segunda-feira, 21 de julho de 2014

Rootkit a set of tool to transport malicious code

Article transcription. September 17, 2008

Malware-based rootkits fuel a multibillion dollar spyware industry by stealing individual or corporate financial information. If that weren't bad enough, rootkit-based botnets generate untold amounts of spam. Here's a look at what rootkits are and what to do about them.

Rootkits are complex and ever changing, which makes it difficult to understand exactly what you're dealing with. Even so, I'd like to take a stab at explaining them, so that you'll have a fighting chance if you're confronted with one.

Rootkits have two primary functions: remote command/control (back door) and software eavesdropping. Rootkits allow someone, legitimate or otherwise, to administratively control a computer. This means executing files, accessing logs, monitoring user activity, and even changing the computer's configuration. Therefore, in the strictest sense, even versions of VNC are rootkits. This surprises most people, as they consider rootkits to be solely malware, but in of themselves they aren't malicious at all.

One famous (or infamous, depending on your viewpoint) example of rootkit use was Sony BMG's attempt to prevent copyright violations. Sony BMG didn't tell anyone that it placed DRM software on home computers when certain CDs were played. On a scary note, the rootkit hiding technique Sony used was so good not one antivirus or anti-spyware application detected it.

Rootkits can't propagate by themselves, and that fact has precipitated a great deal of confusion. In reality, rootkits are just one component of what is called a blended threat. Blended threats typically consist of three snippets of code: a dropper, loader, and rootkit.

The dropper is the code that gets the rootkit's installation started. Activating the dropper program usually entails human intervention, such as clicking on a malicious e-mail link. Once initiated, the dropper launches the loader program and then deletes itself. Once active, the loader typically causes a buffer overflow, which loads the rootkit into memory.

Blended threat malware gets its foot in the door through social engineering, exploiting known vulnerabilities, or even brute force. Here are two examples of some current and successful exploits:

IM. One approach requires computers with IM installed (not that much of a stretch). If the appropriate blended threat gains a foothold on just one computer using IM, it takes over the IM client, sending out messages containing malicious links to everyone on the contact list. When the recipient clicks on the link (social engineering, as it's from a friend), that computer becomes infected and has a rootkit on it as well. Rich content. The newest approach is to insert the blended threat malware into rich-content files, such as PDF documents. Just opening a malicious PDF file will execute the dropper code, and it's all over.

Detection and removal depends on the sophistication of the rootkit. If the rootkit is of the user-mode variety, any one of the following rootkit removal tools will most likely work:

The problem with these tools is that you can't be sure they've removed the rootkit. Albeit more labor-intensive, using a bootable CD, such as BartPE, with an antivirus scanner will increase the chances of detecting a rootkit, simply because rootkits can't obscure their tracks when they aren't running. I'm afraid that the only way to know for sure is to have a clean computer, take a baseline, and then use an application like Encase to check for any additional code.

The author of the informations are:
Michael Kassner has been involved with wireless communications for 40-plus years, starting with amateur radio (K0PBX) and now as a network field engineer for Orange Business Services and an independent wireless consultant with MKassner Net. Current certifications include Cisco ESTQ Field Engineer, CWNA, and CWSP.
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