Analysis by: Augusto II Remillano
ALIASES:

Gen:Variant.Symmi.65725 (BitDefender), Trojan-Ransom.Win32.Zerber.fhql (Kaspersky), Trojan horse Crypt8.BPVR (AVG)

 PLATFORM:

Windows

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

  • Threat Type: Ransomware

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

Infection Channel: Dropped by other malware

This Ransomware arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It deletes the initially executed copy of itself. It is capable of encrypting files in the affected system.

It drops files as ransom note.

  TECHNICAL DETAILS

File Size: 127,488 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 21 May 2018
Payload: Encrypts files

Arrival Details

This Ransomware 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 Ransomware changes the desktop wallpaper by modifying the following registry entries:

HKEY_CURRENT_USER\Control Panel\Desktop
Wallpaper = %User Temp%\tmp*.bmp

Other Details

This Ransomware renames encrypted files using the following names:

  • {10 Random Alphanumeric Characters}.cerber

It deletes the initially executed copy of itself

It accesses the following URL(s) to get the affected system's location:

  • http://{BLOCKED}.{BLOCKED}/json

It is capable of encrypting files in the affected system.

Ransomware Routine

This Ransomware drops the following file(s) as ransom note:

  • {folders containing encrypted files}\# DECRYPT MY FILES #.txt
  • {folders containing encrypted files}\# DECRYPT MY FILES #.vbs
  • {folders containing encrypted files}\# DECRYPT MY FILES #.html
  • {folders containing encrypted files}\# DECRYPT MY FILES #.url

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 14.264.06
FIRST VSAPI PATTERN DATE: 21 May 2018
VSAPI OPR PATTERN File: 14.265.00
VSAPI OPR PATTERN Date: 22 May 2018

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

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\Control Panel\Desktop
    • Wallpaper = %User Temp%\tmp*.bmp

Step 4

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.
  • {folders containing encrypted files}\# DECRYPT MY FILES #.txt
  • {folders containing encrypted files}\# DECRYPT MY FILES #.vbs
  • {folders containing encrypted files}\# DECRYPT MY FILES #.html
  • {folders containing encrypted files}\# DECRYPT MY FILES #.url
  • %User Temp%\tmp*.bmp

Step 5

Scan your computer with your Trend Micro product to delete files detected as RANSOM_CERBER.THEBAAH. 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 the following Trend Micro Support pages for more information:

Step 6

Reset your Desktop properties

[ Learn More ]

Step 7

Restore encrypted files from backup.


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