BKDR_NUKESPED.E

 Analysis by: Rheniel Rhay Ramos

 ALIASES:

Backdoor.Win32.Agent.gsci (Kaspersky), Backdoor:Win64/Escad.F!dha (Microsoft), Backdoor.Darpapox (Symantec)

 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:

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 executes then deletes itself afterward.

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

  TECHNICAL DETAILS

File Size:

512,996 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

23 May 2017

Payload:

Drops files, Deletes 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 files:

  • %User Temp%\Microsoft.Win32.TaskScheduler.dll -> component for SetTaskPathDl
  • %User Temp%\drmanidd32.dll ->also detected as BKDR_NUKESPED.E
  • %Application Data%\Adobe\Update\SecuUpdates.dll -> renamed copy of drmanidd32.dll

(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp 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.. %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 drops and executes the following files:

  • %User Temp%\end.bat -> used to delete itself and the malware
  • %User Temp%\start.bat -> used to execute and delete components
  • %User Temp%\SetTaskPathDl.exe ->used to rename and create a scheduled task for drmanidd32.dll

(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp 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 executes then deletes itself afterward.

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

  • 74tw9401-719s-85hk-op16-562ge02bm369

Other System Modifications

This Backdoor deletes the following files:

  • %User Temp%\end.bat
  • %User Temp%\start.bat
  • %User Temp%\SetTaskPathDl.exe
  • %User Temp%\Microsoft.Win32.TaskScheduler.dll
  • %User Temp%\drmanidd32.dll

(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp 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.)

Backdoor Routine

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

  • go -> Ok signal for the backdoor capability
  • ti -> Change Sleep time multiplier
  • sh -> Has same template as fs and ts but has not implemented any function after resolving the host address
  • fs -> Send and Receive Backdoor Commands via UDT Library (UDT::socket, UDT::connect, etc)
    Has the following subcommands:
    • _dir Send a directory listing for path specified
    • _exe Execute arbitrary shell commands via WinExec
    • _get Encrypt and upload arbitrary file
    • _got Encrypt and upload arbitrary file then delete file
    • _put Download, Decrypt and save arbitrary file
    • _quit Exit “fs” backdoor command loop
  • ts -> Send and Receive Backdoor Commands via common APIs (socket, bind, connect, etc)
    Has the following subcommands:
    • _dir Send a directory listing for path specified
    • _del Delete arbitray file
    • _exe Execute arbitrary shell commands via WinExec
    • _get Encrypt and upload arbitrary file
    • _got Encrypt and upload arbitrary file then delete file
    • _put Download, Decrypt and save arbitrary file
    • _dll Inject a DLL into a process via remote thread
    • _dlu Unload DLL
    • _cap Save screenshot to file and send to C&C, then delete
    • _inf Gather info to a temp file and Send to C&C, then delete:
      • Operating system version
      • Username
      • Computer name
      • System drive
      • Local time
      • All connected drives and properties
      • Network adapter properties
      • Disk free space
      • All installed programs
    • _cmd Execute comspec with arbitrary parameter and send results to C&C
    • _prc Send a full running process list to C&C
    • _quit Exit backdoor command thread
  • dl -> DLL Injection via CreateRemoteThread
  • du -> DLL Unloading via FreeLibrary
  • de -> Secure Delete File Function, renames multiple times then delete
  • cm -> Execute ComSpec with Arbitrary Parameters
  • cu -> Send sytem info through the DNS query
  • ex -> Execute Arbitrary Shell Commands

Other Details

This Backdoor does the following:

  • Tries to resolve a specific C2 DNS name by querying a CNAME on the following URLs:
    • {BLOCKED}.{BLOCKED}ttp.com
    • {BLOCKED}.{BLOCKED}.tm
    • {BLOCKED}o.{BLOCKED}.net

    However, the CNAME “pYjr6YpmK-lKJ2YLB0csBgYGqMbnxmfmSeaG.e.r“, was not resolved during the analysis.

It adds the following scheduled tasks:

    • Task Name: Adobe Update Checker
    • Schedule: At log on of User
    • Task to be Run: rundll32.exe %appdata%\Adobe\Update\SecuUpdates.dll,start now

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

14.220.06

FIRST VSAPI PATTERN DATE:

29 Apr 2018

VSAPI OPR PATTERN File:

14.221.00

VSAPI OPR PATTERN Date:

30 Apr 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 BKDR_NUKESPED.E

[ 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

Deleting Scheduled Tasks

The following {Task Name} - {Task to be run} listed should be used in the steps identified below:  

  • Adobe Update Checker - rundll32.exe %appdata%\\Adobe\\Update\\SecuUpdates.dll,start now

For Windows 2000, Windows XP, and Windows Server 2003:

  1. Open the Windows Scheduled Tasks. Click Start>Programs>Accessories>
    System Tools>Scheduled Tasks.
  2. Locate each {Task Name} values listed above in the Name column.
  3. Right-click on the said file(s) with the aforementioned value.
  4. Click on Properties. In the Run field, check for the listed {Task to be run}.
  5. If the strings match the list above, delete the task.

For Windows Vista, Windows 7, Windows Server 2008, Windows 8, Windows 8.1, and Windows Server 2012:

  1. Open the Windows Task Scheduler. To do this:
    • On Windows Vista, Windows 7, and Windows Server 2008, click Start, type taskschd.msc in the Search input field, then press Enter.
    • On Windows 8, Windows 8.1, and Windows Server 2012, right-click on the lower left corner of the screen, click Run, type taskschd.msc, then press Enter.
  2. In the left panel, click Task Scheduler Library.
  3. In the upper-middle panel, locate each {Task Name} values listed above in the Name column.
  4. In the lower-middle panel, click the Actions tab. In the Details column, check for the {Task to be run} string.
  5. If the said string is found, delete the task.

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.
  • %User Temp%\end.bat
  • %User Temp%\start
  • %User Temp%\SetTaskPathDl.exe
  • %User Temp%\Microsoft.Win32.TaskScheduler.dll
  • %User Temp%\drmanidd32.dll
  • %Application Data%\Adobe\Update\SecuUpdates.dll

Step 6

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