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BKDR_EXPLOSIVE.A

May 13, 2015
 Analysis by: Rommel Abraham Joven
 ALIASES:

Trojan.Explod(Symantec); Trojan:Win32/Hokobot.A.dll!dha(Microsoft); Trojan.Win32.Explosive.y(Kaspersky)

 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


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.

  TECHNICAL DETAILS

File Size:

Varies

File Type:

DLL, EXE

Memory Resident:

No

Initial Samples Received Date:

31 Mar 2015

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:

  • %Windows%\waccess{random 4 digit number}.tmp
  • %Windows%\Microsoft Help\Secure\{Username}.tc.dat
  • %Windows%\Microsoft Help\Secure\{Username}.tp.dat
  • %Windows%\Microsoft Help\Secure\vhsdata.dat
  • %Windows%\Microsoft Help\Secure\vhdata.sys

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

It creates the following folders:

  • %Windows%\Microsoft Help

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

Autostart Technique

This backdoor adds the following registry entries to enable its automatic execution at every system startup:

HKLM\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
Windows Helper = "{malware file path}"

Other System Modifications

This backdoor adds the following registry entries as part of its installation routine:

HKCU\Software\Microsoft\
Windows\ShellNoRoam\MUICache
{malware file path} = "Windows Help Service"

Backdoor Routine

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

  • Enumerate opened windows and running processes
  • Get username and computer details
  • Log keystrokes
  • Manipulation of Files
  • Propagate via removable drives
  • Provide information of drives, folders and files
  • Provide information of registry key and entries
  • Restart or end itself
  • Retrieve Internet Explorer's browsing history and saved passwords
  • Screen captures
  • Setup a remote desktop connection
  • Start or end processes
  • Uninstall itself
  • Upload files
  • Use shell commands remotely
  • View the memory

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

  • {BLOCKED}eweb.wink.ws
  • {BLOCKED}otntexplore.info

Other Details

This backdoor connects to the following URL(s) to check for an Internet connection:

  • microsoft.com

It connects to the following URL(s) to get the affected system's IP address:

  • www.whatsmyip2.somee.com

NOTES:

The DLL component contains functions used for its backdoor routine.

  SOLUTION

Minimum Scan Engine:

9.750

FIRST VSAPI PATTERN FILE:

11.572.05

FIRST VSAPI PATTERN DATE:

31 Mar 2015

VSAPI OPR PATTERN File:

11.573.00

VSAPI OPR PATTERN Date:

01 Apr 2015

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

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\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • Windows Helper = "{malware file path}"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\ShellNoRoam\MUICache
    • {malware file path} = "Windows Help Service"

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.
  • %Windows%\waccess{random 4 digit number}.tmp

Step 6

Search and delete this folder

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.  
  • %Windows%\Microsoft Help

Step 7

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

Step 8

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


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