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TROJ_AGENT_0000176.TOMA

October 31, 2012
 ALIASES:

Trojan:Win32/Linkoptimizer (Microsoft); Spy-Agent.bf.dldr (McAfee); Trojan.Linkoptimizer (Symantec); PAK:UPX (Kaspersky); Trojan.LinkOptimizer (Sunbelt)

 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.

It deletes itself after execution.

  TECHNICAL DETAILS

File Size:

193,024 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

31 Oct 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 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\{E281853C-F457-3527-B294-35A4E6EF76E2}

Other System Modifications

This Trojan deletes the following files:

  • %Temp%\1.tmp
  • %Temp%\2.tmp
  • %Program Files%\Common Files\Adobe\Acrobat\ActiveX\AcroIEHelperShim.dll

(Note: %Temp% is the Windows Temporary folder, which is usually C:\Windows\Temp or C:\WINNT\Temp.. %Program Files% is the default Program Files folder, usually C:\Program Files.)

It adds the following registry keys:

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Uninstall\
{8B76C8E9-EB94-A62E-5762-C7D2577E3D0E}

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{E281853C-F457-3527-B294-35A4E6EF76E2}

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{E43E4DE6-3F2A-DABA-82DF-3A3B59484001}

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{E281853C-F457-3527-B294-35A4E6EF76E2}\InprocServer32

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{E43E4DE6-3F2A-DABA-82DF-3A3B59484001}\InprocServer32

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
hkylj

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
hkylj\{E43E4DE6-3F2A-DABA-82DF-3A3B59484001}

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Internet Explorer\URLSearchHooks

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
nelae

HKEY_CLASSES_ROOT\CLSID\{4C7E5898-C71D-8B0B-A0F8-00D06AFEBEE6}

HKEY_CLASSES_ROOT\CLSID\{4C7E5898-C71D-8B0B-A0F8-00D06AFEBEE6}\
InprocServer32

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
{8B76C8E9-EB94-A62E-5762-C7D2577E3D0E}
DisplayName = "ConnectionKnight"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
{8B76C8E9-EB94-A62E-5762-C7D2577E3D0E}
UninstallString = "{random characters}"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{E281853C-F457-3527-B294-35A4E6EF76E2}\InprocServer32
ThreadingModel = "Apartment"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{E43E4DE6-3F2A-DABA-82DF-3A3B59484001}\InprocServer32
ThreadingModel = "Apartment"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{4C7E5898-C71D-8B0B-A0F8-00D06AFEBEE6}\InprocServer32
ThreadingModel = "Apartment"

It deletes the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{18DF081C-E8AD-4283-A596-FA578C2EBDC3}\InprocServer32

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{18DF081C-E8AD-4283-A596-FA578C2EBDC3}\ProgID

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{18DF081C-E8AD-4283-A596-FA578C2EBDC3}\Programmable

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{18DF081C-E8AD-4283-A596-FA578C2EBDC3}\TypeLib

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{18DF081C-E8AD-4283-A596-FA578C2EBDC3}\VersionIndependentProgID

HKEY_CLASSES_ROOT\CLSID\{18DF081C-E8AD-4283-A596-FA578C2EBDC3}

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
Browser Helper Objects\{18DF081C-E8AD-4283-A596-FA578C2EBDC3}

HKEY_CURRENT_USER\SOFTWARE\Microsoft\
Internet Explorer\URLSearchHooks

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Discardable\PostSetup\Component Categories\
{00021493-0000-0000-C000-000000000046}\Enum

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Discardable\PostSetup\Component Categories\
{00021494-0000-0000-C000-000000000046}\Enum

Dropping Routine

This Trojan drops the following files:

  • %Windows%\qnqsp1.dll
  • %Program Files%\Common Files\Adobe\Acrobat\ActiveX\AcroIEHelperShim.dll.$$$

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

Other Details

This Trojan deletes itself after execution.

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

Close all opened browser windows

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_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Uninstall
    • {8B76C8E9-EB94-A62E-5762-C7D2577E3D0E}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID
    • {E281853C-F457-3527-B294-35A4E6EF76E2}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID
    • {E43E4DE6-3F2A-DABA-82DF-3A3B59484001}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{E281853C-F457-3527-B294-35A4E6EF76E2}
    • InprocServer32
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{E43E4DE6-3F2A-DABA-82DF-3A3B59484001}
    • InprocServer32
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft
    • hkylj
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\hkylj
    • {E43E4DE6-3F2A-DABA-82DF-3A3B59484001}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer
    • URLSearchHooks
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft
    • nelae
  • In HKEY_CLASSES_ROOT\CLSID
    • {4C7E5898-C71D-8B0B-A0F8-00D06AFEBEE6}
  • In HKEY_CLASSES_ROOT\CLSID\{4C7E5898-C71D-8B0B-A0F8-00D06AFEBEE6}
    • InprocServer32

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\Uninstall\{8B76C8E9-EB94-A62E-5762-C7D2577E3D0E}
    • DisplayName = "ConnectionKnight"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\{8B76C8E9-EB94-A62E-5762-C7D2577E3D0E}
    • UninstallString = "{random characters}"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{E281853C-F457-3527-B294-35A4E6EF76E2}\InprocServer32
    • ThreadingModel = "Apartment"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{E43E4DE6-3F2A-DABA-82DF-3A3B59484001}\InprocServer32
    • ThreadingModel = "Apartment"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{4C7E5898-C71D-8B0B-A0F8-00D06AFEBEE6}\InprocServer32
    • ThreadingModel = "Apartment"

Step 5

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.
  • %Windows%\qnqsp1.dll
  • %Program Files%\Common Files\Adobe\Acrobat\ActiveX\AcroIEHelperShim.dll.$
$
Note: To do a search for the following files, right-click Start then click Search... or Find..., depending on the version of Windows you are running. For each file to be deleted, type its file name in the Named input box. In the Look In drop-down list, select My Computer, then press Enter.
  • Once located, select the file then press SHIFT+DELETE to permanently delete the file.
  • Repeat the said steps for all files listed.

    • Step 6

    Scan your computer with your Trend Micro product to delete files detected as TROJ_AGENT_0000176.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 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.

    • %Temp%\1.tmp
    • %Temp%\2.tmp
    • %Program Files%\Common Files\Adobe\Acrobat\ActiveX\AcroIEHelperShim.dll

    Step 8

    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\{18DF081C-E8AD-4283-A596-FA578C2EBDC3}
      • InprocServer32
    • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{18DF081C-E8AD-4283-A596-FA578C2EBDC3}
      • ProgID
    • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{18DF081C-E8AD-4283-A596-FA578C2EBDC3}
      • Programmable
    • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{18DF081C-E8AD-4283-A596-FA578C2EBDC3}
      • TypeLib
    • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{18DF081C-E8AD-4283-A596-FA578C2EBDC3}
      • VersionIndependentProgID
    • In HKEY_CLASSES_ROOT\CLSID
      • {18DF081C-E8AD-4283-A596-FA578C2EBDC3}
    • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Browser Helper Objects
      • {18DF081C-E8AD-4283-A596-FA578C2EBDC3}
    • In HKEY_CURRENT_USER\SOFTWARE\Microsoft\Internet Explorer
      • URLSearchHooks
    • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Discardable\PostSetup\Component Categories\{00021493-0000-0000-C000-000000000046}
      • Enum
    • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Discardable\PostSetup\Component Categories\{00021494-0000-0000-C000-000000000046}
      • Enum


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