BKDR_VOLGMER.Y

November 17, 2017
 Analysis by: Rheniel Rhay Ramos
 ALIASES:

Backdoor:Win32/Joanap.I!dha (Microsoft); Trojan.Volgmer.B (Symantec); Backdoor.Volgmer (Malwarebytes)

 PLATFORM:

Windows

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Dropped by other malware, Downloaded from the Internet

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

It deletes itself after execution.

  TECHNICAL DETAILS

File Size:

131,072 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

23 Mar 2015

Payload:

Drops files

Arrival Details

This Backdoor 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 Backdoor drops the following files:

  • %User Temp%\pdm.bat -> used to delete the malware and itself
  • %System%\{Random}.dll -> detected as BKDR_VOLGMER.W

Autostart Technique

This Backdoor adds and runs the following services:

  • Service Name: "{Dropped DLL File Name}"
  • DisplayName: "{Random Combination}"
  • BinaryPathName: "%System%\svchost.exe -k LocalSystems"
  • Where {Random Combination} could be any 4 word combination of the following (i.e. "Control Intelligent User Profile Service"):
    • Application
    • Background
    • Control
    • Desktop
    • Extension
    • Function
    • Group
    • Host
    • Intelligent
    • Key
    • Layer
    • Multimedia
    • Network
    • Operation
    • Portable
    • Quality
    • Remote
    • Security
    • TCP/IP
    • User Profile
    • Volume
    • Windows
    • Device
    • Upd
    • Service
    • Management
    • Manager
    • Enum

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

Other System Modifications

This Backdoor also creates the following registry entry(ies) as part of its installation routine:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\WMI\Security
125463f3-2a9c-bdf0-d890-5a98b08d8898 = "{Hexadecimal Values}" -> encoded IP Adresses used as C&C

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\WMI\Security
f0012345-2a9c-bdf8-345d-345d67b542a1 = "{Hexadecimal Values}" -> encoded IP Adresses used as C&C

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
services\ciupsvc\Parameters
ServiceDll = "%System%\{Dropped DLL File Name}.dll"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Svchost
LocalSystems = "{Dropped DLL File Name}"

Other Details

This Backdoor deletes itself after execution.

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

13.786.07

FIRST VSAPI PATTERN DATE:

16 Nov 2017

VSAPI OPR PATTERN File:

13.787.00

VSAPI OPR PATTERN Date:

17 Nov 2017

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

Disable this malware service

[ Learn More ]
  •  
    • {Dropped DLL File Name}

Step 4

Delete this registry value

[ 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\ControlSet001\Control\WMI\Security
    • 125463f3-2a9c-bdf0-d890-5a98b08d8898 = "{Hexadecimal Values}"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\WMI\Security
    • f0012345-2a9c-bdf8-345d-345d67b542a1 = "{Hexadecimal Values}"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\services\ciupsvc\Parameters
    • ServiceDll = "%System%\{Dropped DLL File Name}.dll"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Svchost
    • LocalSystems = "{Dropped DLL File Name}"

Step 5

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.
  • %User Temp%\pdm.bat
  • %System%\{Random}.dll

Step 6

Scan your computer with your Trend Micro product to delete files detected as BKDR_VOLGMER.Y. 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.


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