This ransomware, known as CryptXXX, is a .DLL file that is capable of locking screens. To avoid analysis, it has routines that makes it aware if it is run in a virtual environment.
To get a one-glance comprehensive view of the behavior of this Trojan, refer to the Threat Diagram shown below.
This malware is a .DLL file known as CryptXXX. It is being distributed by the Angler Exploit Kit. It is capable of locking the screen.
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 terminates itself if it detects it is being run in a virtual environment. It gathers information and reports it to its servers.
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 file(s)/component(s):
- ProgramData\{unique ID}.key
- ProgramData\Z - deleted afterwards. contains installation date of this malware
- {folders containing encrypted files}\{unique ID}.bmp - image used as wallpaper
- {folders containing encrypted files}\{unique ID}.html - ransom note
- {folders containing encrypted files}\{unique ID}.txt - ransom note
where {unique ID} contains 12 hexadecimal characters
It adds the following processes:
- copy of the legitimate rundll32.exe named as:
• %User Temp%\svchost.exe - executes svchost.exe {malware}.dll,MS11{number}
(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp 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.)
It adds the following mutexes to ensure that only one of its copies runs at any one time:
- {first 5 characters from the unique ID}
Autostart Technique
This Trojan drops the following files:
- %User Startup%\{unique ID}.lnk
(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 registry entries:
HKEY_CURRENT_USER\Control Panel\Desktop
TileWallpaper = "0"
HKEY_CURRENT_USER\Control Panel\Desktop
Wallpaper = "{random}\{unique ID}.bmp"
Other Details
This Trojan encrypts files with the following extensions:
- .3DM
- .3DS
- .3G2
- .3GP
- .7Z
- .ACCDB
- .AES
- .AI
- .AIF
- .APK
- .APP
- .ARC
- .ASC
- .ASF
- .ASM
- .ASP
- .ASPX
- .ASX
- .AVI
- .BMP
- .BRD
- .BZ2
- .C
- .CER
- .CFG
- .CFM
- .CGI
- .CGM
- .CLASS
- .CMD
- .CPP
- .CRT
- .CS
- .CSR
- .CSS
- .CSV
- .CUE
- .DB
- .DBF
- .DCH
- .DCU
- .DDS
- .DIF
- .DIP
- .DJV
- .DJVU
- .DOC
- .DOCB
- .DOCM
- .DOCX
- .DOT
- .DOTM
- .DOTX
- .DTD
- .DWG
- .DXF
- .EML
- .EPS
- .FDB
- .FLA
- .FLV
- .FRM
- .GADGET
- .GBK
- .GBR
- .GED
- .GIF
- .GPG
- .GPX
- .GZ
- .H
- .H
- .HTM
- .HTML
- .HWP
- .IBD
- .IBOOKS
- .IFF
- .INDD
- .JAR
- .JAVA
- .JKS
- .JPG
- .JS
- .JSP
- .KEY
- .KML
- .KMZ
- .LAY
- .LAY6
- .LDF
- .LUA
- .M
- .M3U
- .M4A
- .M4V
- .MAX
- .MDB
- .MDF
- .MFD
- .MID
- .MKV
- .MML
- .MOV
- .MP3
- .MP4
- .MPA
- .MPG
- .MS11
- .MSI
- .MYD
- .MYI
- .NEF
- .NOTE
- .OBJ
- .ODB
- .ODG
- .ODP
- .ODS
- .ODT
- .OTG
- .OTP
- .OTS
- .OTT
- .P12
- .PAGES
- .PAQ
- .PAS
- .PCT
- .PDB
- .PDF
- .PEM
- .PHP
- .PIF
- .PL
- .PLUGIN
- .PNG
- .POT
- .POTM
- .POTX
- .PPAM
- .PPS
- .PPSM
- .PPSX
- .PPT
- .PPTM
- .PPTX
- .PRF
- .PRIV
- .PRIVAT
- .PS
- .PSD
- .PSPIMAGE
- .PY
- .QCOW2
- .RA
- .RAR
- .RAW
- .RM
- .RSS
- .RTF
- .SCH
- .SDF
- .SH
- .SITX
- .SLDX
- .SLK
- .SLN
- .SQL
- .SQLITE
- .SQLITE
- .SRT
- .STC
- .STD
- .STI
- .STW
- .SVG
- .SWF
- .SXC
- .SXD
- .SXI
- .SXM
- .SXW
- .TAR
- .TBK
- .TEX
- .TGA
- .TGZ
- .THM
- .TIF
- .TIFF
- .TLB
- .TMP
- .TXT
- .UOP
- .UOT
- .VB
- .VBS
- .VCF
- .VCXPRO
- .VDI
- .VMDK
- .VMX
- .VOB
- .WAV
- .WKS
- .WMA
- .WMV
- .WPD
- .WPS
- .WSF
- .XCODEPROJ
- .XHTML
- .XLC
- .XLM
- .XLR
- .XLS
- .XLSB
- .XLSM
- .XLSX
- .XLT
- .XLTM
- .XLTX
- .XLW
- .XML
- .YUV
- .ZIP
- .ZIPX
It renames encrypted files using the following names:
- {original file name.file extension}.crypt
It terminates itself if it detects it is being run in a virtual environment.
It gathers the following information and reports it to its servers:
- It reports infection status and unique ID to {BLOCKED}.{BLOCKED}.13.153
NOTES:
This malware is a .DLL file known as CryptXXX. It is being distributed by the Angler Exploit Kit. It is capable of locking the screen.
The following is the content of {unique ID}.key:
The following is the content of ProgramData\Z:
It locks the screen and displays the following:
{unique ID}.bmp:
{unique ID}.txt:
{unique ID}.html:
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
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To restart in Safe Mode:
• For Windows 2000 users
- Restart your computer.
- Press F8 when you see the Starting Windows bar at the bottom of the screen.
- Choose the Safe Mode option from the Windows Advanced Options menu then press Enter.
• For Windows XP users
- Restart your computer.
- Press F8 after the Power-On Self Test (POST) routine is done. If the Windows Advanced Options menu does not appear, try restarting then pressing F8 several times when the POST screen appears.
- Choose the Safe Mode option from the Windows Advanced Options menu then press Enter.
• For Windows Server 2003 users
- Restart your computer.
- Press F8 after Windows starts up. If the Windows Advanced Options menu does not appear, try restarting again and pressing F8 several times afterward.
- On the Windows Advanced Option menu, use the arrow keys to select Safe Mode then press Enter.
• For Windows Vista, Windows 7, and Windows Server 2008 users
- Restart your computer.
- Press F8 after the Power-On Self Test (POST) routine is done. If the Advanced Boot Options menu does not appear, try restarting and then pressing F8 several times after the POST screen is displayed.
- On the Advanced Boot Options menu, use the arrow keys to select the Safe Mode option, and then press Enter.
• For Windows 8, Windows 8.1, and Windows Server 2012 users
- Access the Charms bar by moving your mouse pointer to the upper right corner of the screen.
- Move your mouse pointer down and click Settings>Change your PC Settings.
- In the left panel, click General.
- In the right panel, scroll down to the bottom to find the Advanced startup section, then click the Restart now button and wait for the system to restart.
- In the Advanced Startup menu, click Troubleshoot>Advanced Options>Startup Settings>Restart and wait for the system to restart.
- In the Startup Settings menu, press 4 to enable safe mode.
Step 4
Restore this modified registry value
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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\Control Panel\Desktop
- Wallpaper = "{random}\{unique ID}.bmp"
- In HKEY_CURRENT_USER\Control Panel\Desktop
To restore the registry value this malware/grayware modified:
- Open Registry Editor.
» For Windows 2000, Windows XP, and Windows Server 2003 users, click Start>Run, type regedit in the text box provided, and then press Enter.
» For Windows Vista, Windows 7, and Windows Server 2008 users, click the Start button, type regedit in the Search input field then press Enter.
» For Windows 8, Windows 8.1, and Windows Server 2012 users, right-click on the lower left corner of the screen, click Run, type regedit in the text box provided, and then press Enter. - In the left panel, double-click the following:
HKEY_CURRENT_USER>Control Panel>Desktop - In the right panel, locate the registry value:
Wallpaper = "{random}\{unique ID}.bmp" - Again In the right panel, locate the registry value:
TileWallpaper = "0" - Close Registry Editor.
Step 5
Search and delete this file
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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.
- ProgramData\{unique ID}.key
- %User Startup%\{unique ID}.lnk
- {folders containing encrypted files}\{unique ID}.bmp
- {folders containing encrypted files}\{unique ID}.html
- {folders containing encrypted files}\{unique ID}.txt
To manually delete a malware/grayware file from an affected system:
• For Windows 2000, Windows XP, and Windows Server 2003:
- Right-click Start then click Search....
- In the File name* input box, type the following:
- ProgramData\{unique ID}.key
- %User Startup%\{unique ID}.lnk
- {folders containing encrypted files}\{unique ID}.bmp
- {folders containing encrypted files}\{unique ID}.html
- {folders containing encrypted files}\{unique ID}.txt
- In the Look In drop-down list, select My Computer then press Enter.
- Once located, select the file then press SHIFT+DELETE to delete it.
*Note: The file name input box title varies depending on the Windows version (e.g. Search for files or folders named or All or part of the file name.).
• For Windows Vista, Windows 7, Windows Server 2008, Windows 8, Windows 8.1, and Windows Server 2012:
- Open a Windows Explorer window.
- For Windows Vista, 7, and Server 2008 users, click Start>Computer.
- For Windows 8, 8.1, and Server 2012 users, right-click on the lower left corner of the screen, then click File Explorer.
- In the Search Computer/This PC input box, type:
- ProgramData\{unique ID}.key
- %User Startup%\{unique ID}.lnk
- {folders containing encrypted files}\{unique ID}.bmp
- {folders containing encrypted files}\{unique ID}.html
- {folders containing encrypted files}\{unique ID}.txt
- Once located, select the file then press SHIFT+DELETE to delete it.
*Note: Read the following Microsoft page if these steps do not work on Windows 7.
Step 6
Restart in normal mode and scan your computer with your Trend Micro product for files detected as RANSOM_WALTRIX.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 7
Restore encrypted files from backup.
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