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VBS_DUNIHI.PLAS

September 18, 2014
 Analysis by: Rika Joi Gregorio
 PLATFORM:

Windows

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW


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.

  TECHNICAL DETAILS

File Size:

118,656 bytes

File Type:

VBS

Memory Resident:

Yes

Initial Samples Received Date:

10 May 2014

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 and executes them:

  • %Application Data%\aiasfacoiaksf.vbs

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista and 7.)

It drops the following files:

  • {Drive}:\{folder / file name}.lnk

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
asodakaossd = "%System%\cmd.exe" /c start "%Application Data%\aiasfacoiaksf.vbs" exit"

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

  • %User Startup%\asodakaossd.lnk - points to %Application Data%\aiasfacoiaksf.vbs

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista and 7.)

Other System Modifications

This worm adds the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\aiasfacoiaksf

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\aiasfacoiaksf
(Default) = "{true or false} - {date of first execution}"

Propagation

This worm creates the following folders in all removable drives:

  • {Drive}:\ cfsdaacdfawd

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

  • {Drive}:\ cfsdaacdfawd\aiasfacoiaksf.vbss

Backdoor Routine

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

  • Execute file
  • Update itself
  • Uninstall itself
  • Download file
  • Upload file
  • Enumerate drives
  • Enumerate folders and files
  • Enumerate processes
  • Perform remote shell
  • Delete folders and files
  • Terminate itself
  • Sleep

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

  • {BLOCKED}m.no-ip.biz:81

Download Routine

This worm connects to the following URL(s) to download its configuration file:

  • http://{BLOCKED}ebin.com/raw.php?i=C27VjQAe (for x86 environment)
  • http://{BLOCKED}ebin.com/raw.php?i=hffzGc2s (for x64 environment)

It saves the files it downloads using the following names:

  • %Application Data%\{file name based on config file} - download routine based on configuration file

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista and 7.)

Information Theft

This worm s configuration file contains the following information:

  • Download link
  • Downloaded file name

It gathers the following data:

  • OS version
  • Computer name
  • User name
  • AV software installed
  • Volume information

NOTES:

This worm creates .LNK (shortcut) files using folder/file names found in removable drives. It then hides the original folder/file tricking users to click .LNK files. This .LNK files point out to a dropped copy of itself in the removable drive.

  SOLUTION

Minimum Scan Engine:

9.700

FIRST VSAPI PATTERN FILE:

11.152.05

FIRST VSAPI PATTERN DATE:

16 Sep 2014

VSAPI OPR PATTERN File:

11.153.00

VSAPI OPR PATTERN Date:

17 Sep 2014

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 key

[ 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
    • aiasfacoiaksf

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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • asodakaossd = "%System%\cmd.exe" /c start "%Application Data%\aiasfacoiaksf.vbs" exit"

Step 6

Search and delete these folders

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
  • {Drive}:\ cfsdaacdfawd

Step 7

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.
  • {Drive}:\{folder / file name}.lnk

Step 8

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