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TROJ_RANSOM.BNW
Aliases: Trojan:Win32/Reveton.A (Microsoft); Mal/ZboCheMan-A (Sophos)
Malware type: Trojan
Destructive: No
Platform: Windows 2000, Windows XP, Windows Server 2003
Encrypted: Yes
In the wild: Yes

Overview


This is a ransomware scam that pretends to be a threatening message from Scotland Yard but actually hijacks the user's computer and demands money to unlock it.

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

This Trojan executes another instance of explorer.exe where it injects itself. It then opens a notepad.exe process and injects its codes into it. The injected code in notepad.exe then disables the desktop of the affected user and open a browser window connecting to a certain site.

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

It modifies the Internet Explorer Zone Settings.

Technical Details


File size: Varies
File type: DLL
Memory resident: Yes
Initial samples received date: 14 Feb 2012
Payload: Disables desktop, Terminates processes, Connects to URLs/IPs

Arrival Details

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

Installation

This Trojan drops the following files:

  • %User Startup%\{malware filename}.lnk - autostart component

(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\Policies\
System
DisableTaskMgr = "1"

Process Termination

This Trojan terminates the following services if found on the affected system:

  • avp.exe

Web Browser Home Page and Search Page Modification

This Trojan modifies the Internet Explorer Zone Settings.

NOTES:

Upon execution, it executes another instance of explorer.exe where it injects itself. It then opens a notepad.exe process and injects its codes into it.

The injected code in notepad.exe then disables the desktop of the affected user and open a browser window connecting to the following site:

  • http://{BLOCKED}.{BLOCKED}.163.204/

The site asks a user to pay a certain amount of money in order to recover the disabled system.

As of this writing, the said site is inaccessible.

Solution


Minimum scan engine: 9.200
First VSAPI Pattern File: 8.778.01
First VSAPI Pattern Release Date: 15 Feb 2012
VSAPI OPR Pattern Version: 8.779.00
VSAPI OPR Pattern Release Date: 16 Feb 2012

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

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.
  • %User Startup%\{malware filename}.lnk

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\Policies\System
    • DisableTaskMgr = "1"

Step 5

Reset Internet security settings

[ Learn more ]

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_RANSOM.BNW. 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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Analysis By: Roland Marco Dela Paz

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