the software components that implement the tool). The term “rootkit” has negative connotations through its association with malware.[1]

Typically, an attacker installs a rootkit on a computer after first obtaining root-level access, either by exploiting a known vulnerability or by obtaining a password (either by cracking the encryption, or through social engineering). Once a rootkit is installed, it allows an attacker to mask the ongoing intrusion and maintain privileged access to the computer by circumventing normal authentication and authorization mechanisms. Although rootkits can serve a variety of ends, they have gained notoriety primarily as malware, hiding applications that appropriate computing resources or steal passwords without the knowledge of administrators and users of affected systems. Rootkits can target firmware, a hypervisor, the kernel, or—most commonly—user-mode applications.

Rootkit detection is difficult because a rootkit may be able to subvert the software that is intended to find it. Detection methods include using an alternate, trusted operating system; behavioral-based methods; signature scanning; difference scanning; and memory dump analysis. Removal can be complicated or impossible, especially if the rootkit resides in the kernel; reinstallation of the operating system may be the only alternative.

Freeware Rootkit Detection Tool from NoVirusThanks

detect rootkit

NoVirusThanks™ is a project started in June 2008 whos primary objective to create software and services related to computer and Internet security. They offer various services and software for the security conscious in order to help users fight Internet threats.

NoVirusThanks Anti-Rootkit is a sophisticated low-level system analysis tool whose main goal is to detect the presence of malware and rootkits. Hidden processes, hidden drivers, stealth DLL modules, code hooks etc. are just a few of the objects which can be detected in user space and system memory.

A few days back, they have released the free version of their popular Anti Rootkit Tool for the personal use. There are a few limitations of this freeware version as compared to the paid version, but most people may not need them for personal use.

And if you want to know, the paid version costs only $20.

Please be advised the rootkit detection is not something meant for an average computer user. If you are comfortable with the security jargons and know the security issues well, then you can go ahead.

Here is a video, which explains some of the features.

[Download NoVirusThanks Anti Rootkit Tool]