ALIASES:

Trojan:Win32/Netvat.A!dll, Trojan:Win32/Netvat.A!dll (Microsoft); [000024f0.EXE]:Generic.dx!bcm4 (McAfee); W32.Stration@mm (Symantec); Trojan.Win32.Agent.cyzi (Kaspersky); Trojan.Win32.Generic.pak!cobra (Sunbelt); Dropped:Trojan.Generic.IS.433864 (FSecure)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

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

  TECHNICAL DETAILS

File Size: 63,488 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 29 Apr 2012

Arrival Details

This Trojan 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 Trojan drops the following copies of itself into the affected system:

  • %Program Files%\360rpv.exe

(Note: %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000, Server 2003, and XP (32-bit), Vista (32-bit), and 7 (32-bit), or C:\Program Files (x86) in Windows XP (64-bit), Vista (64-bit), and 7 (64-bit).)

It creates the following folders:

  • %Program Files%\Common Files\Plugins

(Note: %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000, Server 2003, and XP (32-bit), Vista (32-bit), and 7 (32-bit), or C:\Program Files (x86) in Windows XP (64-bit), Vista (64-bit), and 7 (64-bit).)

Autostart Technique

This Trojan registers as a system service to ensure its automatic execution at every system startup by adding the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Avt-Net\Parameters

Other System Modifications

This Trojan deletes the following files:

  • %Program Files%\Common Files\Plugins\index.txt

(Note: %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000, Server 2003, and XP (32-bit), Vista (32-bit), and 7 (32-bit), or C:\Program Files (x86) in Windows XP (64-bit), Vista (64-bit), and 7 (64-bit).)

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\SvcHost
Avt-Net = "Avt-Net"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Avt-Net
Description = "{random characters}"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Avt-Net
DisplayName = "Portable Sound Serial Number Services"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Avt-Net
ErrorControl = "1"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Avt-Net
Group = "Com Infrastructure"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Avt-Net
ObjectName = "LocalSystem"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Avt-Net
Start = "2"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Avt-Net
Type = "1"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Avt-Net
FailureAction = "{random values}"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Avt-Net
ImagePath = "%SystemRoot%\system32\svchost -k Avt-Net"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Avt-Net\Parameters
ServiceDll = "%SystemRoot%\system32\svcnet32.dll"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
exefile
NeverShowExt = "0"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
ShowSuperHidden = "0"

It modifies the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
Hidden = "2"

(Note: The default value data of the said registry entry is 2.)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced\Folder\Hidden\
SHOWALL
CheckedValue = "0x00000001 (1)"

(Note: The default value data of the said registry entry is 1.)

Dropping Routine

This Trojan drops the following files:

  • %System%\svcnet32.dll
  • %Program Files%\syslass.cpl

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.. %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000, Server 2003, and XP (32-bit), Vista (32-bit), and 7 (32-bit), or C:\Program Files (x86) in Windows XP (64-bit), Vista (64-bit), and 7 (64-bit).)

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://messager.{BLOCKED}p.net:99/index.txt

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine: 9.200

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

Restart in Safe Mode

[ Learn More ]

Step 3

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\SYSTEM\CurrentControlSet\Services\Avt-Net
    • Parameters

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SvcHost
    • Avt-Net = "Avt-Net"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Avt-Net
    • Description = "{random characters}"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Avt-Net
    • DisplayName = "Portable Sound Serial Number Services"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Avt-Net
    • ErrorControl = "1"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Avt-Net
    • Group = "Com Infrastructure"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Avt-Net
    • ObjectName = "LocalSystem"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Avt-Net
    • Start = "2"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Avt-Net
    • Type = "1"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Avt-Net
    • FailureAction = "{random values}"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Avt-Net
    • ImagePath = "%SystemRoot%\system32\svchost -k Avt-Net"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Avt-Net\Parameters
    • ServiceDll = "%SystemRoot%\system32\svcnet32.dll"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\exefile
    • NeverShowExt = "0"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • ShowSuperHidden = "0"

Step 5

Restore these modified registry values

[ Learn More ]

Important:Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator's help. You may also check out this Microsoft article first before modifying your computer's registry.

  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • From: Hidden = "2"
      To: Hidden = ""2""
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Advanced\Folder\Hidden\SHOWALL
    • From: CheckedValue = "0x00000001 (1)"
      To: CheckedValue = ""1""

Step 6

Search and delete these components

[ Learn More ]
There may be some components 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.
  • %System%\svcnet32.dll
  • %Program Files%\syslass.cpl

Step 7

Search and delete this folder

[ 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.
  • %Program Files%\Common Files\Plugins

Step 8

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

Step 9

Restore this file from backup only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on you computer again.

  • %Program Files%\Common Files\Plugins\index.txt


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