Monday, April 25, 2011

How to use ComboFix

SkyHi @ Monday, April 25, 2011
How to use ComboFix

Table of Contents
  1. Using ComboFix
  2. Forums to receive help analyzing ComboFix logs
  3. Manually installing the Windows Recovery Console
  4. Manually restoring the Internet connection
 
 
 ntroduction ComboFix is a program, created by sUBs, that scans your computer for known malware, and when found, attempts to clean these infections automatically. In addition to being able to remove a large amount of the most common and current malware, ComboFix also displays a report that can be used by trained helpers to remove malware that is not automatically removed by the program.
At this time ComboFix can only run on the following Windows versions:
  • Windows XP (32-bit only)
  • Windows 2000 (32-bit only)
  • Windows Vista (32-bit/64-bit)
  • Windows 7 (32-bit/64-bit)
You should not run ComboFix unless you are specifically asked to by a helper. Also, due to the power of this tool it is strongly advised that you do not attempt to act upon any of the information displayed by ComboFix without supervision from someone who has been properly trained. If you do so, it may lead to problems with the normal functionality of your computer.
It should also be noted that when you run ComboFix it will automatically delete files from the following locations:
  • Windows Recycle Bin
  • Temporary Internet Files
  • Temp Folder
If you store files that you wish to keep in one of these location, it is suggested that you move them to a safer location rather than relying on the above temporary storage locations. Please note that this guide is the only authorized guide for the use of ComboFix and cannot be copied without permission from BleepingComputer.com and sUBs. Furthermore, the ComboFix program cannot be hosted at any other site without direct permission from the developer. It is also understood that the use of ComboFix is done at your own risk.

 Using ComboFix
If you need help with malware removal, then please create a topic at one of the forums listed later in the guide and ask for help. Please note that each forum has different policies, so please be sure to read any pinned topics and rules for the particular forum about how you should go about receiving help. If a ComboFix log has been requested by a helper then please create one by following the instructions below.
The first thing you should do is print out this guide, as we will close all the open windows and programs, including your web browser, before starting the ComboFix program.
Next you should download ComboFix from one of the following URLs:
To download ComboFix, simply left-click on one of the links above and you will see a prompt similar to the figure below.

Download ComboFix Screenshot
Download ComboFix Prompt

Click on the Save button, and when it asks you where to save it, make sure you save it directly to your Windows Desktop. An image showing this is below.

Downloading ComboFix to the Desktop
Downloading ComboFix to the Desktop

When you have the Save as screen configured to save ComboFix.exe to the Desktop, click on the Save button. ComboFix will now start downloading to your computer. If you are on a dialup, this may take a few minutes. When ComboFix has finished downloading you will now see an icon on your desktop similar to the one below.

ComboFix Icon
ComboFix Icon

We are almost ready to start ComboFix, but before we do so, we need to take some preventative measures so that there are no conflicts with other programs when running ComboFix. At this point you should do the following:
  • Close all open Windows including this one.
  • Close or disable all running Antivirus, Antispyware, and Firewall programs as they may interfere with the proper running of ComboFix. Instructions on disabling these type of programs can be found in this topic.
Once these two steps have been completed, double-click on the ComboFix icon found on your desktop. Please note, that once you start ComboFix you should not click anywhere on the ComboFix window as it can cause the program to stall. In fact, when ComboFix is running, do not touch your computer at all. The scan could take a while, so please be patient.
Once you double-click on the icon, you may see a screen similar to the one below.

Windows Open File Security Warning
Windows Open File Security Warning

Windows is issuing this prompt because ComboFix does not have a digital signature. This is perfectly normal and safe and you can click on the Run button to continue. If you are using Windows Vista, and receive UAC prompt asking if you would like to continue running the program, you should press the Continue button.
You will now see the first ComboFix screen as shown below.

ComboFix is Preparing to Run
ComboFix is Preparing to Run

ComboFix is now preparing to run and when it has finished you will see a screen showing the authorized locations to download Combofix. On this screen please press the OK button and you will be shown the Disclaimer screen shown below.

ComboFix Disclaimer
ComboFix Disclaimer

If you do not agree to the disclaimer, then click on the No button to exit the program. Otherwise, to continue you should press the Yes button to continue. If you decided to continue, then ComboFix will create a System Restore point so that if any problems occur while using the program you can restore back to your previous configuration. When ComboFix has finished creating the restore point, it will then backup your Windows Registry as shown in the image below.

ComboFix is backing up the Windows Registry
ComboFix is backing up the Windows Registry

Once the Windows Registry has finished being backed up, ComboFix will attempt to detect if you have the Windows Recovery Console installed. If you already have it installed, you can skip to this section and continue reading. Otherwise you will see the following message as shown below:

ComboFix Recovery Console
ComboFix Recovery Console

At the above message box, please click on the Yes button in order for ComboFix to continue. Please follow the steps and instructions given by ComboFix in order to finish the installation of the Recovery Console. Once it has finished installing, you will be presented with the screen shown below.

ComboFix Recovery Console Finished
ComboFix Recovery Console Finished

You should now press the Yes button to continue. If at any time during the Recovery Console installation you receive a message stating that it failed to install, please allow ComboFix to continue with the scan of your computer. When it is done, and a log has been created, you can then perform the manual install of the Recovery Console using the steps found in the Manually installing the Windows Recovery Console section.
ComboFix will now disconnect your computer from the Internet, so do not be surprised or concerned if you receive any warnings stating that you are no longer on the Internet. When ComboFix has finished it will automatically restore your Internet connection.
ComboFix will now start scanning your computer for known infections. This procedure can take some time, so please be patient.

ComboFix is scanning the computer for infections
ComboFix is scanning the computer for infections

While the program is scanning your computer, it will change your clock format, so do not be concerned when you see this happen. When ComboFix is finished it will restore your clock settings to their previous settings. You will also see the text in the ComboFix window being updated as it goes through the various stages of its scan. An example of this can be seen below.

Stages of the ComboFix AutoScan
Stages of the ComboFix AutoScan

At the time of this writing there are a total of 50 stages as shown in the image below, so please be patient. The amount of stages will go up as time goes on, so if the amount of stages is different when you run it, please do not be concerned.

34th Stage of the ComboFix AutoScan
34th Stage of the ComboFix AutoScan

When ComboFix has finished running, you will see a screen stating that it is preparing the log report as shown below.

ComboFix is preparing the log report
ComboFix is preparing the log report

This can take a while, so please be patient. If you see your Windows desktop disappear, do not worry. This is normal and ComboFix will restore your desktop before it is finished. Eventually you will see a new screen that states the program is almost finished and telling you the programs log file, or report, will be located at C:\ComboFix.txt. This can be seen in the image below.

ComboFix is almost done!
ComboFix is almost done!

When ComboFix has finished, it will automatically close the program and change your clock back to its original format. It will then display the log file automatically for you as shown below.

ComboFix Log File
ComboFix Log File

You should now post this log as a reply to the topic where you were asked to run combofix. Your helper will now analyze this log and let you know what they would like you to do next. If you having problems connecting to the Internet after running Combofix, then please read the Manually restoring the Internet connection section.
It is possible that ComboFix, even on its first run, may have fixed the problems you are having. We strongly suggest that you still post your log into the topic that you are receiving help as you most likely will have infections left over that your helper will need to analyze further.

REFERENCES
http://www.bleepingcomputer.com/combofix/how-to-use-combofix