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BKDR_SHELL.NTW

January 17, 2013
 Analysis by: Rhena Inocencio
 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: Backdoor

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Dropped by other malware, Downloaded from the Internet


This backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites. It may be downloaded by other malware/grayware from remote sites.

  TECHNICAL DETAILS

File Size:

35,416 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

17 Jan 2013

Payload:

Connects to URLs/IPs

Arrival Details

This backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It may be downloaded by the following malware/grayware from remote sites:

  • JAVA_DLOADER.NTW

It may be downloaded from the following remote site(s):

  • http://{BLOCKED}lcurrencyreport.com/cybercrime-suspect-arrested/up1.exe

Installation

This backdoor drops the following copies of itself into the affected system and executes them:

  • {All Users Profile}\svchost.exe

Autostart Technique

This backdoor adds the following registry entries to enable its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
SunJavaUpdateSched = "{All Users Profile}\svchost.exe"

NOTES:

This backdoor opens port 8000 where it listens for remote connection. Once a connection is established, it gives the remote user a command shell access to the affected system.

It checks if it is running under a virtual environment by querying the following registry key:

  • HKEY_LOCAL_MACHINE\System\currentcontrolset\Services\Disk\Enum

It terminates itself if the following strings on the aforementioned registry are present:

  • VBOX
  • Virtual
  • VMware

  SOLUTION

Minimum Scan Engine:

9.300

FIRST VSAPI PATTERN FILE:

9.662.02

FIRST VSAPI PATTERN DATE:

17 Jan 2013

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

Remove malware/grayware files that dropped/downloaded BKDR_SHELL.NTW

Step 3

Scan your computer with your Trend Micro product and note files detected as BKDR_SHELL.NTW

Step 4

Restart in Safe Mode

[ Learn More ]

Step 5

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\Run
    • SunJavaUpdateSched = "{All Users Profile}\svchost.exe"

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_SHELL.NTW. 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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