Analysis by: Wilbert Vidal
ALIASES:

Trojan.Win32.KillProc.fdsssz (NANO-Antivirus); TrojanDownloader:Win32/Spejandr (Microsoft)

 PLATFORM:

Windows

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 SYSTEM IMPACT RATING:
 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 the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system. As of this writing, the said sites are inaccessible.

  TECHNICAL DETAILS

File Size: 183,264 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 08 Jun 2018

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 adds the following folders:

  • %ProgramData%\Settings

(Note: %ProgramData% is a version of the Program Files folder where any user on a multi-user computer can make changes to programs. This contains application data for all users. This is usually C:\ProgramData on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit), or C:\Documents and Settings\All Users on Windows Server 2003(32-bit), 2000(32-bit) and XP.)

Other System Modifications

This Backdoor deletes the following files:

  • %ProgramData%\AMMYY\wmihost.exe
  • %ProgramData%\AMMYY\settings3.bin
  • %ProgramData%\Foundation\wmites.exe
  • %ProgramData%\Foundation\settings3.bin
  • %ProgramData%\Foundation1\wmites.exe
  • %ProgramData%\Foundation1\settings3.bin
  • %ProgramData%\Microsoft\wsus.exe
  • %ProgramData%\Microsoft\settings3.bin

(Note: %ProgramData% is a version of the Program Files folder where any user on a multi-user computer can make changes to programs. This contains application data for all users. This is usually C:\ProgramData on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit), or C:\Documents and Settings\All Users on Windows Server 2003(32-bit), 2000(32-bit) and XP.)

It deletes the following folders:

  • %ProgramData%\Settings
  • %ProgramData%\Microsoft\Enc
  • %ProgramData%\AMMYY
  • %ProgramData%\Foundation
  • %ProgramData%\Foundation1

(Note: %ProgramData% is a version of the Program Files folder where any user on a multi-user computer can make changes to programs. This contains application data for all users. This is usually C:\ProgramData on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit), or C:\Documents and Settings\All Users on Windows Server 2003(32-bit), 2000(32-bit) and XP.)

Process Termination

This Backdoor terminates the following processes if found running in the affected system's memory:

  • Wsus.exe

Download Routine

This Backdoor connects to the following website(s) to download and execute a malicious file:

  • http://{BLOCKED}portservice.com/load.png

It saves the files it downloads using the following names:

  • %ProgramData%\Settings\wsus.exe

(Note: %ProgramData% is a version of the Program Files folder where any user on a multi-user computer can make changes to programs. This contains application data for all users. This is usually C:\ProgramData on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit), or C:\Documents and Settings\All Users on Windows Server 2003(32-bit), 2000(32-bit) and XP.)

It then executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.

As of this writing, the said sites are inaccessible.

Other Details

This Backdoor does the following:

  • it checks for the following AV related running processes:
    • BullGuard.exe
    • Bdss.exe
    • Bdagent.exe
    • V3Main.exe
    • V3SP.exe
    • PSVMain.exe
  • it executes the following commands:
    • /C net.exe stop ammyy
    • /C sc delete ammyy
    • /C net.exe stop foundation
    • /C sc delete foundation
    • /c del {malware path}\1.exe >> NUL
    • /C sc create foundation binPath= ""%ProgramData%\Settings\wsus.exe -service"" type= own start= auto e
    • /C net.exe start foundation y

(Note: %ProgramData% is a version of the Program Files folder where any user on a multi-user computer can make changes to programs. This contains application data for all users. This is usually C:\ProgramData on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit), or C:\Documents and Settings\All Users on Windows Server 2003(32-bit), 2000(32-bit) and XP.)

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 14.308.06
FIRST VSAPI PATTERN DATE: 08 Jun 2018
VSAPI OPR PATTERN File: 14.309.00
VSAPI OPR PATTERN Date: 09 Jun 2018

Step 1

Before doing any scans, Windows 7, Windows 8, Windows 8.1, and Windows 10 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

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.
  • %ProgramData%\Settings

Step 4

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