TROJ_POSADOR.SB

 Analysis by: Sabrina Lei Sioting

 PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW


This Trojan executes the dropped file(s). As a result, malicious routines of the dropped files are exhibited on the affected system.

It deletes the initially executed copy of itself.

  TECHNICAL DETAILS

File Size:

163,840 bytes

Memory Resident:

Yes

Initial Samples Received Date:

06 Apr 2011

Installation

This Trojan drops the following non-malicious files:

  • %System%\{random}.dat
  • %System%\{random1}.dat
  • %System%\{random2}.dat
  • %System%\{random3}.dat

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)

Other System Modifications

This Trojan adds the following registry entries as part of its installation routine:

HKEY_CLASSES_ROOT\CLSID\{CLSID}
@ = "{random}"

HKEY_CLASSES_ROOT\CLSID\{CLSID}\
InprocServer32
@ = "%System%\{random}.ocx"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{CLSID}
@ = "{random}"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{CLSID}\InprocServer32
@ = "%System%\{random}.ocx"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
ShellIconOverlayIdentifiers\{random}
@ = "{CLSID}"

It adds the following registry keys as part of its installation routine:

HKEY_CLASSES_ROOT\CLSID\{CLSID}

HKEY_CLASSES_ROOT\CLSID\{CLSID}\
InprocServer32

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{CLSID}

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{CLSID}\InprocServer32

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
ShellIconOverlayIdentifiers\{random}

Dropping Routine

This Trojan drops the following files:

  • %System%\{random}.ocx
  • %User Temp%\{random}.tmp

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.. %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, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

It executes the dropped file(s). As a result, malicious routines of the dropped files are exhibited on the affected system.

Other Details

This Trojan deletes the initially executed copy of itself

  SOLUTION

Minimum Scan Engine:

9.300

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

Step 2

Identify and terminate files detected as TROJ_POSADOR.SB

[ Learn More ]
  1. Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

Step 3

Delete the random registry key/s that this malware created

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator’s help. You may also check out this Microsoft article first before modifying your computer's registry.

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. 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\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\ShellIconOverlayIdentifiers
    • {random}

Step 5

Search and delete the file detected as TROJ_POSADOR.SB

[ Learn More ]

Step 6

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