TROJ_CRYPTESLA.J
Ransom:Win32/Tescrypt.A (Microsoft); Win32/Filecoder.EM (ESET-NOD32); Trojan.Win32.Filecoder (Ikarus)
Windows
![](/vinfo/imgFiles/legend.jpg)
Threat Type: Trojan
Destructiveness: No
Encrypted:
In the wild: Yes
OVERVIEW
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 deletes the initially executed copy of itself.
TECHNICAL DETAILS
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 copies of itself into the affected system and executes them:
- %Application Data%\{Random 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.)
It drops the following files:
- %Application Data%\log.html
- %Desktop%\HELP_TO_SAVE_YOUR_FILES.bmp
- %Desktop%\HELP_TO_SAVE_YOUR_FILES.txt
- %Desktop%\CryptoLocker.lnk
- %Application Data%\key.dat
(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.. %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.)
Autostart Technique
This Trojan adds the following registry entries to enable its automatic execution at every system startup:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
svv_e = "%Application Data%\{Random Filename}.exe"
Other System Modifications
This Trojan modifies the following registry entries:
HKEY_CURRENT_USER\Control Panel\Desktop
WallpaperStyle = "0"
(Note: The default value data of the said registry entry is {User Preferences}.)
HKEY_CURRENT_USER\Control Panel\Desktop
TileWallpaper = "0"
(Note: The default value data of the said registry entry is {User Preferences}.)
HKEY_CURRENT_USER\Control Panel\Desktop
Wallpaper = "%Desktop%\HELP_TO_SAVE_YOUR_FILES.bmp"
(Note: The default value data of the said registry entry is {User Preferences}.)
Other Details
This Trojan connects to the following URL(s) to get the affected system's IP address:
- http://ipinfo.io/ip
It connects to the following possibly malicious URL:
- http://{BLOCKED}7vlep5o.42kdb12.net/state1.php?
- http://{BLOCKED}7vlep5o.42kjb11.net/state1.php?
- http://{BLOCKED}7vlep5o.tor2web.blutmagie.de:443
- http://{BLOCKED}7vlep5o.tor2web.fi:443
It renames encrypted files using the following names:
- {original filename}.ecc
It does the following:
- This Trojan encrypts the infected machine's personal files and demands payment for decryption service.
It deletes the initially executed copy of itself
SOLUTION
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
Step 4
Delete this registry value
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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
- svv_e = "%Application Data%\{Random Filename}.exe"
- svv_e = "%Application Data%\{Random Filename}.exe"
Step 5
Search and delete this file
- %Application Data%\key.dat
- %Application Data%\log.html
- %Desktop%\HELP_TO_SAVE_YOUR_FILES.bmp
- %Desktop%\HELP_TO_SAVE_YOUR_FILES.txt
- %Desktop%\CryptoLocker.lnk
Step 6
Restore this modified registry value
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
- From: WallpaperStyle = "0"
To: WallpaperStyle = {User Preferences}
- From: WallpaperStyle = "0"
- In HKEY_CURRENT_USER\Control Panel\Desktop
- From: TileWallpaper = "0"
To: TileWallpaper = {User Preferences}
- From: TileWallpaper = "0"
- In HKEY_CURRENT_USER\Control Panel\Desktop
- From: Wallpaper = "%Desktop%\HELP_TO_SAVE_YOUR_FILES.bmp"
To: Wallpaper = {User Preferences}
- From: Wallpaper = "%Desktop%\HELP_TO_SAVE_YOUR_FILES.bmp"
Step 7
Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_CRYPTESLA.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.
Step 8
Scan your computer with your Trend Micro product to delete files detected as TROJ_CRYPTESLA.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.
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