How remove a Virus from a PC

Last Updated: 26/10/10

If you believe your computer has been compromised, follow the steps below to identify and remove the virus.

Note that this represents a "first effort" approach.If these methods do not succeed, your system will require a full rebuild.

Only use the tools recommended on this page when repairing a virus- if you do not succeed in removing the virus using these methods, contact IT Services for further assistance.

Step 1

WARNING: Current viruses harvest personal information from your computer. In the event of a virus on your computer, you should contact your online banking and credit card companies to have your accounts put on fraud alert, and change your password on all other internet accounts and social networking sites. Do this on a seperate computer.

Download and install Sophos Anti-Virus from UCD Connect. This is located in the "Software downloads" section on the main connect page. Staff and students may install Sophos on their own home computers in addition to laptops and UCD computers. The UCD Sophos build contains antispyware and removal toolkits, and is preconfigured for best results in the UCD environment.

NOTE: Remove all other antivirus software from your computer. If you have multiple antivirus packages installed, their effectiveness is reduced as they interfere with each other.

Step 2

If Sophos cannot find, or cannot remove the viruses, or if the message ‘Sophos Cannot delete these files because they are in use by the OS’ appears, note the file names and follow the instructions on setting up a boot device (USB stick or CD) to remove the virus below. You should also attempt to remove the virus using the Microsoft Malware Removal Tool- available below. (Microsoft MRT does not interfere with antivirus software). Details in the next step.

On a separate computer:

Download an emergency (bootable) copy of Sophos.
Download current virus updates.
Follow Sophos' instructions for removing viruses using this toolkit.

Step 3

The Microsoft malware removal tool download and instructions for use can be found here.

Scanning using this tool is effective for malware such as trojans and spyware. This software interoperates safely with Sophos, and can be left permanently on your computer. It updates using standard Microsoft update settings.

Step 4

If these steps are not effective, it is likely that your computer will require a rebuild. Back up your data to a CD, USB stick or external drive, and contact IT Services for further assistance.

Step 5

Contact IT Services help desk on ext. 2700 to find your nearest IT support centre.