RANSOM_CRYPSALAM.A

 Analysis by: Rhena Inocencio

 ALIASES:

Win32/Filecoder.NGG trojan (ESET), RDN/Ransom (McAfee)

 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • 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:

172,032 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

18 Apr 2016

Payload:

Connects to URLs/IPs, Displays message/message boxes, 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):

  • {folders containing encrypted files}\{month}-{day}-{year}-INFECTION.TXT - ransom note
  • {folders containing encrypted files}\{random number}.KEY
  • %My Documents%\{random number}.txt - list of encrypted files

    (Note: %My Documents% is usually C:\Documents and Settings\{user name}\My Documents on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\Documents on Windows Vista and 7.)

Other System Modifications

This Trojan modifies the following file(s):

  • It encrypts files in all fixed and remote (network) drives

Other Details

This Trojan encrypts files with the following extensions:

  • dwg
  • rsa
  • rar
  • dxf
  • dotx
  • rfp
  • pfx
  • psw
  • rpt
  • qbb
  • enz
  • nsf
  • flwa
  • xls
  • xml
  • pgp
  • odt
  • cdr
  • myo
  • xlsm
  • fdb
  • hid2
  • raw
  • ppt
  • flkw
  • 7zip
  • tbl
  • ofx
  • qif
  • mpp
  • qbw
  • aessqlite
  • flk
  • nbf
  • drc
  • idx
  • docm
  • dwk
  • gpg
  • saj
  • gxk
  • sql
  • tar
  • psd
  • dotm
  • prproj
  • mdf
  • mpd
  • accdb
  • max
  • pdf
  • k2p
  • bpw
  • pst
  • dbf
  • gdb
  • qbo
  • arj
  • hid
  • ksd
  • qba
  • tib
  • sdc
  • 4db
  • csv
  • ods
  • ost
  • pdbpptx
  • dot
  • gho
  • bak
  • pps
  • crt
  • db
  • 4dd
  • iso
  • odp
  • dbx
  • alk
  • ppsx
  • nba
  • flka
  • aep
  • 3ds
  • kdbx
  • axxrtf
  • mdb
  • sef
  • doc
  • dwfx
  • crp
  • ai
  • 7z
  • sdf
  • eml
  • xlsx
  • qfx
  • tc
  • accdt
  • ppj
  • docx
  • ifx
  • cer
  • key
  • odb
  • der
  • kdb
  • wdb
  • nv2
  • flkb
  • sko
  • xbrl
  • sxc
  • p12
  • tax

It does the following:

  • It connects to the following URL to report the affected system's information:
      http://{BLOCKED}plin.net/wordpress/wp-includes/oops.php?id=2886098&cname={computer name}&arch={OS architecture}&srv=0&ver={version}

NOTES:

This malware displays the following ransom note in its own window:

The dropped ransom note {month}-{day}-{year}-INFECTION.TXT contains the following message:

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

12.476.01

FIRST VSAPI PATTERN DATE:

18 Apr 2016

VSAPI OPR PATTERN File:

12.477.00

VSAPI OPR PATTERN Date:

19 Apr 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

Identify and terminate files detected as RANSOM_CRYPSALAM.A

[ 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 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}\{month}-{day}-{year}-INFECTION.TXT
  • {folders containing encrypted files}\{random number}.KEY
  • %My Documents%\{random number}.txt

Step 5

Scan your computer with your Trend Micro product to delete files detected as RANSOM_CRYPSALAM.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 6

Restore encrypted files from backup.


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