TROJ_REVETON.YH

 Analysis by: Nikko Tamana

 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


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 Internet Explorer security settings. This puts the affected computer at greater risk, as it allows malicious URLs to be accessed by the computer.

  TECHNICAL DETAILS

File Size:

131,072 bytes

File Type:

DLL

Memory Resident:

Yes

Initial Samples Received Date:

05 Aug 2013

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 file(s)/component(s):

  • {Malware Path}\{random file name 1}.txt
  • {Malware Path}\{random file name 2}.txt
  • {Malware Path}\{random file name}.js
  • {Malware Path}\{random file name}.pad
  • {Malware Path}\rundll32.exe
  • %System Root%\Users\All Users\{random file name 1}.txt - Windows Vista or 7
  • %System Root%\Users\All Users\{random file name 2}.txt - Windows Vista or 7
  • %System Root%\Users\All Users\{random file name}.js - Windows Vista or 7
  • %System Root%\Users\All Users\{random file name}.pad - Windows Vista or 7
  • %System Root%\Users\All Users\rundll32.exe - Windows Vista or 7

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

It drops the following copies of itself into the affected system:

  • {Malware Path}\{randomfile name}.dat
  • %System Root%\Users\All Users\{randomfile name}.dat - Windows Vista or 7

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

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
ctfmon32.exe = "{Malware Path}\rundll32.exe {Malware Path}\{random file name}.dat,XFG00"

It drops the following file(s) in the Windows User Startup folder to enable its automatic execution at every system startup:

  • %User Startup%\regmonstd.lnk

(Note: %User Startup% is the current user's Startup folder, which is usually C:\Windows\Profiles\{user name}\Start Menu\Programs\Startup on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu\Programs\Startup on Windows NT, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup.)

Other System Modifications

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

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
NoProtectedModeBanner = "1"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
Zones\0
2500 = "3"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
Zones\1
2500 = "3"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
Zones\2
2500 = "3"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
Zones\3
2500 = "3"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
Zones\4
2500 = "3"

It adds the following registry keys as part of its installation routine:

HKEY_CURRENT_USER\Software\Live Security Professional

Web Browser Home Page and Search Page Modification

This Trojan modifies Internet Explorer zone settings.

Other Details

This Trojan connects to the following possibly malicious URL:

  • https://{BLOCKED}.{BLOCKED}.53.169
  • https://{BLOCKED}.{BLOCKED}.122.10

  SOLUTION

Minimum Scan Engine:

9.300

FIRST VSAPI PATTERN FILE:

10.198.03

FIRST VSAPI PATTERN DATE:

05 Aug 2013

VSAPI OPR PATTERN File:

10.199.00

VSAPI OPR PATTERN Date:

06 Aug 2013

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 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_CURRENT_USER\Software
    • Live Security Professional

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\Internet Explorer\Main
    • NoProtectedModeBanner = "1"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\0
    • 2500 = "3"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\1
    • 2500 = "3"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\2
    • 2500 = "3"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\3
    • 2500 = "3"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\4
    • 2500 = "3"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • ctfmon32.exe = "{Malware Path}\rundll32.exe {Malware Path}\{random file name}.dat,XFG00"

Step 5

Search and delete this file

[ 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.
  • {Malware Path}\{random file name 1}.txt
  • {Malware Path}\{random file name 2}.txt
  • {Malware Path}\{random file name}.js
  • {Malware Path}\{random file name}.pad
  • {Malware Path}\rundll32.exe
  • %System Root%\Users\All Users\{random file name 1}.txt - Windows Vista or 7
  • %System Root%\Users\All Users\{random file name 2}.txt - Windows Vista or 7
  • %System Root%\Users\All Users\{random file name}.js - Windows Vista or 7
  • %System Root%\Users\All Users\{random file name}.pad - Windows Vista or 7
  • %System Root%\Users\All Users\rundll32.exe - Windows Vista or 7
  • %User Startup%\regmonstd.lnk
  • {Malware Path}\{randomfile name}.dat
  • %System Root%\Users\All Users\{randomfile name}.dat - Windows Vista or 7

Step 6

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