Backdoor.Win32.NANOCORE.TIDY

January 07, 2020
 ALIASES:

Trojan:Win32/Nanocore.BA!MTB (Microsoft); HEUR:Trojan-Dropper.Win32.Generic (Kaspersky)

 PLATFORM:

Windows

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted:

  • 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.

  TECHNICAL DETAILS

File Size:

1,419,726 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

07 Jan 2020

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 processes:

  • "%Program Files%\Microsoft Office\Office12\WINWORD.EXE" /n /dde
  • %User Temp%\63635475\ADAOBI CV.docx L'expression commerce triangulaire ne doit pas se r\xc3\x83\xc2\xa9duire uniquement \xc3\x83\xc2\xa0 un passage en trois temps sur trois continents :
  • %User Temp%\63635475\qqpgdwlsk.pif ugarrwuhex.fgp
  • %Windows%\splwow64.exe 12288

(Note: %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000(32-bit), Server 2003(32-bit), XP, Vista(64-bit), 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit) , or C:\Program Files (x86) in Windows XP(64-bit), Vista(64-bit), 7(64-bit), 8(64-bit), 8.1(64-bit), 2008(64-bit), 2012(64-bit) and 10(64-bit).. %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.)

It creates the following folders:

  • %System Root%\Users
  • %Application Data%\0EFADD19-2A94-41FB-8931-F2BBC5D61333\Logs
  • %Application Data%\0EFADD19-2A94-41FB-8931-F2BBC5D61333\Logs\{username}
  • %Application Data%\0EFADD19-2A94-41FB-8931-F2BBC5D61333
  • %User Profile%\AppData
  • %User Temp%\63635475
  • %User Profile%\temp

(Note: %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.. %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name} on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

Other System Modifications

This Backdoor adds the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
FileExts\DDECache

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
FileExts\DDECache\WinWord\
System

HKEY_CURRENT_USER\Software\Microsoft\
Shared Tools\Proofing Tools\Grammar\
MSGrammar\3.0\2057

It adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
FileExts\DDECache\WinWord\
System
ProcessName = "WINWORD.EXE"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
FileExts\DDECache\WinWord\
System
WindowName = "Microsoft Word"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
FileExts\DDECache\WinWord\
System
WindowClassName = "OpusApp"

HKEY_CURRENT_USER\Software\Microsoft\
Shared Tools\Proofing Tools\Grammar\
MSGrammar\3.0\2057
Options Version = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\
Microsoft\Windows\CurrentVersion\
Run
expl0rer = "%User Temp%\63635475\QQPGDW~1.PIF %User Temp%\63635475\UGARRW~1.FGP"

Dropping Routine

This Backdoor drops the following files:

  • %User Temp%\63635475\dkkp.bin
  • %User Temp%\63635475\ltbcqanoha.pdf
  • %User Temp%\63635475\fdmqwqhhj.xml
  • %User Temp%\63635475\xhadavvqnf.log
  • %User Temp%\63635475\xbmbjars.bin
  • %Application Data%\Microsoft\UProof\ExcludeDictionaryEN4409.lex
  • %User Temp%\63635475\gaduodih.mp3
  • %User Profile%\temp\ariufhkuc.bin
  • %All Users Profile%\Microsoft\OFFICE\DATA\opa12.dat
  • %User Temp%\63635475\ksroqjlee.xml
  • %User Temp%\63635475\eunvn.dat
  • %User Temp%\63635475\xvnt.dll
  • %User Temp%\63635475\wlit.dat
  • %User Temp%\63635475\uanf.dll
  • %User Temp%\63635475\nbvbeq.msc
  • %User Temp%\63635475\injt.ppt
  • %User Temp%\63635475\fmckor.jpg
  • %Application Data%\Microsoft\UProof\CUSTOM.DIC
  • %User Temp%\63635475\jlfrmwjjj.cpl
  • %User Temp%\63635475\ghqoxdgkvq.exe
  • %User Temp%\63635475\vhtlwmxm.docx
  • %User Temp%\63635475\fgesusm.jpg
  • %User Temp%\63635475\vdumljxt.docx
  • %User Temp%\63635475\kdjc.jpg
  • %User Temp%\63635475\hqfd.icm
  • %User Temp%\63635475\sqrphiv.ppt
  • %User Temp%\63635475\qknpcl.xml
  • %User Temp%\63635475\virxq.msc
  • %User Temp%\63635475\ugarrwuhex.fgp
  • %User Temp%\63635475\eipajqh.jpg
  • %User Temp%\63635475\dfrdbuopk.xls
  • %User Temp%\63635475\xdgphwqoh.docx
  • %User Temp%\63635475\xmfjvia.bin
  • %User Temp%\63635475\xhrqhgb.jpg
  • %User Temp%\63635475\isxngqxtm.exe
  • %User Temp%\63635475\usupkfiis.xl
  • %User Temp%\63635475\usqvssb.docx
  • %User Temp%\63635475\vjxk.msc
  • %User Temp%\63635475\gcxxfhm.txt
  • %Application Data%\Microsoft\Templates\Normal.dotm
  • %User Temp%\63635475\qqpgdwlsk.pif
  • %User Temp%\63635475\ccapomir.xl
  • %User Temp%\63635475\fnsma.ini
  • %User Temp%\63635475\aiiei.dll
  • %User Temp%\63635475\dopxhlr.txt
  • %User Temp%\63635475\ehas.bmp
  • %User Temp%\63635475\tgdvmldpnb.mp3
  • %User Temp%\63635475\igaaqnilg.bin
  • %User Temp%\63635475\jnmmvktnlq.log
  • %User Temp%\63635475\uilrwrbia.xml
  • %User Temp%\63635475\ntwt.pdf
  • %User Temp%\63635475\jnsxbth.docx
  • %User Temp%\63635475\ariufhkuc.bin
  • %User Temp%\63635475\epvopapa.docx
  • %User Temp%\63635475\nmmlflrq.ppt
  • %User Temp%\63635475\hlodoakcuf.bin
  • %User Temp%\63635475\hhmur.jpg
  • %Application Data%\0EFADD19-2A94-41FB-8931-F2BBC5D61333\run.dat
  • %User Temp%\63635475\ADAOBI CV.docx
  • %User Temp%\63635475\aoihfubrc.cpl
  • %User Temp%\63635475\~$AOBI CV.docx
  • %User Temp%\63635475\tsocd.ppt
  • %User Temp%\RegSvcs.exe
  • %User Temp%\63635475\bsrpwid.pdf

(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(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name} on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %All Users Profile% is the common user's profile folder, which is usually C:\Documents and Settings\All Users on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\ProgramData on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit). )

Other Details

This Backdoor connects to the following possibly malicious URL:

  • http://sirfox.{BLOCKED}s.org

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.850

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

Identify and terminate files detected as Backdoor.Win32.NANOCORE.TIDY

[ 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 3

Delete this registry key

[ 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\Explorer\FileExts
    • DDECache
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\DDECache\WinWord
    • System
  • In HKEY_CURRENT_USER\Software\Microsoft\Shared Tools\Proofing Tools\Grammar\MSGrammar\3.0
    • 2057

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\Explorer\FileExts\DDECache\WinWord\System
    • ProcessName = "WINWORD.EXE"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\DDECache\WinWord\System
    • WindowName = "Microsoft Word"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\DDECache\WinWord\System
    • WindowClassName = "OpusApp"
  • In HKEY_CURRENT_USER\Software\Microsoft\Shared Tools\Proofing Tools\Grammar\MSGrammar\3.0\2057
    • Options Version = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Windows\CurrentVersion\Run
    • expl0rer = "%User Temp%\63635475\QQPGDW~1.PIF %User Temp%\63635475\UGARRW~1.FGP"

Step 5

Search and delete these components

[ Learn More ]
There may be some components 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%\63635475\dkkp.bin
  • %User Temp%\63635475\ltbcqanoha.pdf
  • %User Temp%\63635475\fdmqwqhhj.xml
  • %User Temp%\63635475\xhadavvqnf.log
  • %User Temp%\63635475\xbmbjars.bin
  • %Application Data%\Microsoft\UProof\ExcludeDictionaryEN4409.lex
  • %User Temp%\63635475\gaduodih.mp3
  • %User Profile%\temp\ariufhkuc.bin
  • %All Users Profile%\Microsoft\OFFICE\DATA\opa12.dat
  • %User Temp%\63635475\ksroqjlee.xml
  • %User Temp%\63635475\eunvn.dat
  • %User Temp%\63635475\xvnt.dll
  • %User Temp%\63635475\wlit.dat
  • %User Temp%\63635475\uanf.dll
  • %User Temp%\63635475\nbvbeq.msc
  • %User Temp%\63635475\injt.ppt
  • %User Temp%\63635475\fmckor.jpg
  • %Application Data%\Microsoft\UProof\CUSTOM.DIC
  • %User Temp%\63635475\jlfrmwjjj.cpl
  • %User Temp%\63635475\ghqoxdgkvq.exe
  • %User Temp%\63635475\vhtlwmxm.docx
  • %User Temp%\63635475\fgesusm.jpg
  • %User Temp%\63635475\vdumljxt.docx
  • %User Temp%\63635475\kdjc.jpg
  • %User Temp%\63635475\hqfd.icm
  • %User Temp%\63635475\sqrphiv.ppt
  • %User Temp%\63635475\qknpcl.xml
  • %User Temp%\63635475\virxq.msc
  • %User Temp%\63635475\ugarrwuhex.fgp
  • %User Temp%\63635475\eipajqh.jpg
  • %User Temp%\63635475\dfrdbuopk.xls
  • %User Temp%\63635475\xdgphwqoh.docx
  • %User Temp%\63635475\xmfjvia.bin
  • %User Temp%\63635475\xhrqhgb.jpg
  • %User Temp%\63635475\isxngqxtm.exe
  • %User Temp%\63635475\usupkfiis.xl
  • %User Temp%\63635475\usqvssb.docx
  • %User Temp%\63635475\vjxk.msc
  • %User Temp%\63635475\gcxxfhm.txt
  • %Application Data%\Microsoft\Templates\Normal.dotm
  • %User Temp%\63635475\qqpgdwlsk.pif
  • %User Temp%\63635475\ccapomir.xl
  • %User Temp%\63635475\fnsma.ini
  • %User Temp%\63635475\aiiei.dll
  • %User Temp%\63635475\dopxhlr.txt
  • %User Temp%\63635475\ehas.bmp
  • %User Temp%\63635475\tgdvmldpnb.mp3
  • %User Temp%\63635475\igaaqnilg.bin
  • %User Temp%\63635475\jnmmvktnlq.log
  • %User Temp%\63635475\uilrwrbia.xml
  • %User Temp%\63635475\ntwt.pdf
  • %User Temp%\63635475\jnsxbth.docx
  • %User Temp%\63635475\ariufhkuc.bin
  • %User Temp%\63635475\epvopapa.docx
  • %User Temp%\63635475\nmmlflrq.ppt
  • %User Temp%\63635475\hlodoakcuf.bin
  • %User Temp%\63635475\hhmur.jpg
  • %Application Data%\0EFADD19-2A94-41FB-8931-F2BBC5D61333\run.dat
  • %User Temp%\63635475\ADAOBI CV.docx
  • %User Temp%\63635475\aoihfubrc.cpl
  • %User Temp%\63635475\~$AOBI CV.docx
  • %User Temp%\63635475\tsocd.ppt
  • %User Temp%\RegSvcs.exe
  • %User Temp%\63635475\bsrpwid.pdf

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.
  • %System Root%\Users
  • %Application Data%\0EFADD19-2A94-41FB-8931-F2BBC5D61333\Logs
  • %Application Data%\0EFADD19-2A94-41FB-8931-F2BBC5D61333\Logs\{username}
  • %Application Data%\0EFADD19-2A94-41FB-8931-F2BBC5D61333
  • %User Profile%\AppData
  • %User Temp%\63635475
  • %User Profile%\temp

Step 7

Scan your computer with your Trend Micro product to delete files detected as Backdoor.Win32.NANOCORE.TIDY. 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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