1. Symantec/
  2. Security Response/
  3. Ransom.BadRabbit

Ransom.BadRabbit

Risk Level 2: Low

Discovered:
October 24, 2017
Updated:
October 26, 2017 3:30:10 AM
Type:
Trojan, Worm
Infection Length:
Varies
Systems Affected:
Windows
The Trojan spreads within a local network via SMB shares. One of the initial infection vectors is a bogus Adobe Flash Player update on compromised websites.

When the Trojan is executed, it creates the following files:
  • %SystemDrive%\README.txt
  • %Windir%\dispci.exe
  • %Windir%\cscc.dat
  • %Windir%\infpub.dat
  • %Windir%\[HEXADECIMAL VALUE].tmp
  • %Windir%\Tasks\drogon.job
  • %Windir%\Tasks\rhaegal.job

The Trojan then deletes the following files:
  • %Windir%\infpub.dat
  • %Windir%\[HEXADECIMAL VALUE].tmp

Next, the Trojan creates the following registry entries:
  • HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\cscc\"DisplayName" = "Windir Client Side Caching DDriver"
  • HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\cscc\"ImagePath" = "cscc.dat"
  • HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\cscc\"Type" = "1"
  • HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\cscc\"ErrorControl" = "3"
  • HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\cscc\"Start" = "0"
  • HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\cscc\"DependOnGroup" = ""
  • HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\cscc\"Group" = "Filter"
  • HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\cscc\"DependOnService" = "FltMgr"
  • HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\{4D36E965-E325-11CE-BFC1-08002BE10318}\"UpperFilters" = "cscc"
  • HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\{71A27CDD-812A-11D0-BEC7-08002BE2092F}\"LowerFilters" = "cscc"

The Trojan then encrypts files with the following extensions:
  • .3ds
  • .7z
  • .accdb
  • .ai
  • .asm
  • .asp
  • .aspx
  • .avhd
  • .back
  • .bak
  • .bmp
  • .brw
  • .c
  • .cab
  • .cc
  • .cer
  • .cfg
  • .conf
  • .cpp
  • .crt
  • .cs
  • .ctl
  • .cxx
  • .dbf
  • .der
  • .dib
  • .disk
  • .djvu
  • .doc
  • .docx
  • .dwg
  • .eml
  • .fdb
  • .gz
  • .h
  • .hdd
  • .hpp
  • .hxx
  • .iso
  • .java
  • .jfif
  • .jpe
  • .jpeg
  • .jpg
  • .js
  • .kdbx
  • .key
  • .mail
  • .mdb
  • .msg
  • .nrg
  • .odc
  • .odf
  • .odg
  • .odi
  • .odm
  • .odp
  • .ods
  • .odt
  • .ora
  • .ost
  • .ova
  • .ovf
  • .p12
  • .p7b
  • .p7c
  • .pdf
  • .pem
  • .pfx
  • .php
  • .pmf
  • .png
  • .ppt
  • .pptx
  • .ps1
  • .pst
  • .pvi
  • .py
  • .pyc
  • .pyw
  • .qcow
  • .qcow2
  • .rar
  • .rb
  • .rtf
  • .scm
  • .sln
  • .sql
  • .tar
  • .tib
  • .tif
  • .tiff
  • .vb
  • .vbox
  • .vbs
  • .vcb
  • .vdi
  • .vfd
  • .vhd
  • .vhdx
  • .vmc
  • .vmdk
  • .vmsd
  • .vmtm
  • .vmx
  • .vsdx
  • .vsv
  • .work
  • .xls
  • .xlsx
  • .xml
  • .xvd
  • .zip

Next, the Trojan creates the following scheduled tasks to carry out certain functionality:
  • schtasks /Create /RU SYSTEM /SC ONSTART /TN rhaegal /TR "%SYSTEM%\cmd.exe /C Start \"\" \"%Windir%\dispci.exe\" -id [NUMBER] && exit"
  • schtasks /Create /SC once /TN drogon /RU SYSTEM /TR "%SYSTEM%\shutdown.exe /r /t 0 /f" /ST [TIME]

After encryption, the Trojan clears the following logs using wevtutil:
  • Setup
  • System
  • Security
  • Application

The Trojan then deletes the USN journal using fsutil.

The Trojan tries to spread itself using SMB with a hardcoded list of credentials or from Hacktool.Mimikatz.

Next, the Trojan overwrites the first sectors of the disk and forces a reboot.

After the compromised computer has rebooted, the Trojan displays a ransom note informing the user their files have been encrypted and providing instructions on how they may pay to have the files decrypted.

Recommendations

Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":

  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • If a threat exploits one or more network services, disable, or block access to, those services until a patch is applied.
  • 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.
  • 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.
  • Isolate compromised computers quickly to prevent threats from spreading further. Perform a forensic analysis and restore the computers using trusted media.
  • 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.
  • 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.
  • For further information on the terms used in this document, please refer to the Security Response glossary.
Writeup By: Benjamin Moench
Summary| Technical Details| Removal

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2016 Internet Security Threat Report, Volume 21
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