Additional Information on Conficker – MSRT removing Conficker

Over the last few days I blogged several times about Conficker and some of the posts caught quite some press attention. Especially when I talked about the Russian Roulette.

Today I have very, very good news: The Malicious Software Removal Tool (MSRT) which we will release today includes signatures to remove Conficker as far as we know this beast today. Let me be clear upfront: MSRT is cleaning up after the fact and is no replacement for an updated Anti-Malware solution!

The information in this post is the information as far as I have it as of today. The links below give you the ultimate guidance:

How do you realize that you are infected?

Trust me, you will know! If you have Account Lockout Policies set, your accounts will be locked as Conficker.B does a brute-force against the accounts. In parallel, you will see a significant increase of authentication requests on your DCs due to that fact. Most probably you find a significant increase of network traffic as well and last but not least your clients may behave strange.

If you have it what can you do against it?

Patch first! So, before you do anything else, deploy MS08-067. I already said once, that you played Russian Roulette if you did not. From there on, you have to clean the mess. But first, make sure you use strong passwords (Conficker is trying to break them). Here you find some good information and guidance on passwords:


What you should know about strong passwords:

Password Best Practices:

Accounts Passwords and Lockout Policies:

Account Lockout and Management Tools:



If you want to change all your local Admin passwords and manage them, Steve Riley provided a tool called Passgen

Then clean up…

You have different options to do the clean up:

  • Forefront and OneCare have been one of the first solutions to clean Conficker since quite a while. Our free online scanner does it too (since quite a while). You can find it on
  • The updated Malicious Software Removal Tool removes it as well. However, remember that Conficker breaks Automatic Updates too. So, if you are infected you have to manually download and deploy it. Here are the relevant KBs:
    • KB890830 The Microsoft Windows Malicious Software Removal Tool helps remove specific, prevalent malicious software from computers that are running Windows Vista, Windows Server 2003, Windows XP, or Windows 2000
    • KB891716 Deployment of the Microsoft Windows Malicious Software Removal Tool in an enterprise environment
  • There are definitely other AV products that remove it as well. Make sure and check back with your vendor whether it removes or just detects it.

One final thing: If you are infected, do NOT log onto the system with a Domain account, if at all possible. Especially NOT a Domain Admin account. Log on as a local user account. The malware appears to impersonate the logged on user and access network resources under those users credentials so it can spread.

So, that’s it for the moment.

I hope it helps