A new variant of Mimail worm - Mimail.M was found on 3rd of
The worm sends messages with seemingly personal content that
promises pictures in a ZIP file which contains the worm instead.
Mimail.M also performs Distributed Denial-of-Service attacks
against certain websites.
Manual disinfection of an Mimail.M infected computer consists of
the following steps:
1, Remove the registry value
2, Restart the computer
3, Delete '%WinDir%\netmon.exe' (where %WinDir% is the
Windows Directory, typically c:\windows\ or c:\winnt)
The worm spreads in UPX packed form. The packed file is 10784
bytes in size. The unpacked worm body size is 23072 bytes and it
was written in C language.
Mimail.M arrives in emails with the following characteristics:
From: "Wendy" <some@email>
Subject: Re <random string>
I was shocked, when I found out that it wasn't you but your
twin brother!!! That's amazing, you're as like as two
peas. No one in bed is better than you Greg. I remember, I
remember everything very well, that promised you to tell
how it was, I'll give you a call today after 9.
<explicit content removed>
I'm so thankful to you, for acquainted me to your brother.
I think we can do it on the next Saturday all three
together? What do you think? O yes, as you wanted I've made
a few pictures check them out in archive, I hope they will
excite you, and you will dream of our new meeting...
It has been reported that Mimail.M was seeded using the message
above with an attachment called 'wendy.zip' which is 9903 bytes
in size. The zip archive in the seed emails is password protected
and the password is included at the end of the email message as
well as a link to the archiver's download web page.
The worm collects email addresses from files on the infected computer.
It recursively searches through the user's document folders and
looks into all the files whose extension is not on the following list
Using its own SMTP engine it sends emails with the malicious
attachment. To find the SMTP server of the target email address
the worm does an MX lookup using a predefined public DNS server.
When started, Mimail.L first copies itself to the Windows Directory
as 'netmon.exe'. This copy is added to the registry as
to make sure the worm is started when Windows starts.
The worm creates several temporary files in the Windows directory:
%WinDir%\msi2.tmp - worm packed into a ZIP file
%WinDir%\nji2.tmp - copy of the worm
%WinDir%\xjwu2.tmp - list of collected email addresses
As payload Mimail.M contains routines to perform Distributed
Denial-of-Service attacks against the following sites:
Detection in F-Secure Anti-Virus was published in update:
Gergely Erdelyi, December 3rd, 2003;
Katrin Tocheva, December 3rd, 2003;