TROJ_DESBACK.A

February 14, 2018
 Analysis by: Rheniel Rhay Ramos
 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Dropped by other malware

This Trojan may be dropped by other malware.

It modifies registry entries to disable various system services. This action prevents most of the system functions to be used.

It does not have any propagation routine.

It does not have any backdoor routine.

  TECHNICAL DETAILS

File Size:

36,864 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

09 Feb 2018

Payload:

Modifies system registry

Arrival Details

This Trojan may be dropped by the following malware:

Installation

This Trojan adds the following processes:

  • vssadmin.exe delete shadows /all /quiet
  • wbadmin.exe delete catalog -quiet
  • bcdedit.exe /set {default} bootstatuspolicy ignoreallfailures
  • bcdedit /set {default} recoveryenabled no
  • wevtutil.exe cl System
  • wevtutil.exe cl Security

Other System Modifications

This Trojan modifies registry entries to disable the following system services:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{Service Name} -> (All Services)
Start = "4"

Propagation

This Trojan does not have any propagation routine.

Backdoor Routine

This Trojan does not have any backdoor routine.

Other Details

This Trojan does the following:

  • It wipes all writeable files in the shared folders by changing the contents to "0x00" or uninitialized data.
  • It does nothing for one hour then it shutdowns the system.

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

13.964.04

FIRST VSAPI PATTERN DATE:

09 Feb 2018

VSAPI OPR PATTERN File:

13.965.00

VSAPI OPR PATTERN Date:

10 Feb 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

Identify and terminate files detected as TROJ_DESBACK.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

Scan your computer with your Trend Micro product to delete files detected as TROJ_DESBACK.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:

NOTES:

    Clean solution:
  1. Enable services disabled using the command prompt.
  2. Run cmd.exe as administrator.
  3. To enable Volume Shadow Service use the following command: net start vss
  4. To enable Windows Error Recovery Screen on Startup use the following command: bcdedit /set {default} bootstatuspolicy displayallfailures
  5. To enable Startup Repair use the following command: /bcedit /set {default} recoveryenabled Yes


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