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TROJ_UTOTI.TYZAL

March 06, 2014
 Analysis by: Alvin John Nieto
 ALIASES:

Trojan.Win32.Regrun.psv (Kaspersky), TR/Autoit.768727 (AntiVir), W32/Regrun.PSV!tr (Fortinet)

 PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet, Dropped by other malware


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 opens a hidden Internet Explorer window.

  TECHNICAL DETAILS

File Size:

Varies

File Type:

EXE

File Compression:

AutoIt

Memory Resident:

Yes

Initial Samples Received Date:

26 Feb 2014

Payload:

Terminates processes

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:

  • %System%\{Malware Name}

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
{Malware Name} = "%System%\{Malware} Name"

It modifies the following registry entries to ensure it automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Shell = "Explorer.exe %System%\{Malware Name}"

(Note: The default value data of the said registry entry is "Explorer.exe".)

Other System Modifications

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Policies\
System
EnableLUA = "0"

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

Process Termination

This Trojan terminates the following processes if found running in the affected system's memory:

  • avp.exe
  • wmiav.exe

Other Details

This Trojan connects to the following URL(s) to check for an Internet connection:

  • www.google.com

It opens a hidden Internet Explorer window.

It sets the attributes of the following file(s) to Hidden and System:

  • %System%\{Malware Name}

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)

NOTES:

This Trojan sets the system time to September 27, 2019, 09:04 AM. If there is an active Internet connection, it opens the browser to view the non-malicious URL http://site.com/index.php.

  SOLUTION

Minimum Scan Engine:

9.700

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 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\CurrentVersion\Run
    • {Malware Name} = "%System%\{Malware Name}"
  • In HKEY_LOCAL_MACHINE\Software\Microsft\Windows\CurrentVersion\Policies\System
    • EnableLua = "0"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • EnableBalloonTips = "0"

Step 4

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\Software\Microsoft\Windows NT\CurrentVersion\Winlogon
    • From: Shell = "Explorer.exe %System%\{Malware Name}"
      To: Shell = "Explorer.exe"

Step 5

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