TROJ_DROPPER.OHX


 ALIASES:

Trojan.Gen (Symantec); PAK:FSG, Trojan-Dropper.Win32.Agent.bizb, Trojan-Dropper.Win32.Agent.bizb (Kaspersky); Trojan.Win32.Generic.pak!cobra (Sunbelt); Trojan.Generic.3686429 (FSecure)

 PLATFORM:

Windows 2000, Windows XP, Windows 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:

30,877 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

24 Nov 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.

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{138B32A2-D4EB-A6D8-14AB-38ACD8369E3E}
StubPath = "%Windows%\Micorsoft.bat"

It registers itself as a BHO to ensure its automatic execution every time Internet Explorer is used by adding the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
Browser Helper Objects\{997DAED0-611B-4631-8F28-3AEE4008974B}

Other System Modifications

This Trojan adds the following registry keys:

HKEY_CURRENT_USER\SOFTWARE\Microsoft\
Internet Explorer\Desktop\longma

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
Browser Helper Objects

HKEY_LOCAL_MACHINE\Software\Microsoft\
Active Setup\Installed Components\{138B32A2-D4EB-A6D8-14AB-38ACD8369E3E}

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{96D7008D-CD5E-44A5-AB7D-8AE001A9CAF6}

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{96D7008D-CD5E-44A5-AB7D-8AE001A9CAF6}\1.0

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{96D7008D-CD5E-44A5-AB7D-8AE001A9CAF6}\1.0\
FLAGS

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{96D7008D-CD5E-44A5-AB7D-8AE001A9CAF6}\1.0\
0

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{96D7008D-CD5E-44A5-AB7D-8AE001A9CAF6}\1.0\
0\win32

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{96D7008D-CD5E-44A5-AB7D-8AE001A9CAF6}\1.0\
HELPDIR

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{D3CA0A59-1914-4B83-AE29-06E4FA36D022}

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{D3CA0A59-1914-4B83-AE29-06E4FA36D022}\ProxyStubClsid

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{D3CA0A59-1914-4B83-AE29-06E4FA36D022}\ProxyStubClsid32

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{D3CA0A59-1914-4B83-AE29-06E4FA36D022}\TypeLib

HKEY_CLASSES_ROOT\CLSID\{997DAED0-611B-4631-8F28-3AEE4008974B}

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{997DAED0-611B-4631-8F28-3AEE4008974B}\InprocServer32

HKEY_CLASSES_ROOT\¹¤³Ì1.IE360

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{D3CA0A59-1914-4B83-AE29-06E4FA36D022}\TypeLib
Version = "1.0"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{997DAED0-611B-4631-8F28-3AEE4008974B}
ProgID = "¹¤³Ì1.IE360"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{997DAED0-611B-4631-8F28-3AEE4008974B}\InprocServer32
ThreadingModel = "Apartment"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{997DAED0-611B-4631-8F28-3AEE4008974B}
TypeLib = "{96D7008D-CD5E-44A5-AB7D-8AE001A9CAF6}"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{997DAED0-611B-4631-8F28-3AEE4008974B}
VERSION = "1.0"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
¹¤³Ì1.IE360
Clsid = "{997DAED0-611B-4631-8F28-3AEE4008974B}"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{D3CA0A59-1914-4B83-AE29-06E4FA36D022}
ProxyStubClsid = "{00020424-0000-0000-C000-000000000046}"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{D3CA0A59-1914-4B83-AE29-06E4FA36D022}
ProxyStubClsid32 = "{00020424-0000-0000-C000-000000000046}"

Dropping Routine

This Trojan drops the following files:

  • %System Root%\bat.bat
  • %Windows%\Micorsoft.bat
  • %System Root%\a.bat

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.. %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.)

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.300

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

Close all opened browser windows

Step 4

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\Internet Explorer\Desktop
    • longma
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer
    • Browser Helper Objects
  • In HKEY_LOCAL_MACHINE\Software\Microsoft\Active Setup\Installed Components
    • {138B32A2-D4EB-A6D8-14AB-38ACD8369E3E}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib
    • {96D7008D-CD5E-44A5-AB7D-8AE001A9CAF6}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib\{96D7008D-CD5E-44A5-AB7D-8AE001A9CAF6}
    • 1.0
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib\{96D7008D-CD5E-44A5-AB7D-8AE001A9CAF6}\1.0
    • FLAGS
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib\{96D7008D-CD5E-44A5-AB7D-8AE001A9CAF6}\1.0
    • 0
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib\{96D7008D-CD5E-44A5-AB7D-8AE001A9CAF6}\1.0\0
    • win32
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib\{96D7008D-CD5E-44A5-AB7D-8AE001A9CAF6}\1.0
    • HELPDIR
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface
    • {D3CA0A59-1914-4B83-AE29-06E4FA36D022}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface\{D3CA0A59-1914-4B83-AE29-06E4FA36D022}
    • ProxyStubClsid
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface\{D3CA0A59-1914-4B83-AE29-06E4FA36D022}
    • ProxyStubClsid32
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface\{D3CA0A59-1914-4B83-AE29-06E4FA36D022}
    • TypeLib
  • In HKEY_CLASSES_ROOT\CLSID
    • {997DAED0-611B-4631-8F28-3AEE4008974B}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{997DAED0-611B-4631-8F28-3AEE4008974B}
    • InprocServer32
  • In HKEY_CLASSES_ROOT
    • ¹¤³Ì1.IE360

Step 5

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\Active Setup\Installed Components\{138B32A2-D4EB-A6D8-14AB-38ACD8369E3E}
    • StubPath = "%Windows%\Micorsoft.bat"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface\{D3CA0A59-1914-4B83-AE29-06E4FA36D022}\TypeLib
    • Version = "1.0"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{997DAED0-611B-4631-8F28-3AEE4008974B}
    • ProgID = "¹¤³Ì1.IE360"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{997DAED0-611B-4631-8F28-3AEE4008974B}\InprocServer32
    • ThreadingModel = "Apartment"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{997DAED0-611B-4631-8F28-3AEE4008974B}
    • TypeLib = "{96D7008D-CD5E-44A5-AB7D-8AE001A9CAF6}"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{997DAED0-611B-4631-8F28-3AEE4008974B}
    • VERSION = "1.0"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\¹¤³Ì1.IE360
    • Clsid = "{997DAED0-611B-4631-8F28-3AEE4008974B}"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface\{D3CA0A59-1914-4B83-AE29-06E4FA36D022}
    • ProxyStubClsid = "{00020424-0000-0000-C000-000000000046}"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface\{D3CA0A59-1914-4B83-AE29-06E4FA36D022}
    • ProxyStubClsid32 = "{00020424-0000-0000-C000-000000000046}"

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.
  • %System Root%\bat.bat
  • %Windows%\Micorsoft.bat
  • %System Root%\a.bat

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_DROPPER.OHX. 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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