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Backdoor.Win32.SLUB.A

March 07, 2019
 Analysis by: Warren Adam Sto. Tomas
 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:

Downloaded from the Internet, Dropped by other malware


This backdoor uses several known websites to receive backdoor commands, facilitate communication of the commands, and upload files.

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 may be downloaded by other malware/grayware from remote sites.

It executes commands from a remote malicious user, effectively compromising the affected system. However, as of this writing, the said sites are inaccessible.

It gathers certain information on the affected computer.

  TECHNICAL DETAILS

File Size:

856576 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

25 Feb 2019

Payload:

Connects to URLs/IPs, Steals information

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.

It may be downloaded by the following malware/grayware from remote sites:

Autostart Technique

This Backdoor creates the following registry entries to enable automatic execution of dropped component at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
Microsoft Setup Initializazion = rundll32 "%All Users Profile%\update\Windows-RT-KB2937636.dll",UpdateMPUnits

Backdoor Routine

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

  • Execute a command
  • Download and execute a file
  • Update itself
  • Destroy itself
  • Capture screen
  • List, copy, download, or upload file
  • Create or delete directory
  • List or kill process
  • Get information from drive
  • Query, read, or write registry
  • Change timeout

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

  • https://gist.{BLOCKED}b.com/{BLOCKED}522/626a3a68a2cc2a91c1ece1eed7610c8a

However, as of this writing, the said sites are inaccessible.

Information Theft

This Backdoor gathers the following information on the affected computer:

  • Computer name
  • User name
  • Drives information
  • Running processes

Other Details

This Backdoor does the following:

  • It uses the following websites to send information from the affected system:
    • https://slack.com/api/files.upload -> captured screen
    • https://slack.com/api/chat.postMessage -> other backdoor commands
    • https://file.io -> website where file is uploaded

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

14.842.07

FIRST VSAPI PATTERN DATE:

25 Feb 2019

VSAPI OPR PATTERN File:

14.843.00

VSAPI OPR PATTERN Date:

26 Feb 2019

Step 1

Before doing any scans, Windows 7, Windows 8, Windows 8.1, and Windows 10 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

Identify and terminate files detected as Backdoor.Win32.SLUB.A

[ Learn More ]
  1. Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

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\Windows\CurrentVersion\Run
    • Microsoft Setup Initializazion = rundll32 "%All Users Profile%\update\Windows-RT-KB2937636.dll",UpdateMPUnits

Step 5

Scan your computer with your Trend Micro product to delete files detected as Backdoor.Win32.SLUB.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 the following Trend Micro Support pages for more information:


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