TROJ_RANSOM.ERA

January 27, 2014
 Modified by: Anthony Joe Melgarejo
 ALIASES:

Trojan:Win32/Ransom.FO (Microsoft), W32/Xorist.ER!tr (Fortinet), a variant of Win32/Filecoder.Q trojan (ESET)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: No

  • 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:

13,312 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

25 Jan 2014

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:

  • %User Temp%\hfqKbCfdb5R9xA9.exe

(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 and 7.)

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
Alcmeter = "%User Temp%\hfqKbCfdb5R9xA9.exe"

Other System Modifications

This Trojan adds the following registry keys:

HKEY_CLASSES_ROOT\.LOCKED

HKEY_CLASSES_ROOT\TMDCHXKKVCVJWNI

HKEY_CLASSES_ROOT\Applications\hfqKbCfdb5R9xA9.exe

It adds the following registry entries:

HKEY_CLASSES_ROOT\TMDCHXKKVCVJWNI\DefaultIcon
(Default) = "%User Temp%\hfqKbCfdb5R9xA9.exe,0"

HKEY_CLASSES_ROOT\TMDCHXKKVCVJWNI
(Default) = "LOCKED"

Other Details

This Trojan encrypts files with the following extensions:

  • .zip
  • .rar
  • .7z
  • .tar
  • .gzip
  • .jpg
  • .jpeg
  • .tif
  • .psd
  • .cdr
  • .dwg
  • .max
  • .bmp
  • .gif
  • .png
  • .doc
  • .docx
  • .xls
  • .xlsx
  • .ppt
  • .pptx
  • .txt
  • .pdf
  • .djvu
  • .htm
  • .html
  • .mdb
  • .cer
  • .p12
  • .pfx
  • .kwm
  • .pwm
  • .1cd
  • .md
  • .mdf
  • .dbf
  • .odt
  • .vob
  • .iso
  • .ifo
  • .csv
  • .torrent
  • .mov
  • .m2v
  • .3gp
  • .mpeg
  • .mpg
  • .flv
  • .avi
  • .mp4
  • .wmv
  • .divx
  • .mkv
  • .mp3
  • .wav
  • .flac
  • .ape
  • .wma
  • .ac3
  • .epub
  • .eps
  • .ai
  • .pps
  • .pptm
  • .accdb
  • .pst
  • .dwg
  • .dxf
  • .dxg
  • .wpd
  • .dcr
  • .kdc
  • .p7b
  • .p7c
  • .raw
  • .cdr
  • .qbb
  • .indd
  • .qbw

It renames encrypted files using the following names:

  • {original file name and extension}.LOCKED

NOTES:

This Trojan adds the following registry entries to enable its automatic execution every time an encrypted file (files using .LOCKED extension) is opened:

HKEY_CLASSES_ROOT\.LOCKED
(Default) = "TMDCHXKKVCVJWNI"

HKEY_CLASSES_ROOT\TMDCHXKKVCVJWNI\shell\open\command
(Default) = "%User Temp%\hfqKbCfdb5R9xA9.exe"

HKEY_CLASSES_ROOT\Applications\hfqKbCfdb5R9xA9.exe
(Default) = "%User Temp%\hfqKbCfdb5R9xA9.exe

Once a user opens an encrypted file, it opens the following image:

It drops README TO UNLOCK.TXT[ to all drives, folders and sub-folders. The contents of the said file is the same as the text that appears in the image above.

  SOLUTION

Minimum Scan Engine:

9.300

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

Identify and terminate files detected as TROJ_RANSOM.ERA

[ Learn More ]
  1. Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

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_CLASSES_ROOT
    • .LOCKED
  • In HKEY_CLASSES_ROOT
    • TMDCHXKKVCVJWNI
  • In HKEY_CLASSES_ROOT\Applications
    • hfqKbCfdb5R9xA9.exe

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • Alcmeter = "%User Temp%\hfqKbCfdb5R9xA9.exe"

Step 5

Search and delete these files

[ 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.
  • README TO UNLOCK.txt

Step 6

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

Step 7

Restore this file from backup only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on you computer again.

  • {file name}.{file extension}.LOCKED


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