ALIASES:

Virus:Win32/Virut.gen!B (Microsoft); W32/Virut.gen (McAfee); W32.Virut!gen (Symantec); Virus.Win32.Virut.n (Kaspersky); Worm.Win32.Autorun.eeoa (v) (Sunbelt); Win32/Virut.Y (AVG)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

 OVERALL RISK RATING:
 REPORTED INFECTION:

  • Threat Type: File infector

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This file infector 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: 42,496 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 28 Jul 2013

Arrival Details

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

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
tnssb = "%System Root%\{malware file name}.exe"

Other System Modifications

This file infector adds the following registry keys:

HKEY_CURRENT_USER\Software\tnsbinstalled

It adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
WarnonBadCertRecving = "0"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
CertificateRevocation = "0"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
WarnonZoneCrossing = "0"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
WarnOnPostRedirect = "0"

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

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
Use FormSuggest = "yes"

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
DisableScriptDebuggerIE = "yes"

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
Error Dlg Displayed On Every Error = "no"

HKEY_CURRENT_USER\Software\tnsbinstalled
tnsbinstalled = "tnsbinstalled"

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_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
SuperHidden = "1"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
Zones\3
1601 = "0"

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

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
Disable Script Debugger = "yes"

(Note: The default value data of the said registry entry is no.)

Other Details

This file infector connects to the following possibly malicious URL:

  • http://lyj.{BLOCKED}aily.com:88/p6.asp?{random characters}

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine: 9.300

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_CURRENT_USER\Software
    • tnsbinstalled

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
    • tnssb = "%System Root%\{malware file name}.exe"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
    • WarnonBadCertRecving = "0"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
    • CertificateRevocation = "0"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
    • WarnonZoneCrossing = "0"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
    • WarnOnPostRedirect = "0"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • ShowSuperHidden = "0"
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
    • Use FormSuggest = "yes"
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
    • DisableScriptDebuggerIE = "yes"
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
    • Error Dlg Displayed On Every Error = "no"
  • In HKEY_CURRENT_USER\Software\tnsbinstalled
    • tnsbinstalled = "tnsbinstalled"

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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • SuperHidden = "1"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\3
    • From: 1601 = "0"
      To: 1601 = ""1""
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
    • From: Disable Script Debugger = "yes"
      To: Disable Script Debugger = ""no""

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as PE_VIRUT.XB-1. 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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