W32.IRCBot.B

The Trojan may arrive in an email with the following characteristics:

From: updates@symantec.com (spoofed email address)
Subject: Last Update.
Message: October 06, 2003
Intruder Alert 4.1 W32_Webb_Worm Policy
This policy detects the propagation of the W32.SobigF.Worm though changes in the registry.

W32.Webb.F@mm is a mass-mailing, network-aware worm that sends itself to all the email addresses it finds in various files.
The worm uses its own SMTP engine to propagate and attempts to create a copy of itself on accessible network shares, but fails due to bugs in the code.

In attachment you can find program that update your Norton Antivirus to Norton Antivirus 2004.

Attachment: nav32.zip

The attached zip file contains the following file:
nav32.exe

Note: The email message references a fake program update for Norton AntiVirus. The sender, updates@symantec.com, is a spoofed email address. Symantec never sends unsolicited email; the attachment should be deleted.

Once executed, the Trojan creates the following file:
%System%\RPC[RANDOM CHARACTERS].exe

The Trojan creates the following registry entries, so that it runs every time Windows starts:

• HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run\"windowsupdate" = "RPC[RANDOM CHARACTERS].exe"
• HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\RunServices\"windowsupdate" = "RPC[RANDOM CHARACTERS].exe"

It opens a back door on the compromised computer that connects to a predetermined IRC channel on the IRC server itc.ourmoney.pp.ruz using TCP port 31337 that allows unauthorized access to perform the following actions:

• May copy itself to shared folders on other computers
• Monitor network communications
• Download and execute files, some of which may include an updated version of the Trojan
• May copy itself to other IRC channels
• Participate in denial of service attacks against a target specified by the remote attacker
• Deletes itself
• Disable processes, some of which may be security-related
• Visit URLs

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