Analysis by: Lord Alfred Remorin
ALIASES:

Backdoor.Hikit (Symantec)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel: Downloaded from the Internet, Dropped by other malware

This backdoor may arrive bundled with malware packages as a malware component. It may be dropped by other malware.

It executes commands from a remote malicious user, effectively compromising the affected system.

  TECHNICAL DETAILS

File Size: 262,656 bytes
File Type: DLL
Memory Resident: Yes
Initial Samples Received Date: 21 Aug 2012

Arrival Details

This backdoor may arrive bundled with malware packages as a malware component.

It may be dropped by other malware.

Installation

This backdoor drops the following file(s)/component(s):

It drops the following non-malicious files:

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

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

Backdoor Routine

This backdoor executes the following commands from a remote malicious user:

  • Execute a command shell
  • Open a connection using SOCKS5 proxy
  • Stop execution
  • Transfer files to/from remote server

NOTES:

This backdoor drops the file, %System%\drivers\W7fw.sys, which varies from 32-bit or 64-bit malware depending on the platform of the infected system.

It installs the certificate %Temp%\w7fw.cat on the infected system.

It attempts to Disable Device Driver Signing to successfully install %System%\drivers\W7fw.sys as device driver.

It adds the following registry entries 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"

  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 files dropped/downloaded by BKDR_HIKIT.A

Step 3

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

Step 4

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


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