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TROJ_DROPPER_0000051.TOMA

October 12, 2012
 ALIASES:

TrojanDownloader:Win32/Tonick.gen!B (Microsoft); Trojan Horse (Symantec); PAK:Armadillo, Trojan-Dropper.Win32.Typic.arx (Kaspersky); Trojan.Win32.Generic!BT (Sunbelt); Trojan.Generic.6138967 (FSecure)

 PLATFORM:

Windows 2000, XP, Server 2003

 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:

1,737,527 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

29 Dec 2011

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:

  • %User Profile%\Application Data\TEMP
  • %User Temp%\instal

(Note: %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.)

Other System Modifications

This Trojan adds the following registry keys:

HKEY_LOCAL_MACHINE\Software\Microsoft\
RFC1156Agent\CurrentVersion\Parameters

HKEY_LOCAL_MACHINE\Software\Licenses

HKEY_CLASSES_ROOT\CLSID\{F557BA3D-A7B9-82B1-467C-B49AA78208E8}

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{F557BA3D-A7B9-82B1-467C-B49AA78208E8}\InprocServer32

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{F557BA3D-A7B9-82B1-467C-B49AA78208E8}\ProgID

HKEY_CURRENT_USER\Software\VB and VBA Program Settings\
tob\x

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
RFC1156Agent\CurrentVersion\Parameters
TrapPollTimeMilliSecs = 3a98

HKEY_LOCAL_MACHINE\SOFTWARE\Licenses
{R7C0DB872A3F777C0} = {random values}

HKEY_LOCAL_MACHINE\SOFTWARE\Licenses
{K7C0DB872A3F777C0} = {random values}

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{F557BA3D-A7B9-82B1-467C-B49AA78208E8}\InprocServer32
ThreadingModel = "Apartment"

HKEY_LOCAL_MACHINE\SOFTWARE\Licenses
{IF41747BB2672C200} = {random values}

HKEY_LOCAL_MACHINE\SOFTWARE\Licenses
{0F41747BB2672C200} = {random values}

HKEY_CURRENT_USER\Software\VB and VBA Program Settings\
tob\x
x = "x"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
WBEM\WDM
%System%\advapi32.dll[MofResourceName] = {random characters}

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
WBEM\WDM
%System%\DRIVERS\ACPI.sys[ACPIMOFResource] = {random characters}

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
WBEM\WDM
%System%\DRIVERS\mssmbios.sys[MofResource] = {random characters}

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
WBEM\WDM
%System%\DRIVERS\intelppm.sys[PROCESSORWMI] = {random characters}

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
WBEM\WDM
%System%\DRIVERS\ipnat.sys[IPNATMofResource] = {random characters}

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
WBEM\WDM
%System%\Drivers\HTTP.sys[UlMofResource] = {random characters}

It deletes the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{F557BA3D-A7B9-82B1-467C-B49AA78208E8}\Version

Dropping Routine

This Trojan drops the following files:

  • %User Temp%\wocualts.exe

(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

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_LOCAL_MACHINE\Software\Microsoft\RFC1156Agent\CurrentVersion
    • Parameters
  • In HKEY_LOCAL_MACHINE\Software
    • Licenses
  • In HKEY_CLASSES_ROOT\CLSID
    • {F557BA3D-A7B9-82B1-467C-B49AA78208E8}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{F557BA3D-A7B9-82B1-467C-B49AA78208E8}
    • InprocServer32
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{F557BA3D-A7B9-82B1-467C-B49AA78208E8}
    • ProgID
  • In HKEY_CURRENT_USER\Software\VB and VBA Program Settings\tob
    • x

Step 3

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\RFC1156Agent\CurrentVersion\Parameters
    • TrapPollTimeMilliSecs=3a98
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Licenses
    • {R7C0DB872A3F777C0}={random values}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Licenses
    • {K7C0DB872A3F777C0}={random values}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{F557BA3D-A7B9-82B1-467C-B49AA78208E8}\InprocServer32
    • ThreadingModel="Apartment"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Licenses
    • {IF41747BB2672C200}={random values}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Licenses
    • {0F41747BB2672C200}={random values}
  • In HKEY_CURRENT_USER\Software\VB and VBA Program Settings\tob\x
    • x="x"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\WBEM\WDM
    • %System%\advapi32.dll[MofResourceName]={random characters}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\WBEM\WDM
    • %System%\DRIVERS\ACPI.sys[ACPIMOFResource]={random characters}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\WBEM\WDM
    • %System%\DRIVERS\mssmbios.sys[MofResource]={random characters}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\WBEM\WDM
    • %System%\DRIVERS\intelppm.sys[PROCESSORWMI]={random characters}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\WBEM\WDM
    • %System%\DRIVERS\ipnat.sys[IPNATMofResource]={random characters}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\WBEM\WDM
    • %System%\Drivers\HTTP.sys[UlMofResource]={random characters}

Step 4

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.
  • %User Profile%\Application Data\TEMP
  • %User Temp%\instal

Step 5

Search and delete this file

[ 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. %User Temp%\wocualts.exe

Step 6

Scan your computer with your Trend Micro product to delete files detected as TROJ_DROPPER_0000051.TOMA. 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 7

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\Classes\CLSID\{F557BA3D-A7B9-82B1-467C-B49AA78208E8}
    • Version


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