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TROJ_DLOADER.USL15VC

October 13, 2012
 ALIASES:

Rogue:Win32/FakeRean (Microsoft); FakeAlert-Rena.bh (McAfee); WindowsAVPro!gen1 (Symantec); Trojan.Win32.FakeAV.ixoe (Kaspersky); Trojan.Win32.Rena.bc (v) (Sunbelt); Gen:Variant.Kazy.46372 (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.

It modifies files, disabling programs and applications from properly running.

It deletes itself after execution.

  TECHNICAL DETAILS

File Size:

296,960 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

29 Jun 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.

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
340542829 = "%Application Data%\vke.exe"

Other System Modifications

This Trojan modifies the following files:

  • %Application Data%\GDIPFONTCACHEV1.DAT

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Windows\Profiles\{user name}\Application Data on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Application Data on Windows NT, and C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003.)

It adds the following registry keys:

HKEY_CURRENT_USER\.exe

HKEY_CURRENT_USER\.exe\DefaultIcon

HKEY_CURRENT_USER\.exe\shell

HKEY_CURRENT_USER\.exe\shell\
open

HKEY_CURRENT_USER\.exe\shell\
open\command

HKEY_CURRENT_USER\.exe\shell\
runas

HKEY_CURRENT_USER\.exe\shell\
runas\command

HKEY_CURRENT_USER\exefile

HKEY_CURRENT_USER\exefile\DefaultIcon

HKEY_CURRENT_USER\exefile\shell

HKEY_CURRENT_USER\exefile\shell\
open

HKEY_CURRENT_USER\exefile\shell\
open\command

HKEY_CURRENT_USER\exefile\shell\
runas

HKEY_CURRENT_USER\exefile\shell\
runas\command

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile
EnableFirewall = "0"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile
DoNotAllowExceptions = "0"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile
DisableNotifications = "1"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\SharedAccess\Parameters\
FirewallPolicy\DomainProfile
EnableFirewall = "0"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\SharedAccess\Parameters\
FirewallPolicy\DomainProfile
DoNotAllowExceptions = "0"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\SharedAccess\Parameters\
FirewallPolicy\DomainProfile
DisableNotifications = "1"

HKEY_CURRENT_USER\.exe
Content Type = "application/x-msdownload"

HKEY_CURRENT_USER\.exe\shell\
open\command
IsolatedCommand = "%1 %*"

HKEY_CURRENT_USER\.exe\shell\
runas\command
IsolatedCommand = "%1 %*"

HKEY_CURRENT_USER\exefile
Content Type = "application/x-msdownload"

HKEY_CURRENT_USER\exefile\shell\
open\command
IsolatedCommand = "%1 %*"

HKEY_CURRENT_USER\exefile\shell\
runas\command
IsolatedCommand = "%1 %*"

HKEY_CURRENT_USER\Software\Microsoft\
Windows
Identity = "42d18fbc"

It modifies the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\SharedAccess
Start = "4"

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

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\Run
ctfmon.exe = "%System%\ctfmon.exe"

(Note: The default value data of the said registry entry is %Windows%\system32\ctfmon.exe.)

HKEY_CURRENT_USER\Software\Microsoft\
GDIPlus
FontCachePath = "%Application Data%"

(Note: The default value data of the said registry entry is %User Profile%\Local Settings\Application Data.)

Dropping Routine

This Trojan drops the following files:

  • %User Temp%\anb1.tmp
  • %User Temp%\anb2.tmp
  • %Application Data%\vke.exe
  • %User Temp%\anb3.tmp
  • %User Temp%\anb4.tmp

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003.. %Application Data% is the current user's Application Data folder, which is usually C:\Windows\Profiles\{user name}\Application Data on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Application Data on Windows NT, and C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003.)

Other Details

This Trojan deletes itself after execution.

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.200

Step 1

For Windows XP and Windows Server 2003 users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.

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
    • .exe
  • In HKEY_CURRENT_USER\.exe
    • DefaultIcon
  • In HKEY_CURRENT_USER\.exe
    • shell
  • In HKEY_CURRENT_USER\.exe\shell
    • open
  • In HKEY_CURRENT_USER\.exe\shell\open
    • command
  • In HKEY_CURRENT_USER\.exe\shell
    • runas
  • In HKEY_CURRENT_USER\.exe\shell\runas
    • command
  • In HKEY_CURRENT_USER
    • exefile
  • In HKEY_CURRENT_USER\exefile
    • DefaultIcon
  • In HKEY_CURRENT_USER\exefile
    • shell
  • In HKEY_CURRENT_USER\exefile\shell
    • open
  • In HKEY_CURRENT_USER\exefile\shell\open
    • command
  • In HKEY_CURRENT_USER\exefile\shell
    • runas
  • In HKEY_CURRENT_USER\exefile\shell\runas
    • command

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
    • 340542829 = "%Application Data%\vke.exe"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile
    • EnableFirewall = "0"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile
    • DoNotAllowExceptions = "0"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile
    • DisableNotifications = "1"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\SharedAccess\Parameters\FirewallPolicy\DomainProfile
    • EnableFirewall = "0"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\SharedAccess\Parameters\FirewallPolicy\DomainProfile
    • DoNotAllowExceptions = "0"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\SharedAccess\Parameters\FirewallPolicy\DomainProfile
    • DisableNotifications = "1"
  • In HKEY_CURRENT_USER\.exe
    • Content Type = "application/x-msdownload"
  • In HKEY_CURRENT_USER\.exe\shell\open\command
    • IsolatedCommand = "%1 %*"
  • In HKEY_CURRENT_USER\.exe\shell\runas\command
    • IsolatedCommand = "%1 %*"
  • In HKEY_CURRENT_USER\exefile
    • Content Type = "application/x-msdownload"
  • In HKEY_CURRENT_USER\exefile\shell\open\command
    • IsolatedCommand = "%1 %*"
  • In HKEY_CURRENT_USER\exefile\shell\runas\command
    • IsolatedCommand = "%1 %*"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows
    • Identity = "42d18fbc"

Step 5

Restore this modified 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\SYSTEM\ControlSet001\Services\SharedAccess
    • From: Start = "4"
      To: Start = ""2""
  • 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\Run
    • From: ctfmon.exe = "%System%\ctfmon.exe"
      To: ctfmon.exe = ""%Windows%\system32\ctfmon.exe""
  • In HKEY_CURRENT_USER\Software\Microsoft\GDIPlus
    • From: FontCachePath = "%Application Data%"
      To: FontCachePath = ""%User Profile%\Local Settings\Application Data""

Step 6

Search and delete these files

[ Learn More ]
There may be some component 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.
  • %User Temp%\anb1.tmp
  • %User Temp%\anb2.tmp
  • %Application Data%\vke.exe
  • %User Temp%\anb3.tmp
  • %User Temp%\anb4.tmp

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_DLOADER.USL15VC. 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 8

Restore deleted/modified files and/or registry entries from backup

*Note: Only Microsoft-related files/keys/values will be restored. If this malware/grayware also deleted registry keys/values related to programs that are not from Microsoft, please reinstall those programs on your computer.

    • %Application Data%\GDIPFONTCACHEV1.DAT


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