TROJ_CRYPLOCK.IA
Luhe.Fiha.A(AVG), Trojan-Ransom.Win32.Crypren.qce (Kaspersky), Trojan.Cryptolocker.F(Symantec)
Windows
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.
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:
- %Windows%\{Random File Name 1}.exe
(Note: %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.)
It creates the following folders:
- %All Users Profile%\Application Data\{Random Folder Name 1}
(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
{Random Value 1} = "%Windows%\{Random File Name 1}.exe"
Other System Modifications
This Trojan adds the following registry keys:
HKEY_CURRENT_USER\Software\{Random Key 1}
It adds the following registry entries:
HKEY_CURRENT_USER\Software\{Random Key 1}
01000000 = "{random values}"
HKEY_CURRENT_USER\Software\{Random Key 1}
02000000 = "{random values}"
HKEY_CURRENT_USER\Software\{Random Key 1}
00000000 = "{random values}"
HKEY_CURRENT_USER\Software\{Random Key 1}
03000000 = "{random values}"
HKEY_CURRENT_USER\Software\{Random Key 1}
04000000 = "{random values}"
Dropping Routine
This Trojan drops the following files:
- %All Users Profile%\Application Data\{Random Folder Name 1}\01000000
- %All Users Profile%\Application Data\{Random Folder Name 1}\02000000
- %All Users Profile%\Application Data\{Random Folder Name 1}\00000000
- %All Users Profile%\Application Data\{Random Folder Name 1}\03000000
(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.)
Other Details
This Trojan connects to the following possibly malicious URL:
- http://{BLOCKED}tic.ru
It renames encrypted files using the following names:
- {original file name and extension}.encrypted
NOTES:
It drops DECRYPT_INSTRUCTIONS.html files on locations where it is able to encrypt files.
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 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. Before you could do this, you must restart in Safe Mode. For instructions on how to do this, you may refer to this page If the preceding step requires you to restart in safe mode, you may proceed to edit the system registry.
- In HKEY_CURRENT_USER\Software
- {Random Key 1}
- {Random Key 1}
Step 5
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
- {Random Value 1} = "%Windows%\{Random File Name 1}.exe"
- {Random Value 1} = "%Windows%\{Random File Name 1}.exe"
Step 6
Search and delete this folder
- %All Users Profile%\Application Data\{Random Folder Name 1}
Step 7
Search and delete these files
- DECRYPT_INSTRUCTIONS.html
Step 8
Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_CRYPLOCK.IA. 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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