TROJ_MDROPPR.FL

 Analysis by: Mark Joseph Manahan

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This Trojan arrives as an attachment to email messages spammed by other malware/grayware or malicious users. It may be manually installed by a user.

  TECHNICAL DETAILS

File Size:

2,591,077 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

01 Oct 2012

Arrival Details

This Trojan arrives as an attachment to email messages spammed by other malware/grayware or malicious users.

It may be manually installed by a user.

Installation

This Trojan adds the following folders:

  • %Program Files%\FlasshPlayer
  • %Program Files%\FlasshPlayer\Uninstall

(Note: %Program Files% is the default Program Files folder, usually C:\Program Files.)

It drops the following files:

  • %Application Data%\{Random Numbers 1}.exe
  • %Application Data%\{Random Numbers 2}.exe
  • %Application Data%\Microsoft\cssrss.exe
  • %Application Data%\RES.exe
  • %Program Files%\FlasshPlayer\Uninstall\IRIMG1.JPG
  • %Program Files%\FlasshPlayer\Uninstall\IRIMG2.JPG
  • %Program Files%\FlasshPlayer\Uninstall\uninstall.dat
  • %Program Files%\FlasshPlayer\Uninstall\uninstall.xml
  • %Program Files%\FlasshPlayer\lua5.1.dll
  • %Program Files%\FlasshPlayer\uninstall.exe
  • %User Startup%\lassa52.exe
  • %User Temp%\FlasshPlayer Setup Log.txt
  • %Windows%\bss.exe
  • %Windows%\lassa52.exe
  • %Windows%\livs.exe
  • %Windows%\reas.exe

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Windows\Profiles\{user name}\Application Data on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Application Data on Windows NT, and C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003.. %Program Files% is the default Program Files folder, usually C:\Program Files.. %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.. %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.. %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.)

Autostart Technique

This Trojan creates the following registry entries to enable automatic execution of dropped component at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
Key Name = "%Application Data%\Microsoft\cssrss.exe\Microsoft\cssrss.exe"

Other System Modifications

This Trojan adds the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
FlasshPlayer11.17.01

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://{BLOCKED}dreacharounds.info/umhttp/panel/bot.php

  SOLUTION

Minimum Scan Engine:

9.200

FIRST VSAPI PATTERN FILE:

9.436.04

FIRST VSAPI PATTERN DATE:

02 Oct 2012

VSAPI OPR PATTERN File:

9.437.00

VSAPI OPR PATTERN Date:

03 Oct 2012

Step 1

For Windows XP and Windows Server 2003 users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.

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.

  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall
    • FlasshPlayer11.17.01

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\Windows\CurrentVersion\Run
    • Key Name = "%Application Data%\Microsoft\cssrss.exe\Microsoft\cssrss.exe"

Step 5

Search and delete this folder

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.  
  • %Program Files%\FlasshPlayer

Step 6

Search and delete these files

[ Learn More ]
There may be some component 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%\{Random Numbers 1}.exe
  • %Application Data%\{Random Numbers 2}.exe
  • %Application Data%\Microsoft\cssrss.exe
  • %Application Data%\RES.exe
  • %User Startup%\lassa52.exe
  • %User Temp%\FlasshPlayer Setup Log.txt
  • %Windows%\bss.exe
  • %Windows%\lassa52.exe
  • %Windows%\livs.exe
  • %Windows%\reas.exe

Step 7

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