TROJ_CROWTI.SM0
Ransom:Win32/Crowti (Microsoft), Trojan.Cryptodefense (Symantec), Ransom-O (McAfee), Trojan-Ransom.Win32.Cryptodef.bht (Kaspersky), Win32/Filecoder.NCE (ESET), W32/CRYPTWALL.B!tr (Fortinet)
Windows
Threat Type: Trojan
Destructiveness: No
Encrypted: Yes
In the wild: Yes
OVERVIEW
Dropped by other malware, 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.
It connects to certain websites to send and receive information.
TECHNICAL DETAILS
455,760 bytes
EXE
Yes
18 Sep 2014
Connects to URLs/IPs
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:
- %Application Data%\{random name}.exe
- %System Root%\{random name}\{random name}.exe
- %User Startup%\{random name}.exe
- %User Temp%\tmp684289.exe
(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista and 7.. %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.. %User Startup% is the current user's Startup folder, which is usually C:\Windows\Profiles\{user name}\Start Menu\Programs\Startup on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu\Programs\Startup on Windows NT, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup.. %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)
It creates the following folders:
- %System Root%\{random name}
(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)
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 name} = "%Application Data%\{random name}.exe"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{random name 2} = "%System Root%\{random name}\{random name}.exe"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
cmmon32 = "%User Temp%\tmp684289.exe B"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\RunOnce
*{random name} = "%Application Data%\{random name}.exe"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\RunOnce
*{random name 2} = "%System Root%\{random name}\{random name}.exe"
Other System Modifications
This Trojan adds the following registry keys:
HKEY_CURRENT_USER\Software\{random key}
It modifies the following registry entries:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\SystemRestore
DisableSR = "1"
(Note: The default value data of the said registry entry is "0".)
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\BITS
Start = "4"
(Note: The default value data of the said registry entry is "{default value}".)
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\ERSvc
Start = "4"
(Note: The default value data of the said registry entry is "{default value}".)
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\WerSvc
Start = "4"
(Note: The default value data of the said registry entry is "{default value}".)
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\WinDefend
Start = "4"
(Note: The default value data of the said registry entry is "{default value}".)
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\wscsvc
Start = "4"
(Note: The default value data of the said registry entry is "{default value}".)
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\wuauserv
Start = "4"
(Note: The default value data of the said registry entry is "{default value}".)
Other Details
This Trojan connects to the following website to send and receive information:
- http://{BLOCKED}dedwar.com
NOTES:
It encrypts files in the system. For folders where files are encrypted, it drops the following files:
- DECRYPT_INSTRUCTION.HTML
- DECRYPT_INSTRUCTION.TXT
- DECRYPT_INSTRUCTION.URL
SOLUTION
9.700
11.155.00
18 Sep 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
Restart in Safe Mode
Step 3
Search and delete this folder
- %System Root%\{random name}
Step 4
Delete these 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\Software\Microsoft\Windows\CurrentVersion\Run
- {random name} = "%Application Data%\{random name}.exe"
- {random name} = "%Application Data%\{random name}.exe"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
- {random name 2} = "%System Root%\{random name}\{random name}.exe"
- {random name 2} = "%System Root%\{random name}\{random name}.exe"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
- cmmon32 = "%User Temp%\tmp684289.exe B"
- cmmon32 = "%User Temp%\tmp684289.exe B"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\RunOnce
- *{random name} = "%Application Data%\{random name}.exe"
- *{random name} = "%Application Data%\{random name}.exe"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\RunOnce
- *{random name 2} = "%System Root%\{random name}\{random name}.exe"
- *{random name 2} = "%System Root%\{random name}\{random name}.exe"
Step 5
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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SystemRestore
- From: DisableSR = "1"
To: DisableSR = "0"
- From: DisableSR = "1"
- In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\BITS
- From: Start = "4"
To: Start = "{default value}"
- From: Start = "4"
- In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ERSvc
- From: Start = "4"
To: Start = "{default value}"
- From: Start = "4"
- In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\WerSvc
- From: Start = "4"
To: Start = "{default value}"
- From: Start = "4"
- In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\WinDefend
- From: Start = "4"
To: Start = "{default value}"
- From: Start = "4"
- In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\wscsvc
- From: Start = "4"
To: Start = "{default value}"
- From: Start = "4"
- In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\wuauserv
- From: Start = "4"
To: Start = "{default value}"
- From: Start = "4"
Step 6
Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_CROWTI.SM0. 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
The following created files/folders/registry keys/registry entries cannot be identified by the user since there are no reference values in the created key. The only way it can be identified is by comparing the present system information with a backup. Note that the said components do not have to be deleted since it won't be harmful to the system.
- In HKEY_CURRENT_USER\Software
- {random key}
- {random key}
Step 8
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.
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