RANSOM_CRYPTLOCK.W

 Analysis by: Pearl Charlaine Espejo

 ALIASES:

Ransom:Win32/Teerac (Microsoft); Ransom.TorrentLocker (Malwarebytes); Ransom.Teerac.A4 (CAT-QuickHeal)

 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet, Spammed via email

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:

278,528 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

26 Nov 2015

Payload:

Connects to URLs/IPs, Displays message/message boxes

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:

  • %Windows%\{random 8 letters}.exe

(Note: %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.)

It drops the following files:

  • %All Users Profile%\Application Data\{random folder name}\00000000
  • %All Users Profile%\Application Data\{random folder name}\01000000
  • %All Users Profile%\Application Data\{random folder name}\02000000

(Note: %All Users Profile% is the All Users folder, where it usually is C:\Documents and Settings\All Users on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\ProgramData 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_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
{random} = "%Windows%\{random 8 letters}.exe"

Other Details

This Trojan connects to the following possibly malicious URL:

  • https://{random}.{BLOCKED}ihs.com/topic.php

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

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

12.230.03

FIRST VSAPI PATTERN DATE:

24 Dec 2015

VSAPI OPR PATTERN File:

12.231.00

VSAPI OPR PATTERN Date:

25 Dec 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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • {random} = "%Windows%\{random 8 letters}.exe"

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.
  • %All Users Profile%\Application Data\{random folder name}\00000000
  • %All Users Profile%\Application Data\{random folder name}\01000000
  • %All Users Profile%\Application Data\{random folder name}\02000000

Step 6

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