TROJ_CRYPTROLF.YMX
Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)
![](/vinfo/imgFiles/legend.jpg)
Threat Type: Trojan
Destructiveness: No
Encrypted: Yes
In the wild: Yes
OVERVIEW
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
3,776,512 bytes
EXE
No
17 Jun 2014
Displays graphics/image
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:
- %AppDataLocal%\winrar.exe
(Note: %AppDataLocal% is the Application Data folder found in Local Settings, where it is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local 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 creates the following folders:
- %All Users Profile%\Application Data\TEMP - Windows XP
- %All Users Profile%\TEMP - Windows 7 and Vista
(Note: %All Users Profile% is the All Users folder, where it usually is C:\Documents and Settings\All Users on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\ProgramData 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 adds the following registry entries to enable its automatic execution at every system startup:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
winrar = "%AppDataLocal%\winrar.exe"
Other System Modifications
This Trojan adds the following registry keys:
HKEY_CURRENT_USER\Software\Licenses
It adds the following registry entries:
HKEY_CURRENT_USER\Software\Licenses
{R7C0DB872A3F777C0} = "{random values}"
HKEY_CURRENT_USER\Software\Licenses
{K7C0DB872A3F777C0} = "{random values}"
HKEY_CURRENT_USER\Software\Licenses
{I7B4ED451FFFFFFFF} = "{random values}"
HKEY_CURRENT_USER\Software\Licenses
{07B4ED451FFFFFFFF} = "{random values}"
HKEY_CURRENT_USER\Software
winrar = "{value which indicates its installation}"
It changes the desktop wallpaper by modifying the following registry entries:
HKEY_CURRENT_USER\Control Panel\Desktop
Wallpaper = "%User Profile%\My Documents\ttt.jpg"
(Note: The default value data of the said registry entry is {previous user wallpaper}.)
HKEY_CURRENT_USER\Control Panel\Desktop
TileWallpaper = "0"
(Note: The default value data of the said registry entry is {previous user value}.)
Dropping Routine
This Trojan drops the following files:
- %AppDataLocal%\winrar.rar - contains the list of files to encrypt
- %User Profile%\My Documents\ttt.jpg - wallpaper to be set after encryption
- {malware path}\mmm.bat -it deletes the initial copy of this malware.
(Note: %AppDataLocal% is the Application Data folder found in Local Settings, where it is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local 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.. %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.)
Other Details
This Trojan encrypts files with the following extensions:
- 1cd
- 3gp
- 7z
- dbf
- doc
- docx
- dot
- dpr
- eml
- iso
- jpeg
- jpg
- mp4
- pot
- pps
- ppsx
- pptx
- rar
- rtf
- xls
- xlsx
- zip
NOTES:
This Trojan replaces some file binaries and the original is encrypted and appending on the same file. It targets to encrypt files from drives C to Z. After encrypting files, It displays the following on the desktop:
SOLUTION
9.700
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
Delete this registry key
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\Software
- Licenses
- Licenses
Step 3
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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
- winrar = "%AppDataLocal%\winrar.exe"
- winrar = "%AppDataLocal%\winrar.exe"
- In HKEY_CURRENT_USER\Software
- winrar = "{value which indicates its installation 1~3}"
- winrar = "{value which indicates its installation 1~3}"
Step 4
Reset your Desktop properties
Step 5
Search and delete this folder
- %All Users Profile%\Application Data\TEMP
- %All Users Profile%\TEMP
Step 6
Search and delete these files
- %AppDataLocal%\winrar.rar
- %User Profile%\My Documents\ttt.jpg
- {malware path}\mmm.bat
Step 7
Scan your computer with your Trend Micro product to delete files detected as TROJ_CRYPTROLF.YMX. 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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