Analysis by: Lord Alfred Remorin
 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

Infection Channel: Dropped by other malware

This Trojan installs a service that monitors incoming packets, which allows execution of backdoor commands from BKDR_HIKIT.A on infected systems.

This Trojan may be dropped by other malware.

  TECHNICAL DETAILS

File Size: 27,648 bytes
File Type: SYS
Memory Resident: Yes
Initial Samples Received Date: 21 Aug 2012

Arrival Details

This Trojan may be dropped by the following malware:

  • BKDR_HIKIT.A

NOTES:

This Trojan rrives as a dropped file of BKDR_HIKIT.A malware as %System%\Drivers\W7fw.sys.sys. It also arrives with the following files:

  • %Temp%\w7fw.cat
  • %Temp%\w7fw.inf
  • %Temp%\w7fw_m.inf

It is registered as a device driver that enables it to automatically execute during startup:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W7fw
DisplayName = "W7fw Service"
ErrorControl = "1"
ImagePath = %System%\DRIVERS\W7fw.sys"
Start = "3"
Type = "1"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W7fwMP
ErrorControl = "1"
ImagePath = %System%\DRIVERS\W7fw.sys"
Start = "3"
Type = "1"

Based on analysis of the codes, the service monitors incoming packets which allows execution of backdoor commands from BKDR_HIKIT.A on infected systems.

  SOLUTION

Minimum Scan Engine: 9.200
FIRST VSAPI PATTERN FILE: 9.338.07
FIRST VSAPI PATTERN DATE: 22 Aug 2012
VSAPI OPR PATTERN File: 9.339.00
VSAPI OPR PATTERN Date: 22 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

Remove malware/grayware files that dropped/downloaded RTKT_HIKIT.A

Step 3

Identify and delete files detected as RTKT_HIKIT.A using either the Startup Disk or Recovery Console

[ Learn More ]

Step 4

Delete this registry key

[ 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.

  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • W7fw
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • W7fwMP

Step 5

Scan your computer with your Trend Micro product to delete files detected as RTKT_HIKIT.A. 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 6

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.

  • Network driver

NOTES:

To restore lost Internet connection, re-install the network driver by doing the following:

  1. Open Control Panel. Click Start>Run, type control panel, then press Enter.
  2. Locate and double-click on the System Properties applet.
  3. Go to Hardware tab and double-click on Device Manager.
  4. Double-click on Network adapters and select the network adapter.
  5. Right-click on the network adapter and click Uninstall to uninstall the network adapter.
  6. Locate and uninstall the following mini port adapter related to RTKT_HIKIT.A:
    • WAN Miniport (IP) - W7fw Miniport
    • WAN Miniport (Network Monitor) - W7fw Miniport
  7. On the menu bar, click Scan for hardware changes.
  8. Restart your computer.


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