Worm:Win32/Nuqel.BI is a worm - a self-propagating program that can spread itself from one computer to another. Worms may spread themselves via a variety of different channels in order to compromise new computers. Commonly, worms may spread directly by copying themselves to removable or network drives, or by attempting to exploit particular vulnerabilities on targeted computers. Worms also often attempt to spread via platforms that require user interaction in order to run. They may send themselves as an attachment to an email or an instant message, or send a link to a copy of themselves in the body of a message. In these cases the message needs to be convincing enough to encourage the victim to click on the link or attachment and run or download a copy of the worm.
Installation
When executed, Worm:Win32/Nuqel.BI copies itself to the following locations:
- %windir%\hinhem.scr
- %windir%\scvshosts.exe
- <system folder>\blastclnnn.exe
- <system folder>\scvshosts.exe
Note: <system folder> refers to a variable location that is determined by the malware by querying the Operating System. The default installation location for the System folder for Windows 2000 and NT is C:\Winnt\System32; and for XP, Vista, and 7 is C:\Windows\System32.
The malware modifies the following registry entries to ensure that its copy executes at each Windows start:
Adds value: "Yahoo Messengger"
With data: "c:\windows\system32\scvshosts.exe"
To subkey: HKCU\Software\Microsoft\windows\currentversion\run
Adds value: "Shell"
With data: "explorer.exe scvshosts.exe"
To subkey: HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
The malware creates the following files on an affected computer:
The malware attempts to create a scheduled Windows task that runs the worm at 09:00 am every day of the week, by running the following Windows shell command instruction:
cmd.exe /C AT /delete /yes
cmd.exe /C AT 09:00 /interactive /EVERY:m,t,w,th,f,s,su <system folder>\blastclnnn.exe
Payload
Modifies system settings
Worm:Win32/Nuqel.BI modifies the affected computer system's settings by making the following changes to the registry:
- The malware disables the system utility Task Manager by making the following registry modification:
Adds value: "DisableTaskMgr"
With data: "1"
To subkey: HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\System
- The malware ensures that Internet Explorer starts in online mode by making the following registry modification:
Adds value: "GlobalUserOffline"
With data: "0"
To subkey: HKCU\Software\Microsoft\Windows\CurrentVersion\Internet Settings
- The malware removes the Folder Options item from all Explorer menus and the Control Panel by making the following registry modification:
Adds value: "NoFolderOptions"
With data: "1"
To subkey: HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\Explorer
Note: Removing access to these options may hinder the affected user's ability to detect and remove malware.
- The malware overrides the defined timeout period/value, resulting in scheduled tasks not being stopped after a timeout period; it does this by making the following registry modification:
Adds value: "AtTaskMaxHours"
With data: "0"
To subkey: HKLM\SYSTEM\CurrentControlSet\Services\Schedule
Contacts remote hosts
The malware may contact the following remote hosts using port 80:
- setting3.9999mb.com
- setting3.yeahost.com
- www.freewebs.com
Commonly, malware may contact a remote host for the following purposes:
- To confirm Internet connectivity
- To report a new infection to its author
- To receive configuration or other data
- To download and execute arbitrary files (including updates or additional malware)
- To receive instruction from a remote attacker
- To upload data taken from the affected computer
This malware description was produced and published using our automated analysis system's examination of file SHA1 1f75804af2d6457ae9a351479eb1d735575145fd.