The W32.Klez.H@mm worm is a modified variant of the W32.Klez.E@mm. This variant can spread by email and network shares. It is also capable of infecting files.
This worm infects executables, by creating a hidden copy of the original host
file, and then by overwriting the original file with itself. The hidden copy
is encrypted, but contains no viral data. The name of the hidden file is the
same as the original file, but with a random extension.
Large scale e-mailing: This worm searches the Windows address book, the ICQ database, and local files for email addresses. The worm sends an email message to these addresses with itself as an attachment.
Releases confidential info: Worm randomly chooses a file from the machine to send with the worm to recipients. So, the files with the extensions: ".mp8", ".txt", ".htm", ".html", ".wab", ".asp", ".doc", ".rtf", ".xls", ".jpg", ".cpp", ".pas", ".mpg", ".mpeg", ".bak", ".mp3", or ".pdf" would be attached to the email messages with the viral attachment.
of email: Random
Name of attachment: Random
Copying local and network drives
worm copies itself to local, mapped, and network drives as:
A random file name with a double extension. For example, Filename.txt.exe.
A .rar archive with a double extension. For example, Filename.txt.rar.
This worm searches the Windows address book, the ICQ database, and local files for email addresses. It sends an email message to these addresses with itself as an attachment. The worm contains its own SMTP engine and attempts to guess at available SMTP servers.
For example, if the worm encounters the address firstname.lastname@example.org, it attempts to send email via the server smtp.abc123.com.
The subject line, message bodies, and attachment file names are random. The From address is randomly chosen from email addresses that the worm finds on the infected computer.
will the search files with the following extensions for the email addresses:
Technical Details: When this worm is executed, it does the following:
1. Copies itself to \%System%\Wink<random characters>.exe.
NOTE: %System% is a variable. The worm locates the Windows System folder (by default, this is C:\Windows\System or C:\Winnt\System32) and copies itself to that location.
2. Adds the value:
Wink<random characters> %System%\Wink<random characters>.exe
to the registry key:
or, it creates the registry key:
HKEY_LOCAL_MACHINE\System\ CurrentControlSet\Services\Wink[random characters]
and inserts a value in this subkey, so that the worm executes when you start Windows.
to disable on-access virus scanners and some previously distributed worms
(such as W32.Nimda and CodeRed), by stopping any active processes. The worm
removes the startup registry keys, used by antivirus products, and deletes
the checksum database files, including:
addition to the worm attachment, the worm may also attach a random file from
the computer. The file will have one of the following extensions:
As a result, the email message would have two attachments, the first being the worm and the second being the randomly selected file.
"Random" strings comprise the email message that this worms sends. The subject can be one of the following:
Undeliverable mail--"[Random word]"
Returned mail--"[Random word]"
a [Random word] [Random word] game
a [Random word] [Random word] tool
a [Random word] [Random word] website
a [Random word] [Random word] patch
[Random word] removal tools
how are you
let's be friends
so cool a flash,enjoy it
please try again
welcome to my hometown
the Garden of Eden
introduction on ADSL
japanese girl VS playboy
look,my beautiful girl friend
eager to see you
spice girls' vocal concert
japanese lass' sexy pictures
word is one of the following:
The body of the email message is random.
This worm often uses a technique called "spoofing." When the worm performs its email routine, it can use a randomly chosen address it finds on an infected computer as the "From:" address. Numerous cases have been reported in which users of uninfected computers received complaints that they sent an infected message to someone else.
For example, Linda Anderson is using a computer infected with W32.Klez.H@mm. Linda is not using an antivirus program or does not have the current virus definitions. When W32.Klez.H@mm performs its emailing routine, it finds the email address of Harold Logan. The worm inserts Harold's email address into the "From:" portion of an infected message, which the worm then sends to Janet Bishop. Then, Janet contacts Harold and complains that he sent her an infected message, but when Harold scans his computer, Norton AntiVirus does not find anything because his computer is not infected.
If you are using a current version of Norton AntiVirus, have the most recent virus definitions, and a full system scan with Norton AntiVirus, which is set to scan all the files, does not find anything, you can be confident that your computer is not infected with this worm.
There have been several reports that, in some cases, if you receive a message that the virus has sent using its own SMTP engine, the message appears to be a "postmaster bounce message" from your own domain. For example, if your email address is email@example.com, you could receive a message that appears to be from firstname.lastname@example.org, indicating that you attempted to send an email and the attempt failed. If this is the false message sent by the virus, the attachment includes the virus itself. Of course, such attachments should not be opened.
The message may be disguised as an immunity tool. One version of this false message is:
Klez.E is the most common world-wide spreading worm. It's very dangerous by corrupting your files. Because of its very smart stealth and anti-anti-virus technic,most common AV software can't detect or clean it.We developed this free immunity tool to defeat the malicious virus. You only need to run this tool once,and then Klez will never come into your PC.
NOTE: Because this tool acts as a fake Klez to fool the real worm,some AV monitor maybe cry when you run it. If so,Ignore the warning,and select 'continue'. If you have any question,please mail to me.