TROJ_CRYPCTB.J
VirTool:Win32/CeeInject.gen!KK (Microsoft), Trojan.Win32.Inject.tpsl (Kaspersky), a variant of Win32/Injector.BRCN trojan (ESET)
Windows
Threat Type: Trojan
Destructiveness: No
Encrypted: Yes
In the wild: Yes
OVERVIEW
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.
TECHNICAL DETAILS
1,031,726 bytes
EXE
Yes
12 Dec 2014
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 files:
- %User Profile%\My Documents\Decrypt All Files {random characters}.bmp - image used as wallpaper
- %User Profile%\My Documents\Decrypt All Files {random characters}.txt - ransom note in text file
- %User Profile%\My Documents\{random characters}.html - contains ransom note and list of encrypted files
(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)
It drops the following copies of itself into the affected system:
- %User Temp%\{random filename}.exe
(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.)
Autostart Technique
This Trojan drops the following files:
- C:\Windows\Tasks\{random filename}.job
Other System Modifications
This Trojan modifies the following registry entries:
HKEY_CURRENT_USER\Control Panel\Desktop
Wallpaper = "%User Profile%\My Documents\Decrypt All Files {random characters}.bmp"
(Note: The default value data of the said registry entry is {user-defined}.)
Other Details
This Trojan encrypts files with the following extensions:
- pwm
- kwm
- safe
- groups
- txt
- cer
- crt
- der
- pem
- doc
- docm
- docx
- rtf
- xlk
- xls
- xlsb
- xlsm
- xlsx
- mdb
- mdf
- dbf
- db
- sql
- md
- dd
- dds
- jpe
- jpg
- jpeg
- cr2
- raw
- rw2
- rwl
- dwg
- dxf
- dxg
- psd
- 3fr
- accdb
- ai
- arw
- bay
- blend
- cdr
- crw
- dcr
- dng
- eps
- erf
- indd
- kdc
- mef
- mrw
- nef
- nrw
- odb
- odm
- odp
- ods
- odt
- orf
- p12
- p7b
- p7c
- pdd
- pef
- pfx
- ppt
- pptm
- pptx
- pst
- ptx
- r3d
- raf
- srf
- srw
- wb2
- vsd
- wpd
- wps
- 7z
- zip
- rar
NOTES:
The dropped Decrypt All Files {random characters}.txt contains the following ransom message:
It sets the system's desktop wallpaper to the following image:
It appends the extension .{7 random characters} to the encrypted files.
It displays the following ransom message:
It asks for users to connect to the given URLs to pay and retrieve the key for decryption.
SOLUTION
9.700
11.340.04
12 Dec 2014
11.341.00
13 Dec 2014
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
Scan your computer with your Trend Micro product and note files detected as TROJ_CRYPCTB.J
Step 4
Restart in Safe Mode
Step 5
Search and delete this file
- %User Profile%\My Documents\Decrypt All Files {random characters}.bmp
- %User Profile%\My Documents\Decrypt All Files {random characters}.txt
- %User Profil%\My Documents\{random characters}.html
- %Windows%\Tasks\{random filename}.job
Step 6
Restore these modified registry values
Important:Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator's help. You may also check out this Microsoft article first before modifying your computer's registry.
- In HKEY_CURRENT_USER\Control Panel\Desktop
- From: Wallpaper = "%User Profile%\My Documents\Decrypt All Files {random characters}.bmp"
To: Wallpaper = "{user-defined}"
- From: Wallpaper = "%User Profile%\My Documents\Decrypt All Files {random characters}.bmp"
Step 7
Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_CRYPCTB.J. 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.
NOTES:
Restore the encrypted files from backup.
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