BKDR_MIRAI.B

May 25, 2017
 Analysis by: Johnlery Triunfante
 ALIASES:

Trojan-Downloader.Win32.Agent.silgjq (KASPERSKY); Backdoor:Win32/Mirai (MICROSOFT)

 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:

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

As of this writing, the said sites are inaccessible.

  TECHNICAL DETAILS

File Size:

50,376 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

06 Feb 2017

Payload:

Compromises system security, Downloads 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.

Backdoor Routine

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

  • Display console window
  • Start service
  • Stop service
  • Delete service
  • Create service
  • Run malware as application
  • Run malware as service

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

  • http://up.{BLOCKED}s.pw:8888/

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

Download Routine

This Backdoor accesses the following websites to download files:

  • http://up.{BLOCKED}s.pw:8888/ver.txt - the malware checks this file to determine if it needs to update itself
  • http://up.{BLOCKED}s.pw:8888/update.txt

It saves the files it downloads using the following names:

  • %System Root%\windows\system\upslist.txt

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

As of this writing, the said sites are inaccessible.

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

13.236.05

FIRST VSAPI PATTERN DATE:

22 Feb 2017

VSAPI OPR PATTERN File:

13.237.00

VSAPI OPR PATTERN Date:

23 Feb 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

Restart in Safe Mode

[ Learn More ]

Step 4

Identify and terminate files detected as BKDR_MIRAI.B

[ 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 5

Search and delete these files

[ 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.  
  • %System Root%\windows\system\upslist.txt

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_MIRAI.B. 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 7

Scan your computer with your Trend Micro product to delete files detected as BKDR_MIRAI.B. 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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