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TROJ_KILLAV.WUNX

April 11, 2014
 ALIASES:

RiskTool.Win32.Deleter.i (Kaspersky); Mal/Bancos-CO (Sophos); Trojan.Win32.Generic!BT (Sunbelt); Trojan horse KillAV.CXZ (AVG)

 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:

1,403,904 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

11 Apr 2014

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.

Other System Modifications

This Trojan adds the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center\Svc

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\Windows Defender

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\MRT

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Associations

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Attachments

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center
UACDisableNotify = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center
AutoUpdateDisableNotify = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center
InternetSettingsDisableNotify = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center
UpdatesOverride = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center\Svc
UACDisableNotify = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center\Svc
AntiVirusDisableNotify = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center\Svc
FirewallDisableNotify = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center\Svc
AntiVirusOverride = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center\Svc
FirewallOverride = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center\Svc
UpdatesDisableNotify = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center\Svc
UpdatesOverride = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\Windows Defender
DisableAntiSpyware = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\MRT
DontReportInfectionInformation = "1"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Associations
LowRiskFileTypes = ".exe;.bat;.com;.cmd;"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Attachments
SaveZoneInformation = "1"

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Download
RunInvalidSignatures = "1"

It modifies the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center
FirstRunDisabled = "1"

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center
AntiVirusDisableNotify = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center
AntiVirusOverride = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center
FirewallDisableNotify = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center
FirewallOverride = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center
UpdatesDisableNotify = "1"

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
HideFileExt = "1"

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

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Download
CheckExeSignatures = "no"

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

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

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\Microsoft\Security Center
    • Svc
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft
    • Windows Defender
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft
    • MRT
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies
    • Associations
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies
    • Attachments

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\SOFTWARE\Microsoft\Security Center
    • UACDisableNotify = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Security Center
    • AutoUpdateDisableNotify = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Security Center
    • InternetSettingsDisableNotify = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Security Center
    • UpdatesOverride = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Security Center\Svc
    • UACDisableNotify = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Security Center\Svc
    • AntiVirusDisableNotify = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Security Center\Svc
    • FirewallDisableNotify = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Security Center\Svc
    • AntiVirusOverride = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Security Center\Svc
    • FirewallOverride = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Security Center\Svc
    • UpdatesDisableNotify = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Security Center\Svc
    • UpdatesOverride = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender
    • DisableAntiSpyware = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\MRT
    • DontReportInfectionInformation = "1"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Associations
    • LowRiskFileTypes = ".exe;.bat;.com;.cmd;"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Attachments
    • SaveZoneInformation = "1"
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Download
    • RunInvalidSignatures = "1"

Step 4

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Security Center
    • From: FirstRunDisabled = "1"
      To: FirstRunDisabled = ""1""
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Security Center
    • AntiVirusDisableNotify = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Security Center
    • AntiVirusOverride = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Security Center
    • FirewallDisableNotify = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Security Center
    • FirewallOverride = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Security Center
    • UpdatesDisableNotify = "1"
  • 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
    • From: HideFileExt = "1"
      To: HideFileExt = ""1""
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Download
    • From: CheckExeSignatures = "no"
      To: CheckExeSignatures = ""yes""

Step 5

Scan your computer with your Trend Micro product to delete files detected as TROJ_KILLAV.WUNX. 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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