BKDR_TAPAZOM.ENM

 Analysis by: Michael Jay Villanueva

 ALIASES:

Backdoor:Win32/Tapazom.A (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:

Downloaded from the Internet, Dropped by other malware

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 does not have any propagation routine.

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

  TECHNICAL DETAILS

File Size:

29,184 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

15 Sep 2016

Payload:

Connects to URLs/IPs, 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.

Installation

This backdoor drops the following copies of itself into the affected system and executes them:

  • %Application Data%\{GUID}\GenuineIntel-core.exe

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

It creates the following folders:

  • %Application Data%\{GUID}

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

It adds the following mutexes to ensure that only one of its copies runs at any one time:

  • decomcs64.dll

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
GenuineIntel² = %Application Data%\{GUID}\GenuineIntel-core.exe

Propagation

This backdoor does not have any propagation routine.

Backdoor Routine

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

  • Screen Capture
  • List and Control Webcams
  • Log keystrokes
  • Execute, rename, copy, and delete files/folders
  • Upload/Send files
  • Steal system information (Driver, Audio, other machine information)
  • Display message (Message box)
  • Connect to a specific URL
  • Terminate applications
  • Shutdown, Restart, Hibernate, or Log-off Machine
  • Monitor Mouse Activities

Other Details

This backdoor does the following:

  • It connects to the following command-and-control (C&C) server to download a file:
    • {BLOCKED}zo.{BLOCKED}to.org:1431
  • It sends the following request format:
    • GETSERVER|111|46

    However, as of this writing, there was no response from the server

  • It saves the downloaded file as follows:
    • {malware path}\decomcs64.dll -> Trend Micro detect this as BKDR_TAPAZOM.XORENC
  • It then executes the downloaded DLL by loading it in the memory of the malware process.

NOTES:

This backdoor does not have rootkit capabilities.

It does not exploit any vulnerability.

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

12.778.04

FIRST VSAPI PATTERN DATE:

15 Sep 2016

VSAPI OPR PATTERN File:

12.779.00

VSAPI OPR PATTERN Date:

16 Sep 2016

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 BKDR_TAPAZOM.ENM

[ 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
    • GenuineIntel² = %Application Data%\{Random GUID}\GenuineIntel-core.exe

Step 5

Remove malware/grayware files dropped/downloaded by BKDR_TAPAZOM.ENM. (Note: Please skip this step if the threats listed below have already been removed.)

    • BKDR_TAPAZOM.XORENC

Step 6

Search and delete these folders

[ 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.
  • %Application Data%\{GUID}

Step 7

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