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.

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

 

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).

 

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

Manual removal is not recommended for this threat. Use Microsoft Security Essentials or another up-to-date scanning and removal tool to detect and remove this threat and other unwanted software from your computer. For more information on Microsoft security products, see http://www.microsoft.com/protect/products/computer/default.mspx.