Worm:Win32/Neeris.gen!C is the generic detection for a member of the Win32/Neeris family of worms. These worms spread via MNS Messenger and may contain backdoor functionalities. New variants of this worm may exploit a vulnerability in the Windows Server Service (srvsvc) in computers that have not yet applied
Microsoft Security Bulletin MS08-067.
You may be informed by your MSN Messenger contacts that your account has attempted or is attempting to send them a ZIP archive, or you may notice an unknown TFTP transaction in your logs.
Due to the generic nature of this detection, there are no common symptoms associated with this threat. Alert notifications from installed antivirus software may be the only symptom(s).
Worm:Win32/Neeris.gen!C is the generic detection for a member of the Win32/Neeris family of worms. These worms spread via MNS Messenger and may contain backdoor functionalities. New variants of this worm may exploit a vulnerability in the Windows Server Service (srvsvc) in computers that have not yet applied
Microsoft Security Bulletin MS08-067.
Installation
Different samples of Win32/Neeris.gen!C install themselves in systems in varying ways. They commonly copy themselves in the Windows or Windows system folder and modify the system registry so that they run every time Windows starts.
For example, one variant of this family copies itself to a subfolder of the Windows folder as VMwareService.exe and makes the following registry autostart modification:
Adds value: "GON"
With data: "%windir%\system\VMwareService.exe"
To subkey: HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Shell Extensions
Another variant of this worm may copy itself as the following file
%windir%\system\netmon.exe
The worm may be present as a file with a two digit name and .SCR extension such as 21.scr.
The registry is modified to run the dropped worm copy at each Windows start. Other registry data may be created to execute the worm when booting in Windows safe mode.
Adds value: "netmon"
With data: "%windir%\system\netmon.exe"
To subkey: HKLM\Software\Microsoft\Windows\CurrentVersion\Run
Adds value: "(default)"
With data: "service"
To subkey: HKLM\SYSTEM\ControlSet001\Control\SafeBoot\Minimal\netmon32
Adds value: "(default)"
With data: "service"
To subkey: HKLM\SYSTEM\ControlSet001\Control\SafeBoot\Network\netmon32
Spreads Via...
MSN Messenger
Win32/Neeris.gen!C spreads by sending a copy of itself to all of a user's contacts in MSN Messenger. The attached copy is usually a ZIP archive containing the EXE copy of the worm.
Removable Drives
This worm may also drop a copy of itself and a corresponding autorun.inf file into all available removable drives. The function of the autorun.inf file is to ensure that the worm copy automatically runs when the drive is accessed and Autoplay is enabled. The image below illustrates how a user could potentially launch the worm when accessing an infected share:
Filenames of the dropped worm copy vary but may have a name such as 'smartkey.exe'.
SQL Servers with Weak Passwords
This worm may also attempt to connect to SQL servers by attempting to log in using commonly-used passwords. Once connected, it may instruct the server to download and run a copy of itself via TFTP.
Microsoft Server Service Vulnerability - MS06-040
This worm may also send malformed packets to exploit a known vulnerability in the Server Service discussed in Microsoft Security Advisory
MS06-040. Once connected to vulnerable computers, it may download and execute a copy of itself.
Microsoft Server Service Vulnerability - MS08-067
This worm may open a random high numbered TCP port such as 16349 or 30379. The worm then attempts to connect with computers across a network using TCP port 445 to exploit a known vulnerability in the Server Service discussed in Microsoft Security Bulletin
MS08-067.
Once connected to vulnerable computers, it may instruct the compromised computer to download and execute a copy of the worm using the opened TCP port (such as 16349 or 30379). The worm copy is downloaded using HTTP (TCP port 80).
Payload
Bypass Windows Firewall
This worm may add itself as an "authorized application" by modifying the Windows firewall policy stored in the registry.
Adds value: "%windir%\system\netmon.exe"
With data: "%windir%\system\netmon.exe:*:microsoft enabled"
To subkey: HKLM\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\List
Backdoor Functionality
Win32/Neeris.gen!C may connect to a predefined Internet Relay Channel (IRC) server using a specified port number such as TCP port 6667 or 449. Once connected, it awaits commands from a remote attacker.
Removes Connection Restrictions
Win32/Neeris.gen!C may drop a driver '<system folder>\drivers\sysdrv32.sys' which patches TCP/IP to remove connection throttling in Windows XP SP2 computers.
Analysis by Jireh Sanico
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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Protect yourself against social engineering attacks.
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
Most antivirus software can detect and prevent infection by known malicious software. To help protect you from infection, you should always run antivirus software that is updated with the latest signature files. Antivirus software is available from several sources. For more information,
see http://www.microsoft.com/protect/computer/viruses/vista.mspx.
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 or are 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. please see our article '
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, please see our article '
What is social engineering?'.
