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TROJ_DROPPER
Aliases: Trojan:BAT/Banker.F, Trojan:BAT/Banker.F (Microsoft); Generic PWS.wm (McAfee); Trojan.ADH (Symantec); ARC:RAR, PAK:[AxUpdateMS.exe]:UPX, ARC:[AxUpdateMS.exe]:BatToExe, [AxUpdateMS.exe/devil.bat]:Trojan- (Kaspersky); ERROR (Sunbelt)
Malware type: Trojan
Destructive: No
Platform: Windows 2000, Windows XP, Windows Server 2003
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: 123,969 bytes
File type: EXE
Memory resident: Yes
Initial samples received date: 03 Jan 2012

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 creates the following folders:

  • %System Root%\DOCUME~1
  • %System Root%\DOCUME~1\ADMINI~1
  • %User Profile%\LOCALS~1
  • %User Temp%\1.tmp

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.. %User Profile% is the current user's profile folder, which is usually C:\Windows\Profiles\{user name} on Windows 98 and ME, C:\WINNT\Profiles\{user name} on Windows NT, and C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003.. %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.)

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
ActiveX Update = "%User Temp%\AxUpdateMS.exe"

Other System Modifications

This Trojan deletes the following files:

  • %User Temp%\1.tmp

(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.)

It adds the following registry keys:

HKEY_CURRENT_USER\Software\WinRAR SFX

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\Internet Explorer\Control Panel

HKEY_CURRENT_USER\SOFTWARE\Policies\
Microsoft\Internet Explorer\Control Panel

It adds the following registry entries:

HKEY_CURRENT_USER\Software\WinRAR SFX
C%%DOCUME~1%ADMINI~1%LOCALS~1%Temp% = "%User Temp%\"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Internet Settings
AutoConfigUrl = "file://%User Temp%/KB_BRIAN-372130D4D.txt"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Internet Settings
EnableHttp1_1 = 1

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\Internet Explorer\Control Panel
AdvancedTab = 1

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\Internet Explorer\Control Panel
ResetWebSettings = 1

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\Internet Explorer\Control Panel
Autoconfig = 1

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
AutoConfigUrl = "file://%User Temp%/KB_BRIAN-372130D4D.txt"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
EnableHttp1_1 = 1

HKEY_CURRENT_USER\Software\Policies\
Microsoft\Internet Explorer\Control Panel
Autoconfig = 1

HKEY_CURRENT_USER\Software\Policies\
Microsoft\Internet Explorer\Control Panel
AdvancedTab = 1

HKEY_CURRENT_USER\Software\Policies\
Microsoft\Internet Explorer\Control Panel
ResetWebSettings = 1

Dropping Routine

This Trojan drops the following files:

  • __tmp_rar_sfx_access_check_36265
  • AxUpdateMS.exe
  • %User Temp%\x19.db
  • %User Temp%\t13774.vbs
  • %User Temp%.\KB_BRIAN-372130D4D.txt

(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.)

This report is generated via an automated analysis system.

Solution


Minimum scan engine: 9.200

Step 1

For Windows XP and Windows Server 2003 users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.

Step 2

Restart in Safe Mode

[ Learn more ]

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
    • WinRAR SFX
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Internet Explorer
    • Control Panel
  • In HKEY_CURRENT_USER\SOFTWARE\Policies\Microsoft\Internet Explorer
    • Control Panel

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • ActiveX Update="%User Temp%\AxUpdateMS.exe"
  • In HKEY_CURRENT_USER\Software\WinRAR SFX
    • C%%DOCUME~1%ADMINI~1%LOCALS~1%Temp%="%User Temp%\"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings
    • AutoConfigUrl="file://%User Temp%/KB_BRIAN-372130D4D.txt"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings
    • EnableHttp1_1=1
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Internet Explorer\Control Panel
    • AdvancedTab=1
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Internet Explorer\Control Panel
    • ResetWebSettings=1
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Internet Explorer\Control Panel
    • Autoconfig=1
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
    • AutoConfigUrl="file://%User Temp%/KB_BRIAN-372130D4D.txt"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
    • EnableHttp1_1=1
  • In HKEY_CURRENT_USER\Software\Policies\Microsoft\Internet Explorer\Control Panel
    • Autoconfig=1
  • In HKEY_CURRENT_USER\Software\Policies\Microsoft\Internet Explorer\Control Panel
    • AdvancedTab=1
  • In HKEY_CURRENT_USER\Software\Policies\Microsoft\Internet Explorer\Control Panel
    • ResetWebSettings=1

Step 5

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%\DOCUME~1
  • %System Root%\DOCUME~1\ADMINI~1
  • %User Profile%\LOCALS~1
  • %User Temp%\1.tmp

Step 6

Search and delete these files

[ Learn more ]
There may be some component 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.
  • __tmp_rar_sfx_access_check_36265
  • AxUpdateMS.exe
  • %User Temp%\x19.db
  • %User Temp%\t13774.vbs
  • %User Temp%.\KB_BRIAN-372130D4D.txt

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_DROPPER. 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.
%User Temp%\1.tmp


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Analysis By: Automation

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