TROJ_LOCKRVTN.EA

February 02, 2015
 Analysis by: Francis Xavier Antazo
 ALIASES:

Ransom:Win32/Urausy.C (MICROSOFT), Trojan.Win32.Reveton.a (v) (SUNBELT)

 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet

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. However, as of this writing, the said sites are inaccessible.

  TECHNICAL DETAILS

File Size:

164,352 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

29 Jun 2013

Payload:

Locks PC screen, Connects to URLs/IPs

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.

However, as of this writing, the said sites are inaccessible.

Installation

This Trojan drops the following component file(s):

  • %Application Data%\skype.ini

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

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

  • %Application Data%\skype.dat

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\Winlogon
shell = "explorer.exe, "%Application Data%\skype.dat""

NOTES:

This Trojan locks the screen, disabling taskmgr.exe and explorer.exe) and displays a large window.

It attempts to download the lock screen message from the following URLs:

  • {domain 1}/{variable 1}/{long random characters}.{variable 2}
  • {domain 2}/{long random characters}.{variable 2}

Where {domain 1} may be any of the following:

  • {BLOCKED}mage.xxuz.com
  • {BLOCKED}ics.xxuz.com
  • {BLOCKED}itecreation.info
  • {BLOCKED}werpairs.biz
  • {BLOCKED}fulltouch.pw
  • {BLOCKED}dinregister.pw
  • {BLOCKED}image.xxuz.com
  • {BLOCKED}eel.biz
  • {BLOCKED}uresextranet.biz

Where {domain 2} may be any of the following:

  • {BLOCKED}e.net
  • {BLOCKED}s.com
  • {BLOCKED}i.su
  • {BLOCKED}i.su
  • {BLOCKED}i.com
  • {BLOCKED}w.com
  • {BLOCKED}r.net
  • {BLOCKED}k.ru
  • {BLOCKED}s.com
  • {BLOCKED}a.su
  • {BLOCKED}r.ru
  • {BLOCKED}d.ru
  • {BLOCKED}k.ru
  • {BLOCKED}u.ru
  • {BLOCKED}a.com

Where {variable 1} may be any of the following:

  • forum
  • community
  • news
  • forums
  • forum
  • mpgs
  • users
  • contact
  • article
  • manual

Where {variable 2} may be any of the following:

  • html
  • php

  SOLUTION

Minimum Scan Engine:

9.700

FIRST VSAPI PATTERN FILE:

11.442.04

FIRST VSAPI PATTERN DATE:

28 Jan 2015

VSAPI OPR PATTERN File:

11.443.00

VSAPI OPR PATTERN Date:

29 Jan 2015

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

Restart in Safe Mode

[ Learn More ]

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 NT\CurrentVersion\Winlogon
    • shell = "explorer.exe, "%Application Data%\skype.dat""

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.
  • %Application Data%\skype.ini

Step 6

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