Analysis by: Erika Bianca Mendoza
 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  TECHNICAL DETAILS

File Size: 29184 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 10 Mar 2011
Payload: Drops files

Installation

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

  • %System%\userini.exe

(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)

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\Policies\
Explorer\Run
userini = "%System%\userini.exe"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
userini = "%System%\userini.exe"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
userini = "%System%\userini.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\policies\
Explorer\Run
userini = "%System%\userini.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
userini = "%System%\userini.exe"

Other System Modifications

This Trojan adds the following registry entries as part of its installation routine:

HKEY_CURRENT_USER\Software\Microsoft\
CTF
remove = "{malware path and file name}"

HKEY_CURRENT_USER\Software\Microsoft\
CTF
id = "20A5AFB8BF2A"

  SOLUTION

Minimum Scan Engine: 8.900

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

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\Policies\Explorer\Run
    • userini = %System%\userini.exe
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • userini = %System%\userini.exe
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • userini = %System%\userini.exe
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\Explorer\Run
    • userini = %System%\userini.exe
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • userini = %System%\userini.exe
  • In HKEY_CURRENT_USER\Software\Microsoft\CTF
    • remove = {malware path and file name}
  • In HKEY_CURRENT_USER\Software\Microsoft\CTF
    • id = 20A5AFB8BF2A

Step 3

Scan your computer with your Trend Micro product to delete files detected as TROJ_KRAP.ZVA. 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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