Trojan.Win32.AGENT.AT

February 12, 2020
 ALIASES:

BAT/Agent.z (McAfee); Trojan.Win32.Agent.xadbit (Kaspersky)

 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • 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.

  TECHNICAL DETAILS

File Size:

245,896 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

12 Feb 2020

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.

Installation

This Trojan adds the following processes:

  • cmd /c install.bat
  • xcopy /c /q /y %User Temp%\IXP001.TMP\*.dll %Application Data%\Downloader
  • cmd /c %Application Data%\Downloader\run.bat
  • reg add "HKCU\Software\Microsoft\Windows\CurrentVersion\Run" /v "Audio Driver" /t "REG_SZ" /d "\"%Application Data%\AudioDriver\run.bat\"" /f
  • fsutil dirty query %System Root%
  • rundll32 %Application Data%\Downloader\c2mp3runner.dll,Start
  • %User Temp%\0.exe 1
  • %Application Data%\AudioDriver\run.bat
  • sc.exe failure "Windows Backup Scheduler" reset= 3600 actions= restart/1000/restart/1000/restart/1000
  • %Windows%\msfw.exe t
  • rundll32 %Application Data%\AudioDriver\0.dll,Start
  • %Windows%\windows_update.exe
  • %Windows%\Microsoft.NET\Framework\v4.0.30319\mscorsvw.exe
  • %System%\svchost.exe -k LocalServiceAndNoImpersonation
  • %Windows%\Microsoft.NET\Framework64\v4.0.30319\mscorsvw.exe
  • %System%\sppsvc.exe
  • "%System Root%\Program Files\Windows Media Player\wmpnetwk.exe"
  • %Application Data%\AudioDriver\install.bat
  • reg add "HKCU\Software\Microsoft\Windows\CurrentVersion\Run" /v "Audio Driver" /t "REG_SZ" /d "rundll32.exe %Application Data%\AudioDriver\0.dll,Start" /f
  • certutil -addstore Root %Windows%\Temp\TS_RR1.1933.tmp3

(Note: %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).. %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.. %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.. %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

It creates the following folders:

  • %Application Data%\Downloader
  • %Application Data%\Downloader\Downloads
  • %Windows%\ServiceProfiles\NetworkService\AppData\Local\Microsoft
  • %Application Data%\AudioDriver
  • %Application Data%\chrome-addon

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

Autostart Technique

This Trojan registers itself as a system service to ensure its automatic execution at every system startup by adding the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Windows Backup Scheduler
ImagePath = "%Windows%\windows_update.exe"

It adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
Audio Driver = "%Application Data%\AudioDriver\run.bat"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
Microsoft Windows Firewall = "%Windows%\msfw.exe t"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
Audio Driver = "rundll32.exe %Application Data%\AudioDriver\0.dll,Start"

Other System Modifications

This Trojan deletes the following files:

  • %Windows%\cer558E.tmp

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

It deletes the following folders:

  • %All Users Profile%\ie11history.db
  • %User Temp%\IXP001.TMP
  • %Windows%\msfw.exe
  • %Windows%\windows_update.exe

(Note: %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). . %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 adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\
Microsoft\Windows\CurrentVersion\
RunOnce
wextract_cleanup0 = "rundll32.exe %System%\advpack.dll,DelNodeRunDLL32 "%User Temp%\IXP001.TMP\""

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\Windows Backup Scheduler
FailureActions = "{random characters}"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
SystemCertificates\ROOT\Certificates\
C0CA09074B3859DD50AE4B0A1DB67EC90137EBC7
Blob = "{random characters}"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\NetworkList\
Nla\Cache\Intranet
{89BCDCB3-5725-45A2-94AB-2D6B641209B0} = "\x00PV\xbcK\xa3"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center
cval = "0"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Windows Backup Scheduler
DisplayName = "Windows Backup Scheduler"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Windows Backup Scheduler
Start = "SERVICE_AUTO_START"

It deletes the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\
Microsoft\Windows\CurrentVersion\
RunOnce\wextract_cleanup0

Dropping Routine

This Trojan drops the following files:

  • %Windows%\microsoft-edge.vbs
  • %Application Data%\chrome-addon\addon.js
  • %Application Data%\AudioDriver\install.bat
  • %All Users Profile%\Microsoft\Windows\DRM\drmstore.hds
  • %AppDataLocal%\Microsoft\Media Player\CurrentDatabase_372.wmdb
  • %Windows%\Temp\TS_RR1.1933.tmp3
  • %Windows%\perflog.dat
  • %Windows%\msfw.exe
  • %Application Data%\chrome-addon\manifest.json
  • %All Users Profile%\Microsoft\Windows\DRM\v3ks.sec
  • %All Users Profile%\ie11history.db
  • %Application Data%\AudioDriver\run.bat
  • %Application Data%\Downloader\install.bat
  • %Windows%\windows_update.exe
  • %Windows%\microsoft_original_software.chk
  • %Application Data%\Downloader\run.bat
  • %Application Data%\Downloader\c2mp3runner.dll

(Note: %Windows% is the Windows folder, where it usually is C:\Windows 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).. %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). . %AppDataLocal% is the Local Application Data folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://www.{BLOCKED}oft.com/pki/certs/MicRooCerAut_2010-06-23.crt
  • http://{BLOCKED}3.to
  • http://ad.{BLOCKED}x.com
  • http://ad1.{BLOCKED}x.com
  • http://ad2.{BLOCKED}x.com
  • http://ad3.{BLOCKED}x.com

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

Restart in Safe Mode

[ Learn More ]

Step 3

Identify and terminate files detected as Trojan.Win32.AGENT.AT

[ 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

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\Run
    • Audio Driver = "%Application Data%\AudioDriver\run.bat"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • Microsoft Windows Firewall = "%Windows%\msfw.exe t"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • Audio Driver = "rundll32.exe %Application Data%\AudioDriver\0.dll,Start"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Windows\CurrentVersion\RunOnce
    • wextract_cleanup0 = "rundll32.exe %System%\advpack.dll,DelNodeRunDLL32 "%User Temp%\IXP001.TMP\""
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\Windows Backup Scheduler
    • FailureActions = "{random characters}"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\SystemCertificates\ROOT\Certificates\C0CA09074B3859DD50AE4B0A1DB67EC90137EBC7
    • Blob = "{random characters}"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\NetworkList\Nla\Cache\Intranet
    • {89BCDCB3-5725-45A2-94AB-2D6B641209B0} = "\x00PV\xbcK\xa3"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Security Center
    • cval = "0"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Windows Backup Scheduler
    • DisplayName = "Windows Backup Scheduler"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Windows Backup Scheduler
    • Start = "SERVICE_AUTO_START"

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.
  • %Windows%\microsoft-edge.vbs
  • %Application Data%\chrome-addon\addon.js
  • %Application Data%\AudioDriver\install.bat
  • %All Users Profile%\Microsoft\Windows\DRM\drmstore.hds
  • %AppDataLocal%\Microsoft\Media Player\CurrentDatabase_372.wmdb
  • %Windows%\Temp\TS_RR1.1933.tmp3
  • %Windows%\perflog.dat
  • %Windows%\msfw.exe
  • %Application Data%\chrome-addon\manifest.json
  • %All Users Profile%\Microsoft\Windows\DRM\v3ks.sec
  • %All Users Profile%\ie11history.db
  • %Application Data%\AudioDriver\run.bat
  • %Application Data%\Downloader\install.bat
  • %Windows%\windows_update.exe
  • %Windows%\microsoft_original_software.chk
  • %Application Data%\Downloader\run.bat
  • %Application Data%\Downloader\c2mp3runner.dll

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.
  • %Application Data%\Downloader
  • %Application Data%\Downloader\Downloads
  • %Windows%\ServiceProfiles\NetworkService\AppData\Local\Microsoft
  • %Application Data%\AudioDriver
  • %Application Data%\chrome-addon

Step 7

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

Step 8

Restore this file from backup only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on you computer again.

  • %Windows%\cer558E.tmp

Step 9

Restore these deleted registry keys/values from backup

*Note: Only Microsoft-related keys/values will be restored. If the malware/grayware also deleted registry keys/values related to programs that are not from Microsoft, please reinstall those programs on your computer.

  • In HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Windows\CurrentVersion\RunOnce
    • wextract_cleanup0


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