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BKDR_NETWIRED.XXL

April 12, 2016
 Analysis by: Pearl Charlaine Espejo
 ALIASES:

Win32.Backdoor.Netwire.Kiuy (Tencent)

 PLATFORM:

Windows

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet, Dropped by other malware


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

  TECHNICAL DETAILS

File Size:

151,552 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

11 Apr 2016

Payload:

Steals information, 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.

Installation

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

  • %Application Data%\Install\Host.exe

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

It drops the following files:

  • %User Temp%\subfolder\hfgfhdg.exe - modified copy of itself
  • %Application Data%\Install\.Identifier

(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.. %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

It adds the following mutexes to ensure that only one of its copies runs at any one time:

  • hEGpnAVx

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
NetWire = "%Application Data%\Install\Host.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{4J0HKAK2-LMY3-NXM3-5GYE-6AYHF5Y0FH30}
StubPath = "%Application Data%\Install\Host.exe"

It drops the following file(s) in the Windows User Startup folder to enable its automatic execution at every system startup:

  • hfgfhdg.vbs

Backdoor Routine

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

  • Download & execute files on the affected system
  • Execute Command Shell
  • List files on a directory
  • Terminate Processes
  • Perform keylogging routine

It connects to the following URL(s) to send and receive commands from a remote malicious user:

  • {BLOCKED}.{BLOCKED}.131.212:3365

Dropping Routine

This backdoor drops the following file(s), which it uses for its keylogging routine:

  • %Application Data%\Logs\{DD-MM-YYYY}

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

Information Theft

This backdoor attempts to steal stored email credentials from the following:

  • Windows Live Mail
  • Microsoft Outlook

It attempts to get stored information such as user names, passwords, and hostnames from the following browsers:

  • Mozilla Firefox
  • Mozilla Thunderbird
  • Mozilla SeaMonkey
  • Opera
  • Internet Explorer
  • Google Chrome

  SOLUTION

Minimum Scan Engine:

9.8

FIRST VSAPI PATTERN FILE:

12.462.05

FIRST VSAPI PATTERN DATE:

12 Apr 2016

VSAPI OPR PATTERN File:

12.463.00

VSAPI OPR PATTERN Date:

13 Apr 2016

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

Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.

Step 3

Restart in Safe Mode

[ Learn More ]

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\Run
    • NetWire = "%Application Data%\Install\Host.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Active Setup\Installed Components\{4J0HKAK2-LMY3-NXM3-5GYE-6AYHF5Y0FH30}
    • StubPath = "%Application Data%\Install\Host.exe"

Step 5

Search and delete this file

[ Learn More ]
There may be some 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.
  • %Application Data%\Install\.Identifier
  • %Application Data%\Logs\{DD-MM-YYYY}
  • %User Temp%\subfolder\hfgfhdg.exe
  • %User Startup%\hfgfhdg.vbs

Step 6

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