TROJ_RANSOM.CTD
Trojan:Win32/LockScreen.CV (Microsoft)
Windows 2000, Windows XP, Windows Server 2003
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
503,516 bytes
EXE
Yes
04 Feb 2013
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:
- %User Profile%\Application Data\1.exe
(Note: %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.)
Autostart Technique
This Trojan modifies the following registry entries to ensure it automatic execution at every system startup:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Shell = "%User Profile%\Application Data\1.exe"
(Note: The default value data of the said registry entry is Explorer.exe.)
Other System Modifications
This Trojan adds the following registry keys:
HKEY_LOCAL_MACHINE\Software\Policies\
Microsoft\Internet Explorer\Restrictions
HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Policies\
Explorer
It adds the following registry entries:
HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\Internet Explorer\Restrictions
NoBrowserContextMenu = "1"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\policies\
Explorer
NoViewContextMenu = "1"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\policies\
system
EnableLUA = "0"
It modifies the following registry entries:
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot
AlternateShell = "%User Profile%\Application Data\1.exe"
(Note: The default value data of the said registry entry is cmd.exe.)
Dropping Routine
This Trojan drops the following files:
- %User Temp%\aut1.tmp
- %User Temp%\qyovzpi
- %User Startup%\ja.lnk
- %User Temp%\aut2.tmp
- %User Temp%\gtofspg
(Note: %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.. %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.)
This report is generated via an automated analysis system.
SOLUTION
9.300
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
Identify and delete files detected as TROJ_RANSOM.CTD using either the Startup Disk or Recovery Console
Step 3
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_LOCAL_MACHINE\Software\Policies\Microsoft\Internet Explorer
- Restrictions
- In HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Policies
- Explorer
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\Policies\Microsoft\Internet Explorer\Restrictions
- NoBrowserContextMenu = "1"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\Explorer
- NoViewContextMenu = "1"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\system
- EnableLUA = "0"
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\SYSTEM\ControlSet001\Control\SafeBoot
- From: AlternateShell = "%User Profile%\Application Data\1.exe"
To: AlternateShell = ""cmd.exe""
- From: AlternateShell = "%User Profile%\Application Data\1.exe"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
- From: Shell = "%User Profile%\Application Data\1.exe"
To: Shell = ""Explorer.exe""
- From: Shell = "%User Profile%\Application Data\1.exe"
Step 6
Search and delete these components
- %User Temp%\aut1.tmp
- %User Temp%\qyovzpi
- %User Startup%\ja.lnk
- %User Temp%\aut2.tmp
- %User Temp%\gtofspg
Step 7
Scan your computer with your Trend Micro product to delete files detected as TROJ_RANSOM.CTD. 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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