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TROJ_RANSOM.BPA
Aliases: Trojan:Win32/Ransom.FL (Microsoft); Trojan.Ransomlock.G (Symantec)
Malware type: Trojan
Destructive: No
Platform: Windows 2000, Windows XP, Windows Server 2003
Encrypted: Yes
In the wild: Yes

Overview


Infection Channel: Downloaded from the Internet

Trend Micro has received multiple samples of this ransomware, particularly in EMEA region. These indicate that this ransomware poses a high risk to users due to the increased possibility of infection.

To get a one-glance comprehensive view of the behavior of this Trojan, refer to the Threat Diagram shown below.

Upon execution, this Trojan connects to a certain site to get the IP address, geographical location, city, and Internet Service Provider (ISP) of the affected system. It then blocks the desktop of the user and displays an image. It accuses the user of violating the laws of Belguim for several fabricated offenses. It then demands users to pay a fine via Ukash or Paysafecard voucher.

This Trojan may be unknowingly downloaded by a user while visiting malicious websites.

Technical Details


File size: 159,232 bytes
File type: EXE
Memory resident: Yes
Initial samples received date: 22 Feb 2012
Payload: Blocks user desktop

Arrival Details

This Trojan may be unknowingly downloaded by a user while visiting malicious websites.

Installation

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

  • %Windows%\explorer.exe
  • %System%\explorer.exe

(Note: %Windows% is the Windows folder, which is usually C:\Windows.. %System% is the Windows system folder, which is usually C:\Windows\System32.)

Process Termination

This Trojan terminates the following processes if found running in the affected system's memory:

  • taskmgr.exe
  • procexp.exe

NOTES:

Upon execution, it connects to the following site to get the IP address, geographical location, city, and Internet Service Provider (ISP) of the affected system:

  • http://{BLOCKED}ls.{BLOCKED}location.com/ib2/

It then blocks the desktop of the user and displays the following image:

The image above accuses the user of violating the laws of Belguim for several fabricated offenses. It then demands users to pay a fine via Ukash or Paysafecard voucher.

It reports system infection to the following site:

  • http://{BLOCKED}ohwxpnn.com/gate.php?cmd=ping&botnet={parameter}&userid={encoded user ID}&os={encoded operating system version}

Other Details

It saves the original explorer.exe file as follows:

  • %Windows%\twexx32.dll

Solution


Minimum scan engine: 9.200
First VSAPI Pattern File: 8.794.05
First VSAPI Pattern Release Date: 23 Feb 2012
VSAPI OPR Pattern Version: 8.795.00
VSAPI OPR Pattern Release Date: 23 Feb 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

Scan your computer with your Trend Micro product to delete files detected as TROJ_RANSOM.BPA. 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.

NOTES:

Do as Step 2:

To identify and delete the malware/grayware file:

  1. Insert your Windows Installation CD in your CD-rom.
  2. Press the restart button of your computer.
  3. When prompted, press any key to boot from the CD.
  4. When prompted on the Main Menu, type r to enter the recovery console.
    (Note: On Windows 2000, after pressing r, type c to choose the Recovery Console in the repair options screen.)
  5. When prompted, type your administrator password to log on.
  6. Once logged in, type the drive that contains Windows in the command prompt that appears, then press Enter.
  7. Type the following, then press Enter:

    del %Windows%\explorer.exe
    del %System%\explorer.exe
    copy %Windows%\twexx32.dll %Windows%\explorer.exe
    del %Windows%\twexx32.dll

  8. Type exit to restart the system normally.


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Analysis By: Roland Marco Dela Paz

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