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VBS_DUNIHI.TUOC

June 02, 2015
 Analysis by: Joachim Suico
 ALIASES:

Worm:VBS/Jenxcus.DN (Microsoft); VBS.Dunihi (Symantec); BackDoor.Generic_c.AEFR (AVG);

 PLATFORM:

Windows

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Via physical/removable drives, Downloaded from the Internet


This worm arrives via removable drives. It 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.

It gathers certain information on the affected computer.

It connects to certain websites to send and receive information.

  TECHNICAL DETAILS

File Size:

78,209 bytes

File Type:

VBS

Memory Resident:

Yes

Initial Samples Received Date:

01 Feb 2015

Payload:

Connects to URLs/IPs, Steals information

Arrival Details

This worm arrives via removable drives.

It 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 worm drops the following copies of itself into the affected system:

  • %Application Data%\Internet Explorer\iexplore.vbs

(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.)

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
iexplore = "wscript.exe //D "C:\Documents and Settings\winxp.KARLD-WINXP\ Application Data\Internet Explorer\iexplore.vbs""

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
iexplore = "wscript.exe //D "C:\Documents and Settings\winxp.KARLD-WINXP\ Application Data\Internet Explorer\iexplore.vbs""

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

  • %User Startup%\iexplore.lnk

(Note: %User Startup% is the current user's Startup folder, which is usually C:\Windows\Profiles\{user name}\Start Menu\Programs\Startup on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu\Programs\Startup on Windows NT, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup.)

Other System Modifications

This worm adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\iexplore
@ = "{true or fales} - {date of infection}"

Propagation

This worm drops the following copy(ies) of itself in all removable drives:

  • %Removable drive%\iexplore.vbs

Backdoor Routine

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

  • update - update and restart itself
  • uninstall - remove malware from system
  • send - download and run a file from C&C server
  • site-send - download and run a file
  • recv - send a file to C&C server
  • sleep - malware sleep

Download Routine

This worm accesses the following websites to download files:

  • dz47.{BLOCKED}e.com:225/is-sending
  • sexcam.{BLOCKED}es.com:225/is-sending

Information Theft

This worm gathers the following information on the affected computer:

  • Computer name
  • User name
  • Operating system version
  • Logical drives of serial numbers
  • Anti-virus products installed

Other Details

This worm connects to the following website to send and receive information:

  • dz47.{BLOCKED}e.com:225/is-ready
  • sexcam.{BLOCKED}es.com:225/is-ready

NOTES:

This malware connects to the following URLs to send a file:

  • dz47.{BLOCKEd}e.com:225 /is-recving
  • sexcam.{BLOCKED}ies.com:225 /is-recving

It sets the attributes of all dropped copies of itself to Hidden and System. It sets the attributes of all files and folders in removable drives to the aforementioned attributes as well. The malware then creates shortcuts with file names and icons same to the files and folders that were hidden. These shortcuts point to the dropped copy in the removable drive.

  SOLUTION

Minimum Scan Engine:

9.750

FIRST VSAPI PATTERN FILE:

11.504.06

FIRST VSAPI PATTERN DATE:

01 Feb 2015

VSAPI OPR PATTERN File:

11.505.00

VSAPI OPR PATTERN Date:

02 Feb 2015

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
    • iexplore = "wscript.exe //D "C:\Documents and Settings\winxp.KARLD-WINXP\Application Data\Internet Explorer\\iexplore.vbs""
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • iexplore = "wscript.exe //D "C:\Documents and Settings\winxp.KARLD-WINXP\Application Data\Internet Explorer\\iexplore.vbs""
  • In HKEY_LOCAL_MACHINE\SOFTWARE\iexplore
    • @ = "false - {date of infection}"

Step 5

Search and delete these files

[ 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.
  • %User Startup%\iexplore.lnk

Step 6

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