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 the Program Data folder, where it usually is C:\Program Files in Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\ProgramData in 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.)

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 the Program Data folder, where it usually is C:\Program Files in Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\ProgramData in 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 deletes the following folders:

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

(Note: %ProgramData% is the Program Data folder, where it usually is C:\Program Files in Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\ProgramData in 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.)

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 the Program Data folder, where it usually is C:\Program Files in Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\ProgramData in 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 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 the Program Data folder, where it usually is C:\Program Files in Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\ProgramData in 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.)

  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 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

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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