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Added to the Dr.Web virus database: 2011-06-07

Virus description added:

A multicomponent Trojan that blocks access to the Internet on the infected computer. The main purpose of Trojan.Mayachok.1 is web injection; that is, injecting arbitrary content into web pages opened in the browser. The following browsers are supported: Mozilla Firefox, Microsoft Internet Explorer, Opera, Google Chrome, Safari, Maxthon.

Once the Trojan is launched on the infected computer, it creates in the system32 folder a library with a name generated using the serial number of the current hard drive partition. Then the Trojan clears the browser cache and modifies the Windows system registry to register the following library:

[<HKLM>\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Windows] 'LoadAppInit_DLLs' = '00000001'
[<HKLM>\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Windows] 'AppInit_DLLs' = '<SYSTEM32>\ %name%.dll'

Next, the malware restarts the computer.

Once the computer is restarted, the dynamic library decrypts the configuration file to the allocated memory. The library performs its functions only if it is uploaded to the process that imports ws2_32.dll. If the library is uploaded to the browser process, the Trojan initiates a special stream, which monitors the status of the parent window and performs web injections if the window title changes. Moreover, Trojan.Mayachok.1 attempts to download a new configuration file from remote command and control servers.

Curing recommendations

  1. If the operating system (OS) can be loaded (either normally or in safe mode), download Dr.Web Security Space and run a full scan of your computer and removable media you use. More about Dr.Web Security Space.
  2. If you cannot boot the OS, change the BIOS settings to boot your system from a CD or USB drive. Download the image of the emergency system repair disk Dr.Web® LiveDisk , mount it on a USB drive or burn it to a CD/DVD. After booting up with this media, run a full scan and cure all the detected threats.
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Use Dr.Web Anti-virus for macOS to run a full scan of your Mac.

After booting up, run a full scan of all disk partitions with Dr.Web Anti-virus for Linux.

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  1. If the mobile device is operating normally, download and install Dr.Web for Android. Run a full system scan and follow recommendations to neutralize the detected threats.
  2. If the mobile device has been locked by Android.Locker ransomware (the message on the screen tells you that you have broken some law or demands a set ransom amount; or you will see some other announcement that prevents you from using the handheld normally), do the following:
    • Load your smartphone or tablet in the safe mode (depending on the operating system version and specifications of the particular mobile device involved, this procedure can be performed in various ways; seek clarification from the user guide that was shipped with the device, or contact its manufacturer);
    • Once you have activated safe mode, install the Dr.Web for Android onto the infected handheld and run a full scan of the system; follow the steps recommended for neutralizing the threats that have been detected;
    • Switch off your device and turn it on as normal.

Find out more about Dr.Web for Android