TROJ_CRYPCTB.YVX

May 06, 2015
 ALIASES:

Ransom:Win32/Critroni.B (Microsoft); RDN/Ransom!ex (McAfee); Trojan.Cryptolocker.E (Symantec); Trojan-Ransom.Win32.Foreign.mggj (Kaspersky); Troj/Wonton-QH (Sophos); Win32.Malware!Drop (Sunbelt); Trojan horse Ransomer.HEN (AVG)

 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • 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:

826,880 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

06 May 2015

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.

Other System Modifications

This Trojan modifies the following registry entries:

HKEY_CURRENT_USER\Control Panel\Desktop
TileWallpaper = "0"

(Note: The default value data of the said registry entry is 0.)

HKEY_CURRENT_USER\Control Panel\Desktop
WallpaperStyle = "0"

(Note: The default value data of the said registry entry is 2.)

Dropping Routine

This Trojan drops the following files:

  • %User Temp%\qumnbtg.exe
  • %Windows%\Tasks\hdmomih.job
  • %User Profile%\Microsoft\anhshef
  • %System%\config\systemprofile\My Documents\!Decrypt-All-Files-uxgppre.txt
  • %System%\config\systemprofile\My Documents\!Decrypt-All-Files-uxgppre.bmp
  • %User Profile%\My Documents\!Decrypt-All-Files-uxgppre.txt
  • %User Profile%\My Documents\!Decrypt-All-Files-uxgppre.bmp

(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp 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.. %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.. %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.. %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.750

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

Restore these modified registry values

[ Learn More ]

Important:Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator's help. You may also check out this Microsoft article first before modifying your computer's registry.

  • In HKEY_CURRENT_USER\Control Panel\Desktop
    • From: TileWallpaper = "0"
      To: TileWallpaper = ""0""
  • In HKEY_CURRENT_USER\Control Panel\Desktop
    • From: WallpaperStyle = "0"
      To: WallpaperStyle = ""2""

Step 3

Search and delete these components

[ Learn More ]
There may be some components 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 Temp%\qumnbtg.exe
  • %Windows%\Tasks\hdmomih.job
  • %User Profile%\Microsoft\anhshef
  • %System%\config\systemprofile\My Documents\!Decrypt-All-Files-uxgppre.txt
  • %System%\config\systemprofile\My Documents\!Decrypt-All-Files-uxgppre.bmp
  • %User Profile%\My Documents\!Decrypt-All-Files-uxgppre.txt
  • %User Profile%\My Documents\!Decrypt-All-Files-uxgppre.bmp

Step 4

Scan your computer with your Trend Micro product to delete files detected as TROJ_CRYPCTB.YVX. 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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