RANSOM_CRYPAGA.A

June 10, 2016
 Analysis by: Michael Jay Villanueva
 ALIASES:

Ransom:Win32/Pouletcrypt.A (Microsoft); Ransom.Razdaga (Malwarebytes); Trojan.Win32.Inject.wcke (Kaspersky)

 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

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:

98,304 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

06 Jun 2016

Payload:

Encrypts files

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 component file(s):

  • {path of encrypted file}\Instructionaga.txt

It injects codes into the following process(es):

  • csrss.exe

Other System Modifications

This Trojan adds the following registry entries:

HKEY_CURRENT_USER\Software\Exname
Razd1 = {malware filename}

HKEY_CURRENT_USER\Software\what
here = {Random Values}

Other Details

This Trojan encrypts files with the following extensions:

  • .1cd
  • .7z
  • .bmp
  • .cbf
  • .ch
  • .djvu
  • .doc
  • .docx
  • .fbk
  • .gif
  • .jpeg
  • .jpg
  • .ldf
  • .mdf
  • .pdf
  • .png
  • .rar
  • .xls
  • .xlsx
  • .zip

It renames encrypted files using the following names:

  • {original filename}.aga

NOTES:

This ransomware drops the following note:

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

12.572.09

FIRST VSAPI PATTERN DATE:

06 Jun 2016

VSAPI OPR PATTERN File:

12.573.00

VSAPI OPR PATTERN Date:

07 Jun 2016

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\Exname
    • Razd1 = {malware filename}
  • In HKEY_CURRENT_USER\Software\what
    • here = {Random Values}

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.  
  • {path of encrypted file}\Instructionaga.txt

Step 6

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

Scan your computer with your Trend Micro product to delete files detected as RANSOM_CRYPAGA.A. 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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