Analysis by: Rhena Inocencio

 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 uses Windows Task Scheduler to create a scheduled task that executes the dropped copy.

  TECHNICAL DETAILS

File Size: 83,456 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 31 May 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.

Installation

This Trojan drops the following copies of itself into the affected system:

  • %System Root%\Documents and Settings\All Users\Application Data\{random file name}.exe

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

It uses Windows Task Scheduler to create a scheduled task that executes the dropped copy.

Other System Modifications

This Trojan adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
Zones\3
2500 = "3"

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
DisableScriptDebuggerIE = "yes"

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
Error Dlg Displayed On Every Error = "no"

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
NoProtectedModeBanner = "1"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Schedule
AtTaskMaxHours = "48"

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://{BLOCKED}.{BLOCKED}.163.23/0xabad1dea.php?a=1b3d43f6f94fcd5343482311848d40b3745011ea8a10252802&b=405&c=37006

  SOLUTION

Minimum Scan Engine: 9.200
FIRST VSAPI PATTERN FILE: 9.174.02
FIRST VSAPI PATTERN DATE: 06 Jun 2012
VSAPI OPR PATTERN File: 9.175.00
VSAPI OPR PATTERN Date: 07 Jun 2012

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_AGENT.BCNK

[ 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 Scheduled Tasks added by this malware/grayware

[ Learn More ]

To delete the added Scheduled Task file:

  1. Open the Windows Scheduled Tasks. To do this:
    • On Windows 2000, XP, and Server 2003:
      Click on Start>Programs>Accessories>System Tools>Scheduled Tasks
    • On Windows Vista and 7:
      Click Start>All Programs>Accessories>System Tools>Task Scheduler
  2. Double-click on a .JOB file.
  3. Check if the malware path and file name exists in the job file. To do this:
    • On Windows 2000, XP, and Server 2003:
      Check the value in the Run field
    • On Windows Vista and 7:
      Find the malware path and file name in the Details column of the Action tab
  4. If the above conditions are true, select the .JOB file then press SHIFT+DELETE to permanently delete the file.
  5. Repeat the steps above for the remaining .JOB files.

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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\3
    • 2500 = "3"
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
    • DisableScriptDebuggerIE = "yes"
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
    • Error Dlg Displayed On Every Error = "no"
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
    • NoProtectedModeBanner = "1"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Schedule
    • AtTaskMaxHours = "48"

Step 5

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