Trojan:Win32/Ramtopt.A is a trojan that encrypts files on the local computer.
System changes
The following system changes may indicate the presence of this malware:
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The presence of the following files:
%UserProfile%\My Documents\regdtopt.exe
%UserProfile%\Desktop\regdtopt.exe
%AppData%\Identities\regdtopt.exe
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The presence of the following registry modifications:
Adds value: "Optim1"
With data: "regdtopt.exe"
Adds value: "Optim2"
With data: "%UserProfile%\My Documents\regdtopt.exe"
Adds value: "Optim3"
With data: "%AppData%\Identities\regdtopt.exe"
Adds value: "Optim4"
With data: "%UserProfile%\Desktop\regdtopt.exe"
Adds value: "Optim5"
To subkey: HKCU\Software\Microsoft\Windows\CurrentVersion\Run
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The display of the error messages such as the following:
liCrypt: A problem occured, Please Restart Windows
Trojan:Win32/Ramtopt.A is a trojan that encrypts files on the local computer.
Installation
This trojan may be present as the following:
%UserProfile%\My Documents\regdtopt.exe
%UserProfile%\Desktop\regdtopt.exe
%AppData%\Identities\regdtopt.exe
<local linked folder>\regdtopt.exe
where "<local linked folder>" is a folder shortcut found in the above mentioned folders. The registry may be modified to run the trojan at each Windows start.
Adds value: "Optim1"
With data: "regdtopt.exe"
Adds value: "Optim2"
With data: "%UserProfile%\My Documents\regdtopt.exe"
Adds value: "Optim3"
With data: "%AppData%\Identities\regdtopt.exe"
Adds value: "Optim4"
With data: "%UserProfile%\Desktop\regdtopt.exe"
Adds value: "Optim5"
With data: "<local linked folder>\regdtopt.exe"
To subkey: HKCU\Software\Microsoft\Windows\CurrentVersion\Run
Payload
Encrypts local files
When the trojan runs, it verifies if its currently running file name is "regdtopt.exe". If it is not, the trojan ends execution. If the file name is equal to "regdtopt.exe", it then checks if any link or shortcut files are stored in the folder "%UserProfile%\Recent". For each shortcut or link found, the trojan follows the link and renames the original file extension as "<original file name>.viCrypt" and also encrypts the file.
In some cases, the extension is renamed to ".liCrypt". The trojan renames all files found in the following folders:
%UserProfile%\My Documents\
%UserProfile%\Desktop\
%UserProfile%\Application Data\Identities\
<local linked folder>\
where "<local linked folder>" is a folder shortcut found in the above mentioned folders. Files found are renamed as "<orignal file name>.viCrypt". The trojan encrypts all renamed files.
Displays error messages
As a result of encrypting files, Windows may fail to run or open requested files. Error messages could display text resembling the following:
liCrypt: A problem occured, Please Restart Windows
Analysis by Tim Liu
Take the following steps to help prevent infection on your system:
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Enable a firewall on your computer.
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Get the latest computer updates for all your installed software.
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Use up-to-date antivirus software.
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Use caution when opening attachments and accepting file transfers.
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Use caution when clicking on links to web pages.
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Avoid downloading pirated software.
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Protect yourself against social engineering attacks.
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Use strong passwords.
Enable a firewall on your computer
Use a third-party firewall product or turn on the Microsoft Windows Internet Connection Firewall.
To turn on the Windows Firewall in Windows Vista
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Click Start, and click Control Panel.
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Click Security.
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Click Turn Windows Firewall on or off.
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Select On.
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Click OK.
To turn on the Internet Connection Firewall in Windows XP
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Click Start, and click Control Panel.
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Click Network and Internet Connections. If you do not see Network and Internet Connections, click Switch to Category View.
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Click Change Windows Firewall Settings.
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Select On.
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Click OK.
Get the latest computer updates
Updates help protect your computer from viruses, worms, and other threats as they are discovered. It is important to install updates for all the software that is installed in your computer. These are usually available from vendor websites.
You can use the Automatic Updates feature in Windows to automatically download future Microsoft security updates while your computer is on and connected to the Internet.
To turn on Automatic Updates in Windows Vista
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Click Start, and click Control Panel.
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Click System and Maintainance.
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Click Windows Updates.
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Select a setting. Microsoft recommends selecting Install updates automatically and choose a time that is convenient for you. If you do not choose Automatic, but you choose to be notified when updates are ready, a notification balloon appears when new downloads are available to install. Click the notification balloon to review and install the updates.
To turn on Automatic Updates in Windows XP
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Click Start, and click Control Panel.
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Click System.
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Click Automatic Updates.
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Select a setting. Microsoft recommends selecting Automatic. If you do not choose Automatic, but you choose to be notified when updates are ready, a notification balloon appears when new downloads are available to install. Click the notification balloon to review and install the updates.
Use up-to-date antivirus software
Use caution when opening attachments and accepting file transfers
Exercise caution with e-mail and attachments received from unknown sources, or received unexpectedly from known sources. Use extreme caution when accepting file transfers from known or unknown sources.
Use caution when clicking on links to Web pages
Exercise caution with links to web pages that you receive from unknown sources, especially if the links are to a Web page that you are not familiar with, unsure of the destination of, or suspicious of. Malicious software may be installed in your system simply by visiting a Web page with harmful content.
Avoid downloading pirated software
Threats may also be bundled with software and files that are available for download on various torrent sites. Downloading "cracked" or "pirated" software from these sites carries not only the risk of being infected with malware, but is also illegal. For more information, see '
The risks of obtaining and using pirated software'.
Protect yourself from social engineering attacks
While attackers may attempt to exploit vulnerabilities in hardware or software in order to compromise a system, they also attempt to exploit vulnerabilities in human behavior in order to do the same. When an attacker attempts to take advantage of human behavior in order to persuade the affected user to perform an action of the attacker's choice, it is known as 'social engineering'. Essentially, social engineering is an attack against the human interface of the targeted system. For more information, see '
What is social engineering?'.
Use strong passwords
Attackers may try to gain access to your Windows account by guessing your password. It is therefore important that you use a strong password – one that cannot be easily guessed by an attacker. A strong password is one that has at least 8 characters, and combines letters, numbers, and symbols. For more information, see
http://www.microsoft.com/protect/yourself/password/create.mspx.
Manual removal is not recommended for this threat. To detect and remove this threat and other malicious software that may have been installed, run a full-system scan with an up-to-date antivirus product such as
Microsoft Security Essentials, or the
Windows Live OneCare safety scanner. For more information about using antivirus software, see
http://www.microsoft.com/security/antivirus/av.aspx.
Trojan:Win32/Ramtopt.A may make lasting changes such as encrypting files and that will NOT be restored by detecting and removing this threat. In order to return an affected system to its pre-infected state, files encrypted by Trojan:Win32/Ramtopt.A must be restored from backup.
