DexCrypt MBRLocker Demands 30 Yuan To Gain Access to Computer

silversurfer · Feb 10, 2018

Code:
A new Chinese MBRLocker called DexLocker has been discovered that asks for 30 Yuan to get access to a computer. First discovered by security researcher JAMESWT, this ransomware will modify the master boot record of the victim's computer so that it shows a ransom note before Windows starts.

Unfortunately, I was not able to get this sample to run, so I have no first hand analysis of this ransomware. The AnyRun video posted by JAMESWT, though, shows that once you install the ransomware, it immediately reboots the computer and the victim is greeted with an ascii skull and a message to send 30 yaun to the 2055965068 qq address in order to get access to their computer again.

DexCrypt Lock Screen
Microsoft's Windows Defender Security Team saw Jame's tweet and tweeted that they have labeled the MBRLocker as RansomDOS/Dexcrypt.A and that it can be detected by Windows Defender.

ICYMI: New #ransomware writes code to the Master Boot Record (MBR) and immediately restarts computer to show a note that asks for 30 yuan as ransom. Windows Defender AV detects and blocks this ransomware as Ransom:Win32/Dexcrypt and its MBR-writing code as RansomDOS/Dexcrypt.A. JAMESWT on Twitter

— Windows Defender Security Intelligence (@WDSecurity) February 9, 2018

According to kangxiaopao, you can enter the ssssss password to gain access. If this password does not work and it does only replace the MBR, it can be fixed by booting up into the Windows Recovery Console and restoring the Master Boot Record using the following commands:

Code:

bootrec /RebuildBcd bootrec /fixMbr bootrec /fixboot

Once you enter these commands, you can reboot and get access again to Windows again.

IOCs
Hashes:
dfc56a704b5e031f3b0d2d0ea1d06f9157758ad950483b44ac4b77d33293cb38