RANSOM_CRYSIS.C

 Analysis by: Michael Jay Villanueva

 ALIASES:

Trojan:Win32/Dynamer!ac (Microsoft)

 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, Dropped by other malware

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.

It does not have any propagation routine.

It does not have any backdoor routine.

It modifies the Internet Explorer Zone Settings.

  TECHNICAL DETAILS

File Size:

268,288 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

18 Jan 2017

Payload:

Connects to URLs/IPs, Encrypts files, Displays graphics/image

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 files:

  • %Desktop%\Decryption instructions webmafia@india.com recovery.txt -> Ransom Note
  • %Application Data%\Info.hta -> Ransom Note
  • %User Startup%\Info.hta -> Ransom Note

It drops the following copies of itself into the affected system:

  • %Application Data%\{Malware Filename}.exe
  • %System%\{Malware Filename}.exe

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming 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.. %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

Autostart Technique

This Trojan adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
{Malware Filename} = "%System%\{Malware Filename}.exe"

HKEY_CURRENT_USER\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
{Malware Filename} = "%Application Data%\{Malware Filename}.exe"

It drops the following file(s) in the Windows User Startup folder to enable its automatic execution at every system startup:

  • %User Startup%\{Malware Filename}.exe -> copy of the malware, also detected as Ransom_CRYSIS.C

(Note: %User Startup% is the current user's Startup folder, which is usually C:\Documents and Settings\{user}\Start Menu\Programs\Startup on Windows 2000 and XP, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup on Windows Vista, 7, and 8.)

It drops the following file(s) in the Windows Startup folder to enable its automatic execution at every system startup:

  • %All Users Profile%\Microsoft\Windows\Start Menu\Programs\Startup\{Malware Filename}.exe

(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.)

Propagation

This Trojan does not have any propagation routine.

Backdoor Routine

This Trojan does not have any backdoor routine.

Web Browser Home Page and Search Page Modification

This Trojan modifies the Internet Explorer Zone Settings.

Other Details

This Trojan encrypts files with the following extensions:

  • .3g2
  • .3gp
  • .3fr
  • .accda
  • .3ds
  • .accdb
  • .accdc
  • .accde
  • .accdt
  • .accdw
  • .adb
  • .adp
  • .ai3
  • .ai4
  • .ai5
  • .ai6
  • .ai7
  • .ai8
  • .anime
  • .arw
  • .asa
  • .asc
  • .ascx
  • .asm
  • .asmx
  • .asp
  • .aspx
  • .asr
  • .asx
  • .avi
  • .avs
  • .backup
  • .bak
  • .bay
  • .bin
  • .bmp
  • .bz2
  • .cdr
  • .cer
  • .cfc
  • .cfm
  • .cfml
  • .cfu
  • .chm
  • .cin
  • .class
  • .clx
  • .config
  • .cpp
  • .cr2
  • .crt
  • .crw
  • .css
  • .csv
  • .cub
  • .dae
  • .dat
  • .dbf
  • .dbx
  • .dc3
  • .dcm
  • .dcr
  • .der
  • .dib
  • .ob
  • .dic
  • .dif
  • .div
  • .djvu
  • .exe
  • .ini
  • .iqy
  • .j2c
  • .p1
  • .j2k
  • .java
  • .jp2
  • .jpc
  • .jpe
  • .pf
  • .jpeg
  • .jpf
  • .jpg
  • .jpx
  • .jsf
  • .pl
  • .json
  • .jsp
  • .po
  • .kdc
  • .pp
  • .kmz
  • .kwm
  • .lasso
  • .lbi
  • .lgf
  • .lgp
  • .log
  • .m1v
  • .m4a
  • .m4v
  • .max
  • .mda
  • .mdb
  • .mde
  • .sd
  • .mdf
  • .sh
  • .mdw
  • .sl
  • .mef
  • .mft
  • .mfw
  • .mht
  • .mhtml
  • .mka
  • .mkidx
  • .mkv
  • .tim
  • .mos
  • .mov
  • .tw
  • .mp3
  • .mp4
  • .mpeg
  • .mpg
  • .mpv
  • .mrw
  • .msg
  • .mxl
  • .vt
  • .myd
  • .myi
  • .nef
  • .nrw
  • .obj
  • .odb
  • .odc
  • .odm
  • .odp
  • .ods
  • .oft
  • .one
  • .onepkg
  • .opt
  • .oqy
  • .orf
  • .p12
  • .p7b
  • .p7c
  • .pam
  • .pbm
  • .pct
  • .pcx
  • .pdd
  • .pdf
  • .pdp
  • .pef
  • .pem
  • .pff
  • .pfm
  • .pfx
  • .pgm
  • .php
  • .php3
  • .php4
  • .php5
  • .phtml
  • .pict
  • .pls
  • .png
  • .pnm
  • .pot
  • .potm
  • .potx
  • .ppa
  • .ppam
  • .ppm
  • .pps
  • .ppsm
  • .ppt
  • .pptm
  • .pptx
  • .prn
  • .psb
  • .psd
  • .pst
  • .ptx
  • .pub
  • .pwm
  • .pxr
  • .r3d
  • .raf
  • .rar
  • .raw
  • .rdf
  • .rgbe
  • .rle
  • .rqy
  • .rss
  • .rtf
  • .rw2
  • .rwl
  • .safe
  • .sct
  • .sdpx
  • .shtm
  • .shtml
  • .slk
  • .sln
  • .sql
  • .sr2
  • .srf
  • .srw
  • .ssi
  • .stm
  • .svg
  • .svgz
  • .swf
  • .tab
  • .tar
  • .tbb
  • .tbi
  • .tbk
  • .tdi
  • .tga
  • .thmx
  • .tif
  • .tiff
  • .tld
  • .tpl
  • .txt
  • .u3d
  • .udl
  • .url
  • .uxdc
  • .vbs
  • .vcs
  • .vda
  • .vdr
  • .vdw
  • .vdx
  • .vrp
  • .vsd
  • .vss
  • .vst
  • .vsw
  • .vsx
  • .vtm
  • .vtml
  • .vtx
  • .wb2
  • .wav
  • .wbm
  • .wbmp
  • .wim
  • .wmf
  • .wml
  • .wmv
  • .wpd
  • .wps
  • .x3f
  • .xla
  • .xlam
  • .xlk
  • .xlm
  • .xls
  • .xlsb
  • .xlsm
  • .xlsx
  • .xlt
  • .xltm
  • .xltx
  • .xlw
  • .xml
  • .xps
  • .xsd
  • .xsf
  • .xsl
  • .xslt
  • .xsn
  • .xtp
  • .xtp2
  • .xyze
  • .zip
  • .wallet

It renames encrypted files using the following names:

  • {Original Filename and Extension}.[webmafia@asia.com].wallet

It does the following:

  • It deletes shadow copies by executing the following command:
    • vssadmin delete shadows /all /quiet
  • It avoids encrypting files/directories with the following strings:
    • %windir%
    • boot.ini
    • bootfont.bin
    • ntldr
    • ntdetect.com
    • io.sys
    • explorer.exe
    • svchost.exe
  • It executes the following commands:
    mode con cp select=1251
  • It encrypts files in all fixed, remote and removable drives.

NOTES:

It displays the following ransom notes after encrypting the target files:

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

13.166.02

FIRST VSAPI PATTERN DATE:

19 Jan 2017

VSAPI OPR PATTERN File:

13.167.00

VSAPI OPR PATTERN Date:

20 Jan 2017

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

Identify and terminate files detected as RANSOM_CRYSIS.C

[ 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 5

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\Microsoft\Windows\CurrentVersion\Run
    • {Malware Filename} = "%System%\{Malware Filename}.exe"
  • In HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • {Malware Filename} = "%Application Data%\{Malware Filename}.exe"

Step 6

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.
  • %Desktop%\Decryption instructions webmafia@india.com recovery.txt
  • %Application Data%\Info.hta
  • %User Startup%\Info.hta

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as RANSOM_CRYSIS.C. 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 8

Restore encrypted files from backup.

Step 9

Reset Internet security settings

[ Learn More ]

Step 10

Scan your computer with your Trend Micro product to delete files detected as RANSOM_CRYSIS.C. 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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