W32.Netsky.D@mm

W32.Netsky.D@mm is a mass-mailing worm that uses its own SMTP engine to send itself to all email addresses it gathers from files with the following extensions on drives C through Z:
.dhtm
.cgi
.shtm
.msg
.oft
.sht
.dbx
.tbb
.adb
.doc
.wab
.asp
.uin
.rtf
.vbs
.html
.htm
.pl
.php
.txt
.eml

The email message typically has the following properties:
From address will be spoofed.

Subject can be one of the following:
Re: Your website
Re: Your product
Re: Your letter
Re: Your archive
Re: Your text
Re: Your bill
Re: Your details
Re: My details
Re: Word file
Re: Excel file
Re: Details
Re: Approved
Re: Your software
Re: Your music
Re: Here
Re: Re: Re: Your document
Re: Hello
Re: Hi
Re: Re: Message
Re: Your picture
Re: Here is the document
Re: Your document
Re: Thanks!
Re: Re: Thanks!
Re: Re: Document
Re: Document

Message body can be one of the following:
Your file is attached.
Please read the attached file.
Please have a look at the attached file.
See the attached file for details.
Here is the file.
Your document is attached.

Attachment name will be one of the following:
your_website.pif
your_product.pif
your_letter.pif
your_archive.pif
your_text.pif
your_bill.pif
your_details.pif
document_word.pif
document_excel.pif
my_details.pif
all_document.pif
application.pif
mp3music.pif
yours.pif
document_4351.pif
your_file.pif
message_details.pif
your_picture.pif
document_full.pif
message_part2.pif
document.pif
your_document.pif

It avoids sending email to addresses containing the following strings:
skynet
messagelabs
abuse
fbi
orton
f-pro
aspersky
cafee
orman
itdefender
f-secur
avp
spam
ymantec
antivi
icrosoft

When it is executed, it creates the following copy of itself:
%Windir%\Winlogon.exe

The mutex "[SkyNet.cz]SystemsMutex" is created so that only a single instance of the worm is present in memory at any time.

It then creates the following registry entry so that it executes every time Windows starts:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\"ICQ Net" = "%Windir%\winlogon.exe -stealth"

The worm deletes the values:
Taskmon
Explorer
Windows Services Host
KasperskyAV

from the following registry keys:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Run

It also deletes the values:
System.
msgsvr32
DELETE ME
service
Sentry

from the following registry key:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run

Deletes the values:
d3dupdate.exe
au.exe
OLE

from the registry key:
HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Run

Deletes the value:
System.

from the following registry key:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\RunServices

Deletes the following registry keys:
HKEY_CLASSES_ROOT\CLSID\{E6FB5E20-DE35-11CF-9C87-00AA005127ED}\InProcServer32
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\PINF
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\WksPatch

These values are associated with other worms, most predominantly W32.Mydooom.A@mm (MCID 2468), W32.Mydoom.B@mm (MCID 2475), and W32.Mimail.T@mm (MCID 2499).

If the system time is 0600, 0700, or 0800 on a Tuesday in March of 2004, the worm will cause the PC speaker to beep for a random period of time at a random frequency.

The worm also appears to query the following DNS servers for the MX records of addresses it sends itself to:
212.44.160.8
195.185.185.195
151.189.13.35
213.191.74.19
193.189.244.205
145.253.2.171
193.141.40.42
194.25.2.134
194.25.2.133
194.25.2.132
194.25.2.131
193.193.158.10
212.7.128.165
212.7.128.162
193.193.144.12
217.5.97.137
195.20.224.234
194.25.2.130
194.25.2.129
212.185.252.136
212.185.253.70
212.185.252.73
62.155.255.16

Recommendations

Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":

• Use a firewall to block all incoming connections from the Internet to services that should not be publicly available. By default, you should deny all incoming connections and only allow services you explicitly want to offer to the outside world.
• Enforce a password policy. Complex passwords make it difficult to crack password files on compromised computers. This helps to prevent or limit damage when a computer is compromised.
• Ensure that programs and users of the computer use the lowest level of privileges necessary to complete a task. When prompted for a root or UAC password, ensure that the program asking for administration-level access is a legitimate application.
• Disable AutoPlay to prevent the automatic launching of executable files on network and removable drives, and disconnect the drives when not required. If write access is not required, enable read-only mode if the option is available.
• Turn off file sharing if not needed. If file sharing is required, use ACLs and password protection to limit access. Disable anonymous access to shared folders. Grant access only to user accounts with strong passwords to folders that must be shared.
• Turn off and remove unnecessary services. By default, many operating systems install auxiliary services that are not critical. These services are avenues of attack. If they are removed, threats have less avenues of attack.
• If a threat exploits one or more network services, disable, or block access to, those services until a patch is applied.
• Always keep your patch levels up-to-date, especially on computers that host public services and are accessible through the firewall, such as HTTP, FTP, mail, and DNS services.
• Configure your email server to block or remove email that contains file attachments that are commonly used to spread threats, such as .vbs, .bat, .exe, .pif and .scr files.
• Isolate compromised computers quickly to prevent threats from spreading further. Perform a forensic analysis and restore the computers using trusted media.
• Train employees not to open attachments unless they are expecting them. Also, do not execute software that is downloaded from the Internet unless it has been scanned for viruses. Simply visiting a compromised Web site can cause infection if certain browser vulnerabilities are not patched.
• If Bluetooth is not required for mobile devices, it should be turned off. If you require its use, ensure that the device's visibility is set to "Hidden" so that it cannot be scanned by other Bluetooth devices. If device pairing must be used, ensure that all devices are set to "Unauthorized", requiring authorization for each connection request. Do not accept applications that are unsigned or sent from unknown sources.
• For further information on the terms used in this document, please refer to the Security Response glossary.

Summary