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BackDoor.Farfli.122

Added to the Dr.Web virus database: 2020-02-18

Virus description added:

Packer:

absent

Compilation date:

19:36:04 26.09.2017

SHA1 hash:

  • 6a1d928709f46d344f75936519c81137258e287c (a dropper in a form of a malicious .dll module)
  • 8638bcebe84be1982c430e05e6bcd72911f36e43 (an encrypted .dat file with the payload)
  • 5c54429b219614627a925347fa5006935a70d9d7 (a decrypted .dat file with the payload)
  • 2616da1697f7c764ee7fb558887a6a3279861fac (a copy of a legitimate Symantec Network Access Control tool, RasTls.exe)

Description

A trojan library written in C++. It represents a dropper designed to deliver other malware to computers running 32-bit and 64-bit Microsoft Windows operating systems. The analyzed sample is used to load the main malicious module, hidden in the encrypted file, into the memory.

Operating routine

The library loads to the memory by the RasTls.exe tool using the DLL-hijacking mechanism. Next, it decrypts the shellcode from the RasTls.dat file stored in its body and transfers control to it:

screen BackDoor.Farfli.122 #drweb

In turn, this shellcode uses an XOR operation with the 0xCC byte to decrypt the main payload ((Dr.Web detects it as BackDoor.Farfli.125) and loads it into the memory. After that, it changes the strings MZ and PE to BB and CC, respectively, in the signature header of an executable file.

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

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