TROJ_CRYPTWALL.E
Ransom:Win32/Crowti (Microsoft); Generic.so (McAfee); Trojan.Cryptodefense (Symantec); Trojan.Win32.Agentb.bgtm (Kaspersky); Troj/Ransom-AMI (Sophos); Trojan.Win32.Generic!BT (Sunbelt); Trojan:W32/Injector.BF (FSecure); Trojan horse Crypt3.AUXC (AVG)
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 itself after execution.
TECHNICAL DETAILS
336,145 bytes
EXE
Yes
21 Oct 2014
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.
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
f3847c = "%System Root%\f3847cd\f3847cd.exe"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
f3847cd = "%User Profile%\Application Data\f3847cd.exe"
Other System Modifications
This Trojan modifies the following registry entries:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\SystemRestore
DisableSR = "1"
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Eventlog\Application\
ESENT
EventMessageFile = "%System%\ESENT.dll"
(Note: The default value data of the said registry entry is {random values}.)
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Eventlog\Application\
ESENT
CategoryMessageFile = "%System%\ESENT.dll"
(Note: The default value data of the said registry entry is {random values}.)
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Eventlog\Application\
ESENT
CategoryCount = "1"
(Note: The default value data of the said registry entry is 10.)
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Eventlog\Application\
ESENT
TypesSupported = "7"
(Note: The default value data of the said registry entry is 7.)
Dropping Routine
This Trojan drops the following files:
- %System Root%\f3847cd\f3847cd.exe
- %User Profile%\Application Data\f3847cd.exe
- %User Startup%\f3847cd.exe
- %User Startup%\f3847cd.exe:1
- %User Profile%\Application Data\f3847cd.exe:1
- %System Root%\f3847cd\f3847cd.exe:1
(Note: %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.. %User Profile% is a user's profile folder, where it usually is C:\Documents and Settings\{user name} on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name} 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 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.)
Other Details
This Trojan connects to the following possibly malicious URL:
- http://www.{BLOCKED}e.be/s5eroewr
- {BLOCKED}.165.200
- {BLOCKED}0.1
- {BLOCKED}21.38
- {BLOCKED}9.206.212
- {BLOCKED}.193.9
- {BLOCKED}1.69.61
- {BLOCKED}.100.227
- {BLOCKED}.113.228
It deletes itself after execution.
This report is generated via an automated analysis system.
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
Restart in Safe Mode
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
- f3847c = "%System Root%\f3847cd\f3847cd.exe"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
- f3847cd = "%User Profile%\Application Data\f3847cd.exe"
Step 4
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
- DisableSR = "1"
- In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Eventlog\Application\ESENT
- From: EventMessageFile = "%System%\ESENT.dll"
To: EventMessageFile = ""{random values}""
- From: EventMessageFile = "%System%\ESENT.dll"
- In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Eventlog\Application\ESENT
- From: CategoryMessageFile = "%System%\ESENT.dll"
To: CategoryMessageFile = ""{random values}""
- From: CategoryMessageFile = "%System%\ESENT.dll"
- In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Eventlog\Application\ESENT
- From: CategoryCount = "1"
To: CategoryCount = ""10""
- From: CategoryCount = "1"
- In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Eventlog\Application\ESENT
- From: TypesSupported = "7"
To: TypesSupported = ""7""
- From: TypesSupported = "7"
Step 5
Search and delete these components
- %System Root%\f3847cd\f3847cd.exe
- %User Profile%\Application Data\f3847cd.exe
- %User Startup%\f3847cd.exe
- %User Startup%\f3847cd.exe:1
- %User Profile%\Application Data\f3847cd.exe:1
- %System Root%\f3847cd\f3847cd.exe:1
Step 6
Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_CRYPTWALL.E. 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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