TROJ_KOVTER.DZD


 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This Trojan may be downloaded from remote sites by other malware.

It modifies the Internet Explorer Zone Settings.

It deletes the initially executed copy of itself.

  TECHNICAL DETAILS

File Size:

323,754 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

23 Dec 2016

Arrival Details

This Trojan may be downloaded from remote site(s) by the following malware:

Installation

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

  • %AppDataLocal%\{random string}\{random string}.exe

(Note: %AppDataLocal% is the Application Data folder found in Local Settings, where it is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

It drops the following files:

  • %AppDataLocal%\{random foldername}\{random filename}.bat - starts Encrypted file
  • %AppDataLocal%\{random foldername}\{random filename}.{random extension} - Encrypted file

(Note: %AppDataLocal% is the Application Data folder found in Local Settings, where it is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

It adds the following processes:

  • regsvr32.exe

It creates the following folders:

  • %AppDataLocal%\{random foldername}

(Note: %AppDataLocal% is the Application Data folder found in Local Settings, where it is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

It injects codes into the following process(es):

  • created regsvr32.exe

Autostart Technique

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

HKEY_CURRENT_USER\Software\Classes\
{random key 2}\shell\open\
command
(Default) = ""%System%\mshta.exe" javascript:{random}="{random}";{variable 1}=new%20ActiveXObject("WScript.Shell");{random}="{random}";{variable 2}={variable 1}.RegRead("HKCU\software\{random key 1}\{random valuename 2}");{random}="{random}";eval({variable 2});{random}="{random}";"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
(Default) = ""%System%\mshta.exe" javascript:{random}="{random}";{variable 1}=new%20ActiveXObject("WScript.Shell");{random}="{random}";{variable 2}={variable 1}.RegRead("HKCU\software\{random key 1}\{random valuename 2}");{random}="{random}";eval({variable 2});{random}="{random}";"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
(Default) = ""%System%\mshta.exe" javascript:{random}="{random}";{variable 1}=new%20ActiveXObject("WScript.Shell");{random}="{random}";{variable 2}={variable 1}.RegRead("HKLM\software\{random key 1}\{random valuename 2}");{random}="{random}";eval({variable 2});{random}="{random}";"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
(Default) = %AppDataLocal%\{random string}\{random string}.exe"

Other System Modifications

This Trojan adds the following registry keys:

HKEY_CURRENT_USER\Software\{random key 1}

HKEY_LOCAL_MACHINE\SOFTWARE\{random key 1}

HKEY_CURRENT_USER\Software\Classes\
.{random extension}

HKEY_CURRENT_USER\Software\Classes\
{random key 2}

It adds the following registry entries:

HKEY_CURRENT_USER\Software\{random key 1}
{random valuename 1} = "{Encrypted Data}"

HKEY_CURRENT_USER\Software\{random key 1}
{random valuename 2} = "{Loader Script}"

HKEY_CURRENT_USER\Software\{random key 1}
{random valuename 3} = "{User-Agent}"

HKEY_CURRENT_USER\Software\{random key 1}
{random valuename 4} = "{3 random number}"

HKEY_CURRENT_USER\Software\{random key 1}
{random valuename 5} = "{16 hex numbers}"

HKEY_CURRENT_USER\Software\{random key 1}
{random valuename 6} = "{10 random numbers}"

HKEY_LOCAL_MACHINE\SOFTWARE\{random key 1}
{random valuename 1} = "{Encrypted Data}"

HKEY_LOCAL_MACHINE\SOFTWARE\{random key 1}
{random valuename 2} = "{Loader Script}"

HKEY_LOCAL_MACHINE\SOFTWARE\{random key 1}
{random valuename 3} = "{User-Agent}"

HKEY_LOCAL_MACHINE\SOFTWARE\{random key 1}
{random valuename 4} = "{3 random number}"

HKEY_LOCAL_MACHINE\SOFTWARE\{random key 1}
{random valuename 5} = "{16 hex numbers}"

HKEY_LOCAL_MACHINE\SOFTWARE\{random key 1}
{random valuename 6} = "{10 random numbers}"

Web Browser Home Page and Search Page Modification

This Trojan modifies the Internet Explorer Zone Settings.

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://{BLOCKED}.{BLOCKED}.72.90/upload.php
  • {random generated ip address} → used for click-fraud activity

It deletes the initially executed copy of itself

  SOLUTION

Minimum Scan Engine:

9.800

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

Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.

Step 3

Restart in Safe Mode

[ Learn More ]

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\Classes\{random key 2}\shell\open\command
    • (Default) = ""%System%\mshta.exe" javascript:{random}="{random}";{variable 1}=new%20ActiveXObject("WScript.Shell");{random}="{random}";{variable 2}={variable 1}.RegRead("HKCU\software\{random key 1}\{random valuename 2}");{random}="{random}";eval({variable 2});{random}="{random}";"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • (Default) = ""%System%\mshta.exe" javascript:{random}="{random}";{variable 1}=new%20ActiveXObject("WScript.Shell");{random}="{random}";{variable 2}={variable 1}.RegRead("HKCU\software\{random key 1}\{random valuename 2}");{random}="{random}";eval({variable 2});{random}="{random}";"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • (Default) = ""%System%\mshta.exe" javascript:{random}="{random}";{variable 1}=new%20ActiveXObject("WScript.Shell");{random}="{random}";{variable 2}={variable 1}.RegRead("HKLM\software\{random key 1}\{random valuename 2}");{random}="{random}";eval({variable 2});{random}="{random}";"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • (Default) = %AppDataLocal%\{random string}\{random string}.exe"

Step 5

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
    • {random key 1}
  • In HKEY_LOCAL_MACHINE\SOFTWARE
    • {random key 1}
  • In HKEY_CURRENT_USER\Software\Classes
    • .{random extension}
  • In HKEY_CURRENT_USER\Software\Classes
    • {random key 2}

Step 6

Search and delete these files

[ Learn More ]
There may be some 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.
  • %AppDataLocal%\{random foldername}\{random filename}.bat
  • %AppDataLocal%\{random foldername}\{random filename}.{random extension}

Step 7

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