Analysis by: Arvin Roi Macaraeg
ALIASES:

Trojan:Win32/Lethic.I (MICROSOFT), HEUR:Trojan.Win32.Generic (KASPERSKY)

 PLATFORM:

Windows

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 SYSTEM IMPACT RATING:
 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.

  TECHNICAL DETAILS

File Size: 1,441,792 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 10 Feb 2011

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 and executes them:

  • %Application Data%\vfbu.exe

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, and 8.)

It drops the following files:

  • %User Temp%\{Random Character}.TMP

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, and 8.)

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Taskman = "%Application Data%\vfbu.exe"

Other System Modifications

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
RFC1156Agent\CurrentVersion\Parameters
TrapPollTimeMilliSecs = "15000"

HKEY_CURRENT_USER\Software\Licenses
{K7C0DB872A3F777C0} = {Hex Values}

HKEY_CURRENT_USER\Software\Licenses
{IAA4A1823DF778B97} = "01 00 00 00 "

HKEY_CURRENT_USER\Software\Licenses
{IAA4A1823DF778B97} = "02 00 00 00"

HKEY_CURRENT_USER\Software\Licenses
{IAA4A1823DF778B97} = "03 00 00 00"

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 14.528.03
FIRST VSAPI PATTERN DATE: 26 Sep 2018
VSAPI OPR PATTERN File: 14.529.00
VSAPI OPR PATTERN Date: 27 Sep 2018

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

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\RFC1156Agent\CurrentVersion\Parameters
    • TrapPollTimeMilliSecs = "15000"
  • In HKEY_CURRENT_USER\Software\Licenses
    • {K7C0DB872A3F777C0} = {Hex Values}
  • In HKEY_CURRENT_USER\Software\Licenses
    • {IAA4A1823DF778B97} = "01 00 00 00"
  • In HKEY_CURRENT_USER\Software\Licenses
    • {IAA4A1823DF778B97} = "02 00 00 00"
  • In HKEY_CURRENT_USER\Software\Licenses
    • {IAA4A1823DF778B97} = "03 00 00 00"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
    • Taskman = "%Application Data%\vfbu.exe"

Step 4

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.  
  • %Application Data%\vfbu.exe
  • %User Temp%\{Random Character}.TMP

Step 5

Scan your computer with your Trend Micro product to delete files detected as TROJAN.WIN32.LETHIC.AA. 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 the following Trend Micro Support pages for more information:


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