Trojan.ZeroaccessTrojan.ZeroAccess is a Trojan horse computer malware that affects Microsoft Windows operating systems. It is used to download other malware on an infected machine from a botnet while remaining hidden using rootkit techniques.Trojan.Zeroaccess is a Trojan horse that uses an advanced rootkit to hide itself. It can also create a hidden file system, downloads more malware, and opens a back door on the compromised computer.
The Trojan is called ZeroAccess due to a string found in the kernel driver code that is pointing to the original project folder called ZeroAccess. It is also known as max++ as it creates a new kernel device object called __max++>.
InfectionThis threat is distributed through several means. Some websites have been compromised, redirecting traffic to malicious websites that host Trojan.Zeroaccess and distribute it using the Blackhole Exploit Toolkit and the Bleeding Life Toolkit. This is the classic "drive-by download" scenario. It also updates itself through peer-to-peer networks, which makes it possible for the authors to improve it as well as potentially add new functionality.
FunctionalityThe primary motivation of this threat is to make money through pay per click advertising. It does this by downloading an application that conducts Web searches and clicks on the results. This is known as click fraud, which is a highly lucrative business for malware creators.
The threat is also capable of downloading other threats on to the compromised computer, some of which may be Misleading Applications that display bogus information about threats found on the computer and scare the user into purchasing fake antivirus software to remove the bogus threats. It is also capable of downloading updates of itself to improve and/or fix functionality of the threat. This attack is considered as vulnerable when the attack happed on a windows based server. If it's happening on a Linux base system it can be considered as a false positive.
Prevention1) User behaviour and precautions
Users can mitigate the risk of infection by being careful about clicking links found on websites, such as blogs and forums where there is potentially little control or quality checks on the content. Basic checks such as hovering with the mouse pointer over the link will normally show where the link leads to.
2) Patch operating system and software
Users are advised to ensure that their operating systems and any installed software are fully patched, and antivirus and firewall software are up to date and operational. Users are recommended to turn on automatic updates if available so that their computers can receive the latest patches and updates when they are made available.
3) Infection Method
As this threat is a Trojan, by definition it doesn't actively spread by itself. Therefore, it needs to use other methods to arrive on a compromised computer. Most commonly, Zeroaccess is spread through websites that have been compromised and redirect traffic to a malicious website that then, in turn, distribute it using the Blackhole Exploit Toolkit and the Bleeding Life Toolkit. These toolkits then attempt to exploit various vulnerabilities to penetrate the computer and infect it with Zeroaccess. It has also been observed updating itself through peer-to-peer networks. This allows the creators to continually improve the functionality of the threat as well as potentially add new functionality.
4) Functionality
The primary motivation of this threat is to make money through pay per click advertising and bitcoin mining. It does this by downloading additional software that conducts Web searches and clicks on the results or mines bitcoins. It attempts to stay hidden and undetected for as long as possible to maximize revenue generation opportunity. It does this by employing advanced rootkit techniques that hide not only the threat itself but also any other threats that Zeroaccess may download and install.
Recommendations1) Use a firewall to block all incoming connections from the Internet to services that should not be publicly available. By default, you should deny all incoming connections and only allow services you explicitly want to offer to the outside world.
2) Enforce a password policy. Complex passwords make it difficult to crack password files on compromised computers. This helps to prevent or limit damage when a computer is compromised.
3)Ensure that programs and users of the computer use the lowest level of privileges necessary to complete a task. When prompted for a root or UAC password, ensure that the program asking for administration-level access is a legitimate application.
4) Disable AutoPlay to prevent the automatic launching of executable files on network and removable drives, and disconnect the drives when not required. If write access is not required, enable read-only mode if the option is available.
5) Turn off file sharing if not needed. If file sharing is required, use ACLs and password protection to limit access. Disable anonymous access to shared folders. Grant access only to user accounts with strong passwords to folders that must be shared.
6) Turn off and remove unnecessary services. By default, many operating systems install auxiliary services that are not critical. These services are avenues of attack. If they are removed, threats have less avenues of attack.
7) If a threat exploits one or more network services, disable, or block access to, those services until a patch is applied.
8 ) Always keep your patch levels up-to-date, especially on computers that host public services and are accessible through the firewall, such as HTTP, FTP, mail, and DNS services.
9) Configure your email server to block or remove email that contains file attachments that are commonly used to spread threats, such as .vbs, .bat, .exe, .pif and .scr files.
10) Isolate compromised computers quickly to prevent threats from spreading further. Perform a forensic analysis and restore the computers using trusted media.
11) Train employees not to open attachments unless they are expecting them. Also, do not execute software that is downloaded from the Internet unless it has been scanned for viruses. Simply visiting a compromised Web site can cause infection if certain browser vulnerabilities are not patched.
12) If Bluetooth is not required for mobile devices, it should be turned off. If you require its use, ensure that the device's visibility is set to "Hidden" so that it cannot be scanned by other Bluetooth devices. If device pairing must be used, ensure that all devices are set to "Unauthorized", requiring authorization for each connection request. Do not accept applications that are unsigned or sent from unknown sources.
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