W32.Nohoper.7397

When a file that is infected with W32.Nohoper.7397 runs, it does the following:

It appends the viral body to the last section of C:\%windir%\Notepad.exe and changes the entry point to the viral body. The length of the infected file increases by 8,192 bytes. The file then copies the infected Notepad.exe file as C:\Freeporn.exe.pif.

It randomly chooses 20 PE files in the C:\%system% folder and appends the viral body to the last section of each of these files. It changes the entry point of the infected file to the viral body. The length of the infected file increases by 8,192 bytes.

NOTES:

• %windir% is a variable. The virus locates the \Windows folder (by default this is C:\Windows or C:\Winnt) and infects Notepad.exe file in that folder.
• %system% is a variable. The virus locates the \Windows\System folder (by default this is C:\Windows\System or C:\Winnt\System32) and infects files in that folder.
• The date and time stamp of all infected files are changed to the current system date and time.
• The virus does not reinfect any files.
• If C:\Freeporn.exe.pif already exists, the virus does not overwrite it.

If mIRC is installed on the infected system, the virus creates Mirc.ini so that the infected C:\Freeporn.exe.pif file is sent to other mIRC users.

The virus creates the file C:\Hemp.htm, and opens it in Internet Explorer.exe. The open Internet Explorer window has the following characteristics:

Title: -=Win32.HempHoper=- (c) by Necronomikon [Zerogravity]
Text:
Necronomikons
Virusinformation

When C:\Hemp.htm is opened, it does the following:

It sends an email message to a predefined email address. The subject line of the message is "Network Info," and its message body contains the name of the infected computer.

It also uses Microsoft Outlook to send an infected file to all contacts in the Outlook Address Book. The message has the following characteristics,
Subject: Some freeporn
Message: Here is the file you asked for...
Attachment: Freeporn.exe.pif

C:\Hemp.htm then attempts to copy itself as C:\%windir%\Win.vbs.

It searches for a file named Drop.exe in the C:\%windir%\ folder and in the download folder for Internet Explorer. If it cannot find this file, it attempts to download into the C:\%windir% folder a file named Drop.exe from a Web site that is predefined by the virus.

When Drop.exe runs, it displays this message:
Title: *Win32.HempHoper* (c) by Necronomikon/[ Zer0Gravity]
Text: Damn i am stoned...!;o)

Drop.exe does not contain any other harmful payload.

Recommendations

Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":

• Use a firewall to block all incoming connections from the Internet to services that should not be publicly available. By default, you should deny all incoming connections and only allow services you explicitly want to offer to the outside world.
• Enforce a password policy. Complex passwords make it difficult to crack password files on compromised computers. This helps to prevent or limit damage when a computer is compromised.
• Ensure that programs and users of the computer use the lowest level of privileges necessary to complete a task. When prompted for a root or UAC password, ensure that the program asking for administration-level access is a legitimate application.
• Disable AutoPlay to prevent the automatic launching of executable files on network and removable drives, and disconnect the drives when not required. If write access is not required, enable read-only mode if the option is available.
• Turn off file sharing if not needed. If file sharing is required, use ACLs and password protection to limit access. Disable anonymous access to shared folders. Grant access only to user accounts with strong passwords to folders that must be shared.
• Turn off and remove unnecessary services. By default, many operating systems install auxiliary services that are not critical. These services are avenues of attack. If they are removed, threats have less avenues of attack.
• If a threat exploits one or more network services, disable, or block access to, those services until a patch is applied.
• Always keep your patch levels up-to-date, especially on computers that host public services and are accessible through the firewall, such as HTTP, FTP, mail, and DNS services.
• Configure your email server to block or remove email that contains file attachments that are commonly used to spread threats, such as .vbs, .bat, .exe, .pif and .scr files.
• Isolate compromised computers quickly to prevent threats from spreading further. Perform a forensic analysis and restore the computers using trusted media.
• Train employees not to open attachments unless they are expecting them. Also, do not execute software that is downloaded from the Internet unless it has been scanned for viruses. Simply visiting a compromised Web site can cause infection if certain browser vulnerabilities are not patched.
• If Bluetooth is not required for mobile devices, it should be turned off. If you require its use, ensure that the device's visibility is set to "Hidden" so that it cannot be scanned by other Bluetooth devices. If device pairing must be used, ensure that all devices are set to "Unauthorized", requiring authorization for each connection request. Do not accept applications that are unsigned or sent from unknown sources.
• For further information on the terms used in this document, please refer to the Security Response glossary.

Summary