Analysis by: Janus Agcaoili

ALIASES:

Trojan-Ransom.Win32.CryptXXX.ask (Kaspersky)

 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: 283,648 bytes
File Type: DLL
Memory Resident: Yes
Initial Samples Received Date: 02 Jun 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.

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 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
  • .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
  • .Z3D
  • .ZABW
  • .ZDB
  • .ZDC
  • .ZIF
  • .ZIP
  • .ZIPX
  • .ZW

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}.194.116:443

NOTES:

This ransomware locks the screen and displays the following image:

The ransom note !{unique ID}.html contains the following:

The ransom note contains the following !{unique ID}.txt:

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 12.572.03
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

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.BGZ. 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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