WORM_VESENLO.SOW

 Analysis by: Anthony Joe Melgarejo

 ALIASES:

Worm:Win32/Vesenlosow.A (Microsoft), W32.Virut.CF (Symantec), W32/Vesenlosow.worm (McAfee), W32/VB-FRE (Sophos), Worm.Vesenlosow (ClamAV), W32/VB.NZT!tr (Fortinet), Trojan.Win32.VB (Ikarus), Win32/VB.NZT worm (ESET), W32/Vobfus.GEP.worm (Panda), Trojan.Keylogger.1021 (VBA32)

 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: Worm

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet, Dropped by other malware, Propagates via flashdrives

This worm arrives by connecting affected removable drives to a system. It arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

As of this writing, the said sites are inaccessible.

It logs a user's keystrokes to steal information.

  TECHNICAL DETAILS

File Size:

880,640 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

15 Mar 2013

Payload:

Compromises system security, Connects to URLs/IPs, Steals information

Arrival Details

This worm arrives by connecting affected removable drives to a system.

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:

  • %User Profile%\Wins7\msmm.exe

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

It drops the following files:

  • %Start Menu%\Programs\Startups\desktop.ini - non-malicious file

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

It creates the following folders:

  • %User Profile%\Wins7
  • %User Profile%\Wins7\shin
  • %Start Menu%\Programs\Startups
  • %User Profile%\Wins7\shin0 - dropped upon certain conditions

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

Autostart Technique

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

  • %User Startup%\Sound Player.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\CurrentControlSet\services\
SharedAccess\Parameters\FirewallPolicy\
FirewallRules - Windows Vista and 7 only
{Random GUID} = "v{version number}|Action=Allow|Active=TRUE|Dir=In|Protocol=6|Profile=Private|App=%System\ftp.exe|Name=Windows%|"

HKEY_LOCAL_MACHINE\CurrentControlSet\services\
SharedAccess\Parameters\FirewallPolicy\
FirewallRules - Windows Vista and 7 only
{Random GUID 2} = "v{version number}|Action=Allow|Active=TRUE|Dir=In|Protocol=17|Profile=Private|App=%System\ftp.exe|Name=Windows%|"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List - Windows OS other than Vista and 7
%System%\ftp.exe = "%System%\ftp.exe:*:Enabled:Windows"

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\AppCompatFlags\
Layers
%System%\cmd.exe = "RUNASADMIN"

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\AppCompatFlags\
Layers
%User Profile%\Wins7\msmm,exe = "ELEVATECREATEPROCESS"

Propagation

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

  • {drive letter}:\New.exe

Dropping Routine

This worm drops the following files wherein it saves the information it gathers:

  • %User Profile%\Wins7\shin\sss.col - encrypted keylogs
  • %User Profile%\Wins7\shin0\sss.col - encrypted keylogs. dropped upon certain conditions

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

Download Routine

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

  • {BLOCKED}p.{BLOCKED}q.com

It saves the files it downloads using the following names:

  • %User Profile%\Wins7\bil.col

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

As of this writing, the said sites are inaccessible.

Information Theft

This worm logs a user's keystrokes to steal information.

Drop Points

This worm uploads files to the following File Transfer Protocol (FTP) sites:

  • ftp.drivehq.com

NOTES:

It monitors the following browser and instant messaging client:

  • Internet Explorer
  • Yahoo Messenger

It steals from the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion
Values: ProductName
CSDVersion

HKEY_LOCAL_MACHINE\HARDWARE\DESCRIPTION\System
Values: SystemBiosVersion

HKEY_LOCAL_MACHINE\HARDWARE\DESCRIPTION\System\CentralProcessor\0
Value: ProcessorNameString

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Cryptography
Value: MachineGUID

The conditions mentioned above are the following:

  • Date: May 10
  • Year: 2008 onwards
  • Time: 3:12 AM

Once the conditions are met, the malware will log the keystrokes to the newly dropped file and send the previously stolen information.

It attempts to check for the following analysis tools:

  • File Monitor
  • Process Monitor
  • Registry Monitor

  SOLUTION

Minimum Scan Engine:

9.300

FIRST VSAPI PATTERN FILE:

9.790.05

FIRST VSAPI PATTERN DATE:

15 Mar 2013

VSAPI OPR PATTERN File:

9.791.00

VSAPI OPR PATTERN Date:

15 Mar 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

Terminate a malware/grayware process

[ Learn More ]

*Note: If the detected process is not displayed in theWindows Task Manager, continue doing the next steps.

    • msmm.exe

Step 3

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\CurrentControlSet\services\SharedAccess\Parameters\FirewallPolicy\FirewallRules - Windows Vista and 7 only
    • {Random GUID} = "v{version number}|Action=Allow|Active=TRUE|Dir=In|Protocol=6|Profile=Private|App=%System\ftp.exe|Name=Windows%|"
  • In HKEY_LOCAL_MACHINE\CurrentControlSet\services\SharedAccess\Parameters\FirewallPolicy\FirewallRules - Windows Vista and 7 only
    • {Random GUID 2} = "v{version number}|Action=Allow|Active=TRUE|Dir=In|Protocol=17|Profile=Private|App=%System\ftp.exe|Name=Windows%|"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List - Windows OS other than Vista and 7
    • %System%\ftp.exe = "%System%\ftp.exe:*:Enabled:Windows"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\AppCompatFlags\Layers
    • %System%\cmd.exe = "RUNASADMIN"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\AppCompatFlags\Layers
    • %User Profile%\Wins7\msmm,exe = "ELEVATECREATEPROCESS"

Step 4

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.
  • %User Profile%\Wins7
  • %Start Menu%\Programs\Startups

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.
  • {drive letter}:\New.exe
  • %User Startup%\Sound Player.lnk

Step 6

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