Analysis by: Cris Nowell Pantanilla
 PLATFORM:

Windows

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE:

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel: Downloaded from the Internet, Dropped by other malware

This Worm arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It executes the dropped file(s). As a result, malicious routines of the dropped files are exhibited on the affected system.

  TECHNICAL DETAILS

File Size: 1,895,424 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 11 Dec 2018
Payload: Drops files, Executes files

Arrival Details

This Worm arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Installation

This Worm drops the following component file(s):

  • %Temp%\key8854321.pub
  • %Windows%\inf\averbh_noav.pnf
  • %Windows%\hdv_725x.sys -> normal file

(Note: %Temp% is the Windows temporary folder, where it usually is C:\Windows\Temp on all Windows operating system versions.. %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.)

It drops the following copies of itself into the affected system:

  • %System%\MaintenaceSrv32.exe - 32 bit system
  • %System%\MaintenaceSrv64.exe - 64 bit system

(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

Propagation

This Worm drops copies of itself in the following shared folders:

  • ADMIN$
  • C$\WINDOWS
  • D$\WINDOWS
  • E$\WINDOWS

Dropping Routine

This Worm drops the following files:

  • %System%\{wiper name} ← used to overwrite the disk
      where {wiper name} is any of the following:
    • _tdibth.exe
    • _wialx002.exe
    • acpipmi2z.exe
    • af0038bdax.exe
    • arcx6u0.exe
    • averfix2h826d_noaverir.exe
    • hidirkbdmvs2.exe
    • mdamx_5560.exe
    • mdmgcs_8.exe
    • mdmusrk1g5.exe
    • megasasop.exe
    • netbxndxlg2.exe
    • prncaz90x.exe
    • prngt6_4.exe
    • prnlx00ctl.exe
    • prnsv0_56.exe
    • tsprint_ibv.exe
    • vsmxraid.exe
    • wiacnt7001.exe
  • %System%\{network communicator name} -> Used to connect to its C&C server
    where the {network communicator name} can be any of the following:
    • netnbdrve.exe
    • prnod802.exe
    • netrndiscnt.exe
    • netrtl42l.exe
    • mdmadccnt.exe
    • prnca00.exe
    • bth2bht_ibv32.exe
    • cxfalcon_ibL32.exe
    • mdmsupr30.exe
    • digitalmediadevicectl.exe
    • mdmetech2dmv.exe
    • netb57vxx.exe
    • winwsdprint.exe
    • prnkwy005.exe
    • composite005.exe
    • mdmar1_ibv32.exe
    • prnle444.exe
    • kscaptur_ibv32.exe
    • mdmzyxlga.exe
    • usbvideob.exe
    • input_ibv48.exe
    • prnok002_ibv.exe
    • averfx2swtvZ.exe
    • wpdmtp_ibv32.exe
    • mdmti_ibv32.exe
    • printupg_ibv32.exe
    • wiabr788.exe

(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

It executes the dropped file. As a result, malicious routines of the dropped file are exhibited on the affected system.

Other Details

This Worm adds and runs the following services:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\MaintenaceSrv
Start = 2

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\MaintenaceSrv
ImagePath = "{drop copy} LocalService" or "{malware path and filename} LocalService"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\MaintenaceSrv
DisplayName = "Maintenace Host Service"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\MaintenaceSrv
DependOnService = "RpcSs"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\MaintenaceSrv
ObjectName = "LocalSystem"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\MaintenaceSrv
Description = "The Maintenace Host service is hosted in the LSA process. The service provides key process isolation to private keys and associated cryptographic operations as required by the Common Criteria. The service stores and uses long-lived keys in a secure process compl0"

It does the following:

  • It loads %Windows%\hdv_725x.sys as a kernel driver
    • Service Name: hdv_725x
    • Service Type: Kernel
    • ImagePath: \??\%Windows%\hdv_725x.sys
  • It overwrites the first sector (200 bytes) of the MBR, ultimate destroying its boot up procedure in the process.
  • There is no C&C configured for this variant, even though it has a component that is used specifically to connect to its C&C server.
  • This variant also overwrites its own files in the process.
  • It overwrites files found in the following directory:
    • C:\Users\desktop
    • C:\Users\download
    • C:\Users\document
    • C:\Users\picture
    • C:\Users\video
    • C:\Users\music
    • C:\Windows\System32\Drivers
    • C:\Windows\System32\Config\systemprofile
  • It forces the machine to shutdown, after overwriting the MBR and the files.

(Note: %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.)

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 14.682.08
FIRST VSAPI PATTERN DATE: 11 Dec 2018
VSAPI OPR PATTERN File: 14.683.00
VSAPI OPR PATTERN Date: 12 Dec 2018

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

Step 2

Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.

Step 3

Restore your system's Master Boot Record (MBR)

To restore your system's Master Boot Record (MBR):

• On Windows 2000, XP, and Server 2003:

  1. Insert your Windows Installation CD into your CD drive then restart your computer.
  2. When prompted, press any key to boot from the CD.
  3. On the Main Menu, type r to enter the Recovery Console.
    (Note for Windows 2000: After pressing r, type c to choose the Recovery Console on the repair options screen.)
  4. Type the number that corresponds to the drive and folder that contains Windows (usually C:\WINDOWS) and press Enter.
  5. Type your Administrator password and press Enter.
  6. In the input box, type the following then press Enter:
    fixmbr {affected drive}
  7. Type exit and press Enter to restart the system normally.

• On Windows Vista, 7, and Server 2008:

  1. Insert your Windows Installation DVD into the DVD drive, then press the restart button on your computer.
  2. When prompted, press any key to boot from the DVD.
  3. Depending on your Windows Installation DVD, you might be required to choose the installation language. On the Install Windows window, choose your language, locale, and keyboard layout or input method. Click Repair your computer.
  4. Select Use recovery tools that can help fix problems starting Windows. Select your installation of Windows. Click Next.
  5. If the Startup Repair window appears, click Cancel, Yes, then Finish.
  6. In the System Recovery Options menu, click Command Prompt.
  7. In the Command Prompt window, type the following then press Enter:
    BootRec.exe /fixmbr
  8. Type exit and press Enter to close the Command Prompt window.
  9. Click Restart to restart your computer normally.

• On Windows 8, 8.1, and Server 2012:

  1. Insert your Windows Installation DVD in the DVD drive, then restart your computer.
  2. When prompted, press any key to boot from the DVD.
  3. Depending on your Windows Installation DVD, you might be required to select the keyboard layout. Then on the Windows Setup window, choose your language, locale, and input method. Click Next, then click Repair your computer.
  4. Click Troubleshoot>Advanced Options>Command Prompt.
  5. In the Command Prompt window, type the following then press Enter:
    BootRec.exe /fixmbr
  6. Type exit and press Enter to close the Command Prompt window.
  7. Click Continue to restart the system normally.

Step 4

Restart in Safe Mode

[ Learn More ]

Step 5

Delete this registry key

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services
    • MaintenaceSrv

Step 6

Search and delete this file

[ Learn More ]
There may be some files that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result.
  • %Temp%\key8854321.pub
  • %Windows%\inf\averbh_noav.pnf
  • %Windows%\hdv_725x.sys

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJAN.WIN32.DISTTRACK.AA. If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check this Knowledge Base page for more information.

Step 8

Restore encrypted files from backup.


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