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Win32/Stration


Win32/Stration is a family of mass-mailing email worms that send themselves to addresses obtained from a wide range of file types found on the infected system. The e-mail message composed by the worm may masquerade as a failure message or as a scanning tool. Win32/Stration also acts as a Trojan downloader, attempting to download a file from a remote website. The downloaded file may be another variant of the Win32/Stration family.


What to do now

Manual removal is not recommended for this threat. Use the Microsoft Malicious Software Removal Tool, Microsoft Security Essentials, Microsoft Safety Scanner, or another up-to-date scanning and removal tool to detect and remove this threat and other unwanted software from your computer. For more information on Microsoft security products, see http://www.microsoft.com/protect/products/computer/default.mspx.

Threat behavior

Win32/Stration is a family of mass-mailing email worms that may terminate processes related to security software, block access to security-related domains, and attempt to download a file from a remote website. Typically, the downloaded file is a new variant of the Win32/Stration worm. Win32/Stration sends itself to addresses obtained from a wide range of file types found on the infected system. The e-mail message composed by Win32/Stration worms may masquerade as one of the following failure messages:
 
Mail transaction failed. Partial message is available.
 
The message contains Unicode characters and has been sent as a binary attachment.
 
The message cannot be represented in 7-bit ASCII encoding and has been sent as a binary attachment
 
The Win32/Stration e-mail message may also masquerade as a scanning tool, as follows:
 
Mail server report.
Our firewall determined the e-mails containing worm copies are being sent from your computer.
Nowadays it happens from many computers, because this is a new virus type (Network Worms).
Using the new bug in the Windows, these viruses infect the computer unnoticeably. After the penetrating into the computer the virus harvests all the e-mail addresses and sends the copies of itself to these e-mail addresses
Please install updates for worm elimination and your computer restoring.
Best regards,
Customers support service
 
 
The Win32/Stration worm attaches a copy of itself as an attachment to the email. Attachment names may vary and may include one of the following:
 
body
data
doc
docs
document
file
message
readme
test
text
Update-KB%random_numbers%-x86 (where %random-number% indicates a series of numbers)
 
Win32/Stration may use a double extension ruse, in which the filenames may be appended with one of the following:
 
.log
.msg
.txt
 
The Win32/Stration attachment generally has one of the following actual extensions:
 
.exe
.scr
.zip
Upon infection, Win32/Stration drops files, usually into the Windows folder (typically C:\Windows\) or the Windows system folder (typically C:\Windows\System32). File names may vary; common examples include:
 
cserv32.exe
cservv32.exe
dpv1usrd.exe
e1.dll
msserv.exe
mswiizz32.exe
nwwksetr.dll
rsmb.exe
rsmpwtsa.exe
serrv.exe
serv.exe
sisbaclu.dll
sserrvv.exe
svchost.exe
t2serv.dll
t2serv.exe
tsrv.exe
 
In order to load when Windows is started, Win32/Stration worms modify the System Registry by adding a value with a path pointing to one of the dropped files to the following registry key:
 
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
 
Win32/Stration may load the dropped DLL files by modifying the following registry key:
 
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\Windows\AppInit_DLLs
 
All the DLLs specified in this value are loaded by each Windows-based application running in the current log on session.
 
Win32/Stration may also register the dropped DLL files to load as Winlogon notification packages by modifying the following registry key:
 
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\Notify\
adding the value: 'acac'
 
The Win32/Stration worms may attempt to delete processes associated with certain antivirus and security software installed on the system. Win32/Stration may also modify the Windows Hosts file in an attempt to block access to certain domains, thereby preventing access to security updates and information which could be used to detect or remove the worm.

Prevention

Take the following steps to help prevent infection on your computer:
  • Enable a firewall on your computer.
  • Get the latest computer updates for all your installed software.
  • Use up-to-date antivirus software.
  • Limit user privileges on the computer.
  • Use caution when opening attachments and accepting file transfers.
  • Use caution when clicking on links to web pages.
  • Avoid downloading pirated software.
  • Protect yourself against social engineering attacks.
  • Use strong passwords.
Enable a firewall on your computer
Use a third-party firewall product or turn on the Microsoft Windows Internet Connection Firewall.
Get the latest computer updates
Updates help protect your computer from viruses, worms, and other threats as they are discovered. It is important to install updates for all the software that is installed in your computer. These are usually available from vendor websites.
 
You can use the Automatic Updates feature in Windows to automatically download future Microsoft security updates while your computer is on and connected to the Internet.
Use up-to-date antivirus software
Most antivirus software can detect and prevent infection by known malicious software. To help protect you from infection, you should always run antivirus software, such as Microsoft Security Essentials, that is updated with the latest signature files. For more information, see http://www.microsoft.com/security/antivirus/av.aspx.
Limit user privileges on the computer
Starting with Windows Vista and Windows 7, Microsoft introduced User Account Control (UAC), which, when enabled, allowed users to run with least user privileges. This scenario limits the possibility of attacks by malware and other threats that require administrative privileges to run.
 
You can configure UAC in your computer to meet your preferences:
Use caution when opening attachments and accepting file transfers
Exercise caution with email and attachments received from unknown sources, or received unexpectedly from known sources.  Use extreme caution when accepting file transfers from known or unknown sources.
Use caution when clicking on links to web pages
Exercise caution with links to web pages that you receive from unknown sources, especially if the links are to a webpage that you are not familiar with, unsure of the destination of, or suspicious of. Malicious software may be installed in your computer simply by visiting a webpage with harmful content.
Avoid downloading pirated software
Threats may also be bundled with software and files that are available for download on various torrent sites. Downloading "cracked" or "pirated" software from these sites carries not only the risk of being infected with malware, but is also illegal. For more information, see 'The risks of obtaining and using pirated software'.
Protect yourself from social engineering attacks
While attackers may attempt to exploit vulnerabilities in hardware or software to compromise a computer, they also attempt to exploit vulnerabilities in human behavior to do the same. When an attacker attempts to take advantage of human behavior to persuade the affected user to perform an action of the attacker's choice, it is known as 'social engineering'. Essentially, social engineering is an attack against the human interface of the targeted computer. For more information, see 'What is social engineering?'.
Use strong passwords
Attackers may try to gain access to your Windows account by guessing your password. It is therefore important that you use a strong password – one that cannot be easily guessed by an attacker. A strong password is one that has at least eight characters, and combines letters, numbers, and symbols. For more information, see http://www.microsoft.com/protect/yourself/password/create.mspx.

Alert level: High
This entry was first published on: Nov 27, 2006
This entry was updated on: Apr 17, 2011

This threat is also detected as:
  • Win32/Stration!generic (CA)
  • W32/Strati-Gen (Sophos)
  • W32.Stration.DL@mm (Symantec)
  • WORM_STRAT.DR (Trend Micro)