TROJ_DROPPER.MNK

October 09, 2012
 Analysis by: Jed Valderama
 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

This Trojan may be dropped by other malware.

It adds services similar to legitimate applications' to trick a user into thinking they are legitimate.

It deletes itself after execution.

  TECHNICAL DETAILS

File Size:

535,840 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

18 Aug 2012

Arrival Details

This Trojan may be dropped by the following malware:

  • TROJ_MDROPR.MNK

Installation

This Trojan adds the following services similar to legitimate applications' to trick a user into thinking they are legitimate:

  • Service Name="AppMgmt"

Autostart Technique

This Trojan registers its dropped component as a system service to ensure its automatic execution at every system startup. It does this by creating the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Internet Explorer\AppMgmt
DisplayName = "Application Management"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Internet Explorer\AppMgmt
ImagePath = "%System%\svchost.exe -k netsvcs"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Enum\Root\LEGACY_APPMGMT\
0000\Control

Other System Modifications

This Trojan deletes the following files:

    It modifies the following registry key(s)/entry(ies) as part of its installation routine:

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
    Intenet Explorer\AppMgmt\Parameters
    ServiceDLL = "%Program Files%\Common Files\ODBC\AppMgmt.dll"

    (Note: The default value data of the said registry entry is "%SystemRoot%\System32\appmgmts.dll".)

    Dropping Routine

    This Trojan drops the following files:

    • %Program Files%\Common Files\DBEngin.EXE - copy of legitimate file Rundll32.exe
    • %Program Files%\Common Files\wuauctl.exe - copy of legitimate file Rundll32.exe
    • %Program Files%\Common Files\ODBC\AppMgmt.dll - detected as TSPY_KAZAF.A
    • %Program Files%\Common Files\ODBC\BITS.dll - detected as TSPY_KAZAF.A
    • %Program Files%\Common Files\ODBC\appmgmt.def
    • %Program Files%\Common Files\ODBC\bits.def

    (Note: %Program Files% is the default Program Files folder, usually C:\Program Files.)

    Other Details

    This Trojan deletes itself after execution.

      SOLUTION

    Minimum Scan Engine:

    9.200

    FIRST VSAPI PATTERN FILE:

    9.330.09

    FIRST VSAPI PATTERN DATE:

    18 Aug 2012

    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

    Scan your computer with your Trend Micro product and note files detected as TROJ_DROPPER.MNK

    Step 3

    Remove malware/grayware files that dropped/downloaded TROJ_DROPPER.MNK

    Step 4

    Remove malware/grayware files dropped/downloaded by TROJ_DROPPER.MNK

      • TSPY_KAZAF.A

    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\Internet Explorer\AppMgmt
      • DisplayName = "Application Management"
    • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\AppMgmt
      • ImagePath = "%System%\svchost.exe -k netsvcs"

    Step 6

    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. Before you could do this, you must restart in Safe Mode. For instructions on how to do this, you may refer to this page If the preceding step requires you to restart in safe mode, you may proceed to edit the system registry.

    • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum\Root\LEGACY_APPMGMT\0000
      • Control

    Step 7

    Restore this modified 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\Intenet Explorer\AppMgmt\Parameters
      • From: ServiceDLL = "%Program Files%\Common Files\ODBC\AppMgmt.dll"
        To: ServiceDLL = "%System%\appmgmts.dll"

    Step 8

    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.
    • %Program Files%\Common Files\DBEngin.EXE
    • %Program Files%\Common Files\wuauctl.exe

    Step 9

    Search and delete this folder

    [ 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.
    • %Program Files%\Common Files\ODBC

    Step 10

    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%\msacm32.drv

    Step 11

    Scan your computer with your Trend Micro product to delete files detected as TROJ_DROPPER.MNK. 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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