Analysis by: Rhena Inocencio

ALIASES:

Trojan:Win32/Dorv.C!rfn (Microsoft), Trojan-Ransom.Win32.CryptXXX.ako (Kaspersky), a variant of Win32/Kryptik.EYLM (ESET)

 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: Varies
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 30 May 2016
Payload: Connects to URLs/IPs, Encrypts files, Displays message/message boxes

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.

This malware arrives via the following means:

  • delivered by exploit kits

Installation

This Trojan drops the following files:

  • %User Startup%\!{unique ID}{random character 1}.lnk - component that automatically opens the image ransom note upon system startup
  • %User Startup%\!{unique ID}{random character 2}.lnk - component that automatically opens the HTML ransom note upon system startup
    where {unique ID} contains 12 hexadecimal characters
  • %ProgramData%\Z - deleted afterwards. This contains the installation date of the malware
  • %ProgramData%\!{unique ID}.key - deleted afterwards
  • %ProgramData%\!{unique ID}.bmp - lockscreen image
  • %ProgramData%\!{unique ID}.html - ransom note
  • %Desktop%\!{unique ID}.bmp - ransom image
  • %Desktop%\!{unique ID}.html - ransom note
  • %Desktop%\!{unique ID}.txt - ransom note
  • {folders containing encrypted files}\!{unique ID}.html - ransom note
  • {folders containing encrypted files}\!{unique ID}.txt - ransom note

(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.. %ProgramData% is the Program Data folder, where it usually is C:\Program Files in Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\ProgramData in 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.. %Desktop% is the desktop folder, where it usually is C:\Documents and Settings\{user name}\Desktop in Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\Desktop in 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.)

It drops the following file(s)/component(s):

    It adds the following processes:

    • {malware path}\rundll32.exe {malware path and filename}.dll,MSX{number}

      It copies the legitimate rundll32.exe to the same directory of the ransomware.

    Autostart Technique

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

    • %User Startup%\!{unique ID}.lnk
      where {unique ID} contains 12 hexadecimal characters

    (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.)

    Other System Modifications

    This Trojan modifies the following file(s):

    • It encrypts files and appends the extension .cryp1

    Other Details

    This Trojan encrypts files with the following extensions:

    • .LYT
    • .LYX
    • .M
    • .M3D
    • .M3U
    • .M4A
    • .M4V
    • .MA
    • .MAC
    • .MAN
    • .MAP
    • .MAQ
    • .MAT
    • .MAX
    • .MB
    • .MBM
    • .MBOX
    • .MDB
    • .MDF
    • .MDN
    • .MDT
    • .ME
    • .MEF
    • .MELL
    • .MFD
    • .MFT
    • .MGCB
    • .MGMT
    • .MGMX
    • .MID
    • .MIN
    • .MKV
    • .MMAT
    • .MML
    • .MNG
    • .MNR
    • .MNT
    • .MOBI
    • .MOS
    • .MOV
    • .MP3
    • .MP4
    • .MPA
    • .MPF
    • .MPG
    • .MPO
    • .MRG
    • .MRXS
    • .MS11
    • .MSG
    • .MSI
    • .MT9
    • .MUD
    • .MWB
    • .MWP
    • .MXL
    • .MYD
    • .MYI
    • .MYL
    • .NCR
    • .NCT
    • .NDF
    • .NEF
    • .NFO
    • .NJX
    • .NLM
    • .NOTE
    • .NOW
    • .NRW
    • .NS2
    • .NS3
    • .NS4
    • .NSF
    • .NV2
    • .NYF
    • .NZB
    • .OBJ
    • .OC3
    • .OC4
    • .OC5
    • .OCE
    • .OCI
    • .OCR
    • .ODB
    • .ODG
    • .ODM
    • .ODO
    • .ODP
    • .ODS
    • .ODT
    • .OFL
    • .OFT
    • .OMF
    • .OPLC
    • .OQY
    • .ORA
    • .ORF
    • .ORT
    • .ORX
    • .OTA
    • .OTG
    • .OTI
    • .OTP
    • .OTS
    • .OTT
    • .OVP
    • .OVR
    • .OWC
    • .OWG
    • .OYX
    • .OZB
    • .OZJ
    • .OZT
    • .P12
    • .P7S
    • .P96
    • .P97
    • .PAGES
    • .PAL
    • .PAN
    • .PANO
    • .PAP
    • .PAQ
    • .PAS
    • .PB
    • .PBM
    • .PC1
    • .PC2
    • .PC3
    • .PCD
    • .PCS
    • .PCT
    • .PCX
    • .PDB
    • .PDD
    • .PDF
    • .PDM
    • .PDN
    • .PDS
    • .PDT
    • .PE4
    • .RT
    • .RTD
    • .RTF
    • .RTX
    • .RUN
    • .RW2
    • .RWL
    • .RZK
    • .RZN
    • .S2MV
    • .S3M
    • .SAF
    • .SAI
    • .SAM
    • .SAVE
    • .SBF
    • .SCAD
    • .SCC
    • .SCH
    • .SCI
    • .SCM
    • .SCT
    • .SCV
    • .SCW
    • .SDB
    • .SDF
    • .SDM
    • .SDOC
    • .SDW
    • .SEP
    • .SFC
    • .SFW
    • .SGM
    • .SH
    • .SIG
    • .SITX
    • .SK1
    • .SK2
    • .SKM
    • .SLA
    • .SLD
    • .SLDX
    • .SLK
    • .SLN
    • .SLS
    • .SMF
    • .SMIL
    • .SMS
    • .SOB
    • .SPA
    • .SPE
    • .SPH
    • .SPJ
    • .SPP
    • .SPQ
    • .SPR
    • .SQB
    • .SQL
    • .SQLITE3
    • .SQLITEDB
    • .SR2
    • .SRT
    • .SRW
    • .SSA
    • .SSK
    • .ST
    • .STC
    • .STD
    • .STE
    • .STI
    • .STM
    • .STN
    • .STP
    • .STR
    • .STW
    • .STY
    • .SUB
    • .SUMO
    • .SVA
    • .SVF
    • .SVG
    • .SVGZ
    • .SWF
    • .SXC
    • .SXD
    • .SXG
    • .SXI
    • .SXM
    • .SXW
    • .T2B
    • .TAB
    • .TAR
    • .TB0
    • .TBK
    • .TBN
    • .TCX
    • .TDF
    • .TDT
    • .TE
    • .TEX
    • .TEXT
    • .TF
    • .TFC
    • .TG4
    • .TGA
    • .TGZ
    • .THM
    • .THP
    • .TIF
    • .TIFF
    • .TJP
    • .TLB
    • .TLC
    • .TM
    • .TM2
    • .TMD
    • .TMP
    • .TMV
    • .TMX
    • .TN
    • .TNE
    • .TPC
    • .TPI
    • .TRM
    • .TVJ
    • .TXT
    • .U3D
    • .U3I
    • .UDB
    • .UFO
    • .UFR
    • .UGA
    • .UNX
    • .UOF
    • .UOP
    • .UOT
    • .UPD
    • .USR
    • .UTF8
    • .UTXT
    • .V12
    • .VB
    • .VBR
    • .VBS
    • .VCF
    • .VCT
    • .VCXPROJ
    • .VDA
    • .VDB
    • .VDI
    • .VEC
    • .VFF
    • .VMDK
    • .VML
    • .VMX
    • .VNT
    • .VOB
    • .VPD
    • .VPE
    • .VRML
    • .VRP
    • .VSD
    • .VSDM
    • .VSDX
    • .VSM
    • .VST
    • .VSTX
    • .VUE
    • .VW
    • .WAV
    • .WB1
    • .WBC
    • .WBD
    • .WBK
    • .WBM
    • .WBMP
    • .WBZ
    • .WCF
    • .WDB
    • .WDP
    • .WEBP
    • .WGZ
    • .WIRE
    • .WKS
    • .WMA
    • .WMDB
    • .WMF
    • .WMV
    • .WN
    • .WP
    • .WP4
    • .WP5
    • .WP6
    • .WP7
    • .WPA
    • .WPD
    • .WPE
    • .WPG
    • .WPL
    • .WPS
    • .WPT
    • .WPW
    • .WRI
    • .WSC
    • .WSD
    • .WSF
    • .WSH
    • .WTX
    • .WVL
    • .X3D
    • .X3F
    • .XAR
    • .XCODEPROJ
    • .XDB
    • .XDL
    • .XHTM
    • .XHTML
    • .XLC
    • .XLD
    • .XLF
    • .XLGC
    • .XLM
    • .XLR
    • .XLS
    • .XLSB
    • .XLSM
    • .XLSX
    • .XLT
    • .XLTM
    • .XLTX
    • .XLW
    • .XML
    • .XPM
    • .XPS
    • .XWP
    • .XY3
    • .XYP
    • .XYW
    • .YAL
    • .YBK
    • .YML
    • .YSP
    • .YUV
    • .Z3D
    • .ZABW
    • .ZDB
    • .ZDC
    • .ZIF
    • .ZIP
    • .ZIPX
    • .ZW
    • .3DM
    • .3DS
    • .3G2
    • .3GP
    • .4DB
    • .4DL
    • .4MP
    • .7Z
    • .A3D
    • .ABM
    • .ABS
    • .ABW
    • .ACCDB
    • .ACT
    • .ADN
    • .ADP
    • .AES
    • .AF2
    • .AF3
    • .AFT
    • .AFX
    • .AGIF
    • .AGP
    • .AHD
    • .AI
    • .AIC
    • .AIF
    • .AIM
    • .ALBM
    • .ALF
    • .ANI
    • .ANS
    • .APD
    • .APK
    • .APM
    • .APNG
    • .APP
    • .APS
    • .APT
    • .APX
    • .ARC
    • .ART
    • .ARW
    • .ASC
    • .ASE
    • .ASF
    • .ASK
    • .ASM
    • .ASP
    • .ASPX
    • .ASW
    • .ASX
    • .ASY
    • .ATY
    • .AVI
    • .AWDB
    • .AWP
    • .AWT
    • .AWW
    • .AZZ
    • .BAD
    • .BAY
    • .BBS
    • .BDB
    • .BDP
    • .BDR
    • .BEAN
    • .BIB
    • .BM2
    • .BMP
    • .BMX
    • .BNA
    • .BND
    • .BOC
    • .BOK
    • .BRD
    • .BRK
    • .BRN
    • .BRT
    • .BSS
    • .BTD
    • .BTI
    • .BTR
    • .BZ2
    • .C
    • .C2
    • .C4
    • .C4D
    • .CAL
    • .CALS
    • .CAN
    • .CD5
    • .CDB
    • .CDC
    • .CDG
    • .CDMM
    • .CDMT
    • .CDR
    • .CDR3
    • .CDR4
    • .CDR6
    • .CDT
    • .CER
    • .CF
    • .CFG
    • .CFM
    • .CFU
    • .CGI
    • .CGM
    • .CIMG
    • .CIN
    • .CIT
    • .CKP
    • .CLASS
    • .CLKW
    • .CMA
    • .CMD
    • .CMX
    • .CNM
    • .CNV
    • .COLZ
    • .CPC
    • .CPD
    • .CPG
    • .CPP
    • .CPS
    • .CPT
    • .CPX
    • .CRD
    • .CRT
    • .CRWL
    • .CRYPT
    • .CS
    • .CSR
    • .CSS
    • .CSV
    • .CSY
    • .CUE
    • .CV5
    • .CVG
    • .CVI
    • .CVS
    • .CVX
    • .CWT
    • .CXF
    • .CYI
    • .DAD
    • .DAF
    • .DB
    • .DB3
    • .DBF
    • .DBK
    • .DBT
    • .DBV
    • .DBX
    • .DCA
    • .DCB
    • .DCH
    • .DCS
    • .DCT
    • .DCU
    • .DCX
    • .DDL
    • .DDOC
    • .DDS
    • .DED
    • .DF1
    • .DG
    • .DGN
    • .DGS
    • .DHS
    • .DIB
    • .DIF
    • .DIP
    • .DIZ
    • .DJV
    • .DJVU
    • .DM3
    • .DMI
    • .DMO
    • .DNC
    • .DNE
    • .DOC
    • .DOCB
    • .DOCM
    • .DOCX
    • .DOCZ
    • .DOT
    • .DOTM
    • .DOTX
    • .DP1
    • .DPP
    • .DPX
    • .DQY
    • .DRW
    • .DRZ
    • .DSK
    • .DSN
    • .DSV
    • .DT
    • .DT2
    • .DTA
    • .DTD
    • .DTSX
    • .DTW
    • .DVI
    • .DVL
    • .DWG
    • .DX
    • .DXB
    • .DXF
    • .DXL
    • .ECO
    • .ECW
    • .ECX
    • .EDB
    • .EFD
    • .EGC
    • .EIO
    • .EIP
    • .EIT
    • .EMD
    • .EMF
    • .EML
    • .EMLX
    • .EP
    • .EPF
    • .EPP
    • .EPS
    • .EPSF
    • .EQL
    • .ERF
    • .ERR
    • .ETF
    • .ETX
    • .EUC
    • .EXR
    • .FAL
    • .FAQ
    • .FAX
    • .FB2
    • .FB3
    • .FBL
    • .FBX
    • .FCD
    • .FCF
    • .FDB
    • .FDF
    • .FDR
    • .FDS
    • .FDT
    • .FDX
    • .FDXT
    • .FES
    • .FFT
    • .FH10
    • .FH11
    • .FH3
    • .FH4
    • .FH5
    • .FH6
    • .FH7
    • .FH8
    • .FIC
    • .FID
    • .FIF
    • .FIG
    • .FIL
    • .FL
    • .FLA
    • .FLI
    • .FLR
    • .FLV
    • .FM5
    • .FMV
    • .FODT
    • .FOL
    • .FP3
    • .FP4
    • .FP5
    • .FP7
    • .FPOS
    • .FPT
    • .FPX
    • .FRM
    • .FRT
    • .FT10
    • .FT11
    • .FT7
    • .FT8
    • .FT9
    • .FTN
    • .FWDN
    • .FXC
    • .FXG
    • .FZB
    • .FZV
    • .GADGET
    • .GBK
    • .GBR
    • .GCDP
    • .GDB
    • .GDOC
    • .GED
    • .GEM
    • .GEO
    • .GFB
    • .GGR
    • .GIF
    • .GIH
    • .GIM
    • .GIO
    • .GLOX
    • .GPD
    • .GPG
    • .GPN
    • .GPX
    • .GRO
    • .GROB
    • .GRS
    • .GSD
    • .GTHR
    • .GTP
    • .GV
    • .GWI
    • .GZ
    • .H
    • .HBK
    • .HDB
    • .HDP
    • .HDR
    • .HHT
    • .HIS
    • .HPG
    • .HPGL
    • .HPI
    • .HPL
    • .HS
    • .HTC
    • .HTM
    • .HTML
    • .HWP
    • .HZ
    • .I3D
    • .IB
    • .IBD
    • .IBOOKS
    • .ICN
    • .ICON
    • .IDC
    • .IDEA
    • .IDX
    • .IFF
    • .IGT
    • .IGX
    • .IHX
    • .IIL
    • .IIQ
    • .IMD
    • .INDD
    • .INFO
    • .INK
    • .IPF
    • .IPX
    • .ITDB
    • .ITW
    • .IWI
    • .J2C
    • .J2K
    • .JAR
    • .JAS
    • .JAVA
    • .JB2
    • .JBMP
    • .JBR
    • .JFIF
    • .JIA
    • .JIS
    • .JKS
    • .JNG
    • .JOE
    • .JP1
    • .JP2
    • .JPE
    • .JPEG
    • .JPG
    • .JPG2
    • .JPS
    • .JPX
    • .JRTF
    • .JS
    • .JSP
    • .JTX
    • .JWL
    • .JXR
    • .KDB
    • .KDBX
    • .KDC
    • .KDI
    • .KDK
    • .KES
    • .KEY
    • .KIC
    • .KLG
    • .KML
    • .KMZ
    • .KNT
    • .KON
    • .KPG
    • .KWD
    • .LAY
    • .LAY6
    • .LBM
    • .LBT
    • .LDF
    • .LGC
    • .LIS
    • .LIT
    • .LJP
    • .LMK
    • .LNT
    • .LP2
    • .LRC
    • .LST
    • .LTR
    • .LTX
    • .LUA
    • .LUE
    • .LUF
    • .LWO
    • .LWP
    • .LWS

    It does the following:

    • It deletes shadow copies using vssadmin.exe
    • It deletes itself as well as its LNK startup after the user chooses to reboot the system
    • It locks the screen after file encryption routine
    • It avoids to encrypt the following files/folders:
      • \WINNT
      • \RECYCLER\
      • \SYSTEM~1\
      • \BOOT\
      • \RECOVERY\
      • \$RECYCLE.BIN\
      • \PERFLOGS\
      • \EFI\
      • \CONFIG.MSI\
      • \PROGRA~1\
      • \PROGRA~2\
      • \GOOGLE\
      • \TEMP\
      • \F4BC~1\
      • \ALLUSE~1\
      • \PROGRA~1\
      • \PROGRA~2\
      • \APPDATA\
      • \PROGRA~3\
      • \PUBLIC\
      • AUTOEXEC.BAT
      • THUMBS.DB
      • \APPLIC~1\
      • \COOKIES\
      • \LOCALS~1\
      • \TEMPLA~1\
    • It reports infection status and unique ID to {BLOCKED}.{BLOCKED}.194.116

    NOTES:

    This ransomware locks the screen and displays the following image:

    Below is the content of the ransom note !{unique ID}.html:

      SOLUTION

    Minimum Scan Engine: 9.800
    FIRST VSAPI PATTERN FILE: 12.558.07
    FIRST VSAPI PATTERN DATE: 30 May 2016
    VSAPI OPR PATTERN File: 12.559.00
    VSAPI OPR PATTERN Date: 31 May 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

    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.
    • %User Startup%\!{unique ID}.lnk
    • %User Startup%\!{unique ID}{random character 1}.lnk
    • %User Startup%\!{unique ID}{random character 2}.lnk
    • !{unique ID}.bmp
    • !{unique ID}.html
    • !{unique ID}.txt

    Step 5

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