CEIDPageLock Rootkit Hijacks Web Browsers

A new rootkit that has been distributed via the RIG exploit kit over the past few weeks can manipulate web browsers and also contains sophisticated defense mechanisms, Check Point says.

Dubbed CEIDPageLock, the malware was initially discovered a few months ago, when it was attempting to modify the homepage of a victim’s browser. The rootkit is currently attempting to turn the victim browser’s homepage into a site pretending to be a Chinese web directory.

On top of these sophisticated features, the latest versions of the malware monitors user browsing and, when the user attempts to access several popular Chinese websites, it dynamically replaces the content of those sites with the fake home page.

“Browser hijacking employed by malware like CEIDPageLock, can be profitable due to revenue earned via redirecting victims to search engines that share ad revenue with the referrers,” Check Point explained.

The malware’s operators also use a series of hijacking tricks to gather data on the victims’ browsing habits, such as the monitoring of visited sites, which could be used for its own ad campaigns or sold to other companies.

A dropper is used during infection, to extract a digitally signed 32-bit kernel-mode driver. The certificate was issued by Thawte but has been already revoked. After registering and starting the driver, the dropper sends the infected machine’s MAC address and user-id.

The driver is launched during startup and remains fairly stealthy, being able to evade antivirus solutions. It was designed to connect to one of two command and control (C&C) domains hardcoded in it and to download a homepage configuration to tamper the browser with.

The newer version of the malware is also packed with VMProtect, thus making analysis and unpacking difficult, especially since it is also a kernel mode driver, Check Point notes.

The iteration also includes a “redirection” capability, to send victims to the fake homepage whenever they attempt to access targeted sites. The rootkit also checks every outgoing HTTP message for specific strings and adds the process to the redirected list when a string is encountered.

The malware also blocks browsers from accessing a series of anti-virus’ files and includes the ability to create registry key in a security product.

The vast majority of CEIDPageLock’s targets are located in China, with only a negligible number of infections outside the country, Check Point says.

“At first glance, writing a rootkit that functions as a browser hijacker and employing sophisticated protections such as VMProtect, might seem like overkill. However, it seems that this simple malicious technique can be very profitable and thus the attackers believe that it is worthwhile to invest in building a stealthy and persistent tool for it,” the security firm notes.

Furthermore, the malware has the ability to execute code on an infected device. Coupled with the fact that it operates from the kernel and its persistence mechanism, CEIDPageLock is “a potentially perfect backdoor,” Check Point concludes.

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