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Majestic-12 : DSearch : Fake MJ12bot v1.0.8

In late 2007/early 2008, a number of fake bot reports were received by Majestic for the bot version 1.0.8. Whilst these have not been reported for some time, Majestic is interested to hear of any reports of bots hitting a site where the User Agent containing the keywords "MJ12bot" and "1.0.8". Email us at with any reports of suspect MJ12bot activity.

Fake MJ12bot v1.0.8 (virus based botnet)

31 Aug 2008: this information is now kept for historical purposes only - the fake bot has not appeared for a long time now, thankfully!

Below you can see extensive information about fake MJ12bot - we have not received any reports of such fake bot since Feb 2008, however we decided to keep the information below as it was posted at the time for historical purposes. Short summary - virus botnet unrelated to us used user-agent of our old bot.

20 Oct 2007 - in the last few days it has been brought to our attention that a number of fake MJ12bots appeared on the Net. These bots are not ours but they use fake MJ12bot user-agent - this is something we can't do anything about just like with email spammers who fake email addresses so we all get spammed supposedly from our own emails or someone elses. :(

6 Dec 2007 - there appears to be a surge in activity of the fake bots in the last few weeks, we have added many more IPs for you to block. They seem to be part of a botnet, unfortunately we do not know who and why does this stuff, the best we can do is take reports of these fakes and publish their IPs for everyone to block. This is a very difficult situation for us as our reputation being affected by those scumbags, we hope you understand this situation and direct your anger to those bad guys rather than us - we really don't have anything to do with this behavior :'-(

28 Dec 2007 - we continue to get reports from people about fake bot. It has now became certain that this bot is actually a virus of some kind that installs itself on end user computers and turns them into botnet - currently anti-virus vendors do not appear to catch this malware, however we are working very hard trying to collect data that will help develop a cure against this virus. Yet again we stress that we have nothing whatsoever to do with those people - our software is not used, they just use fake user-agent that we started using more than 3 years ago.

30 Dec 2007 - if your PC has been infected by this botnet please report this at Kaspersky forum (anti-virus vendor) thread. This fake bot is now known to be 100% a virus of some kind that seems to have infected a lot of people, yet again we want to stress that they don't use our software (it can't be used this way) and they just fake user-agent to look like us :( If you wish to discuss this fake bot on our forum you can do so here (you can post anonymously there, no need to register).

31 Dec 2007 - Breaking news! Kaspersky Labs have successfully identified this virus and it's detection and removal will be included in the next release! Here is relevant thread from their forum. They called this fake MJ12bot virus thingy as: Trojan.Win32.Agent.dqy and Trojan.Win32.Zapchast.dv. I am going to ask user that supplied infected files to Kaspersky to forward them to me so that I could pass them along to other anti-virus companies, hopefully they will be as quick as Kaspersky and produce a cure for everyone, though we can't be 100% sure that this botnet will disappear, but at least right now we know for fact that it was a malicious virus that, yet again, had nothing to do with us! Happy New Year to everyone and lets hope criminals who made this virus will get what they deserve!

6 Jan 2008 - number of reports about this virus appear to be going down, we don't know right now if this is because low lifes who run it took a holiday or anti-viruses are catching this infection more effectively than before - I certainly hope the latter is the case. In any even I hope now that it is proven that this fake bot was a virus that had nothing to do with us, people can see that we were the innocent party in this, victims just like those webmasters hit by this virus. We did all we could in trying to stop this pest, including paying a small cash bounty to an infected person who helped in trying to locate this pest. We did this because we were as pissed off as you, let's hope this problem will go away forever and never return.


Best solution is to ban fake bot using user-agent that it claims to be with keywords: "MJ12bot" and "1.0.8" - any MJ12bot claiming to be this version is fake because we don't use this version for a long time. Below you can see two approaches to this, both of which require Apache, anyone running Microsoft IIS might have similar tools that can pattern match user-agent and ignore requests from those matched, if you do then please let us know.

Solution 1: blog entry how to block in Apache fake MJ12bots claiming to be v1.0.8, read more below about them or go to the good people of to get this block that does not depend on IP address of this fake bot. Our good bot obeys your robots.txt file, so if you wish to disallow it then it is best to use robots.txt.

Solution 2 (updated: 6/01/08): Suggested by Ken from add to .htaccess the following: RewriteCond %{HTTP_USER_AGENT} MJ12bot/v1\.0\.8 [NC]
RewriteRule ^.* - [F]

Alternative suggestion from Paul to have this htaccess rule as follows:

RewriteCond %{HTTP_USER_AGENT} ^MJ12bot/v1\.0\.8.*$
RewriteRule .* - [F]

Another suggestion from Olliver W.

On another note, in your tips and tricks section for dealing
appropriately with this fake bot you were mentioning some sample entries
to be added to httpd.conf or .htaccess (depending on the level of access
one has on the server), but I noticed Mod SetEnvIf is missing. So
here is a step by step guide for Apache users:

1. First create a section for mod setenvif in case it does not exist. It
is not dependent from any Directory/Location directives and can be placed
in both httpd.conf and .htaccess

# deny fake bot
SetEnvIfNoCase User-Agent "^MJ12bot/v?1\.[01]\.[0-9]{1,2}" block

This entry will create an environmental variable called "block" in case
of a match. The match itself is a bit more sophisticated to catch any
modifications that are likely to happen once the old Agent no longer
achieves its goal. It denies access for any 1.0.x or 1.1.x version and
works even if the "v" was omitted.

2. Create an entry what to do with the variable in case it is set

Deny from env=block

In .htaccess this line merely needs to be placed after the SetEnvIfRule,
but those who want to include it in httpd.conf, have to take care of
placing it within their VirtualHost section. An example as illustration:

  # Directory permissions
    Options Indexes FollowSymlinks MultiViews
    AllowOverride All
    Order deny,allow
    # apply SetEnvIfRule here
    Deny from env=block

This should give 403 Forbidden errors to fake bot requests.

Solution 3: Suggested by Michael B. - if you have Cold-Fusion then add the following to application.cfm:

<cfif cgi.HTTP_USER_AGENT contains "MJ12bot/v1.0.8">
<cflocation url="">

This should result in requests by fake bot redirected to the FBI, maybe this will make them interested, I sure hope so and will be pretty happy if those fake bot guys get waterboarded in Guantanamo, harsh but just treatment that they surely deserve! Note: we don't know for certain if their fake bot supports redirects at all, it probably does though.

You might be tempted to ban anything that has got MJ12bot in user-agent. This is not wise for 2 reasons: first you will prevent our good bot from obeying your robots.txt because it won't be able to get it, and secondly you will help bad guys achieve what they probably want - ruin our reputation as good guys and make people ban our good bot. We don't know if the bad guys who run this fake bot want that or they just picked our user-agent randomly, but if you hate those guys as much as we do, then don't allow them to achieve their goals.

Solution 4: ban known fake MJ12bot IPs - you can ban those right now as they are known to be used by fakers: [removed IPs since they no longer relevant]

The list of IPs is pretty big. Initially it was small, but then it grown up pretty quickly - it seems that those guys run their bot that pretends to be us on a big botnet, which is why IPs are so varied. Banning by IP is therefore not the best approach - it is better to catch user-agent MJ12bot/v1.0.8 as described above. We will keep this list however to show our good faith towards those who got hit by this bot - we will add your IPs to this public list to demonstrate that we have nothing to do with those people, whoever they are.

If you are in doubt whether the bot that crawled your site is genuine then please use contact information at the bottom of this page to tell us about it and we will give answer whether this is a genuine or fake MJ12bot bot. Once again to reiterate - we don't know who fakes our user-agent and for what purposes, but you can be sure that this is not us.

The way to distinquish those fake bots is this:

  1. Too old version: v1.0.8 - current bot version is v1.4.1 (v1.4.2 is also valid until Feb 2012) - if you see v1.0.8 of the bot then it is fake, tell us its IP though please as we want to add it to the list of fake bots IPs above!
  2. Does not retrieve immediately prior to crawling urls or no more than 24 hours ago robots.txt, and does not obey it
  3. "Accept" header: */* (genuine is normally "text/html,text/plain,text/xml,text/*,application/xml,application/xhtml+xml") (thanks to Borg for this information)

If you have any scripts that check for user-agents then you can safely ban any MJ12bot that claims to be v1.0.8 - this old version that is not in use now is definately a fake. But please consider not banning whole of MJ12bot in robots.txt - it won't save you from fake bots that ignore robots.txt.

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