Analysis by: Joselyn Canuela
 PLATFORM:

Windows

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel: Spammed via email

This Backdoor arrives as an attachment to email messages spammed by other malware/grayware or malicious users.

It executes commands from a remote malicious user, effectively compromising the affected system.

  TECHNICAL DETAILS

File Size: 1,978,880 bytes
File Type: DOC
Memory Resident: Yes
Initial Samples Received Date: 31 Aug 2017
Payload: Connects to URLs/IPs, Executes commands

Arrival Details

This Backdoor arrives as an attachment to email messages spammed by other malware/grayware or malicious users.

Installation

This Backdoor adds the following processes:

  • rundll32.exe

It injects codes into the following process(es):

  • created rundll32.exe

Other System Modifications

This Backdoor adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Office\{Application Version}\Word\
Security
AccessVBOM = "1"

Backdoor Routine

This Backdoor executes the following commands from a remote malicious user:

  • Process Spawning
  • Execute Commands using cmd
  • Execute Commands using powershell
  • Open/Move/Copy/Upload a File
  • Create/Connect to a Pipe
  • Create/Terminate a Process
  • Collect File Information
  • Collect Process Information
  • Use/Destroy Kerberos Ticket
  • Impersonate User
  • Create/Remove Directory
  • Get Available Drives
  • Start/Query/Delete a Service

It connects to the following URL(s) to send and receive commands from a remote malicious user:

  • {BLOCKED}.{BLOCKED}.58.231

Other Details

This Backdoor does the following:

  • It performs its intended routine if the UserDNSDomain has "bs.co".

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 13.630.04
FIRST VSAPI PATTERN DATE: 31 Aug 2017
VSAPI OPR PATTERN File: 13.631.00
VSAPI OPR PATTERN Date: 01 Sep 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

Terminate a malware/grayware process

[ Learn More ]

*Note: If the detected process is not displayed in theWindows Task Manager, continue doing the next steps.

    • created rundll32.exe

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_CURRENT_USER\Software\Microsoft\Office\{Application Version}\Word\Security
    • AccessVBOM = "1"

Step 5

Scan your computer with your Trend Micro product to delete files detected as W2KM_CONBEAJECT.A. 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.


Did this description help? Tell us how we did.