Worm:Win32/Neeris.BF

Worm:Win32/Neeris.BF is a member of Win32/Neeris - a family of worms that spreads via Messenger and contains backdoor functionality that allows unauthorized access and control of an affected computer. Some variants of this family may also spread via removable drives or by exploiting particular vulnerabilities.

When executed, Worm:Win32/Neeris.BF copies itself to c:\documents and settings\administrator\local settings\temp\avntsc.exe.

The malware modifies the following registry entries to ensure that its copy executes at each Windows start:

Adds value: "Microsoft iexplorer11"
With data: "c:\documents and settings\administrator\local settings\temp\avntsc.exe"
To subkey: HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run

Adds value: "Microsoft iexplorer11"
With data: "c:\documents and settings\administrator\local settings\temp\avntsc.exe"
To subkey: HKCU\Software\Microsoft\windows\currentversion\run

The malware creates the following files on an affected computer:

Variants of the Win32/Neeris family may use a number of different methods in order to spread to other computers.

Windows Live Messenger

Win32/Neeris spreads via Microsoft Messenger. It uses messages in a number of different languages in order to spread to as many users as possible. It may check the specified locale of the affected computer in order to send messages in the appropriate language. It sends a message to all of the infected user's contacts with a copy of itself as an attachment.

Vulnerability exploit

Win32/Neeris may attempt to spread by attempting to exploit a number of different vulnerabilities that affects Windows or other third party software. The list of vulnerabilities that may be targeted in this manner is variable, however, examples include the vulnerabilities discussed in the following security bulletins:

Neeris may also attempt to target computers running Microsoft SQL. It attempts to log on to these computers by exploiting weak passwords utilizing a list of passwords and usernames that it carries in its code.

Removable drives

Worm:Win32/Neeris.BF copies itself to the following locations on removable drives:

• <targeted drive>:\avm0\avm0\avm0o0.exe

It also places an autorun.inf file in the root directory of the targeted drive. Such autorun.inf files contain execution instructions for the operating system, so that when the removable drive is accessed from another computer supporting the Autorun feature, the malware is launched automatically.

Note: This worm was observed to write an executable and create an autorun.inf file on a targeted drive in our automated testing environment. This is particularly common malware behavior, generally utilized in order to spread malware from computer to computer.

It should also be noted that autorun.inf files on their own are not necessarily a sign of infection, as they are used by legitimate programs and installation CDs.

The malware may also create the following files on targeted drives when spreading:

• <targeted drive>:\avm0\avm0\desktop.ini

Allows backdoor access and control

Worm:Win32/Neeris.BF attempts to connect to an IRC server at avx2.botsgod.info via TCP port 4949, join a channel and wait for commands. Using this backdoor, an attacker can perform a number of actions on an affected computer. For example, an attacker may be able to perform the following actions:

• Download and execute arbitrary files
• Upload files
• Spread to other computers using various methods of propagation
• Log keystrokes or steal sensitive data
• Modify system settings
• Run or terminate applications
• Delete files

This malware description was produced and published using our automated analysis system's examination of file SHA1 425f5f59122325bf4be9faad54776cd25ba396ef.