Alert level

Win32/Sefnit

(?)

Encyclopedia entry
Updated: May 29, 2012  |  Published: Dec 12, 2011

Aliases
Not available

Alert Level (?)
Severe

Antimalware protection details
Microsoft recommends that you download the latest definitions to get protected.


 

Summary

Win32/Sefnit is a trojan that may monitor Internet Explorer or Mozilla Firefox to hijack the search results for various search engines such as Bing, Yahoo! and Google.



 

Symptoms

There are no common symptoms associated with this threat. Alert notifications from installed antivirus software may be the only symptoms.



 

Technical Information (Analysis)

Win32/Sefnit is a trojan that may monitor Internet Explorer or Mozilla Firefox to hijack the search results for various search engines such as Bing, Yahoo! and Google.

Installation

Win32/Sefnit may arrive in the system as an executable and drop a DLL component using varied file and folder names, for example:

  • %AppData%\handlereventinterval\mfcuserppm.dll
  • %Temp%\Asynccrtmon.dll

It launches its dropped copies by running using "rundll32.exe":

rundll32.exe "%AppData%\HandlerEventInterval\mfcUserppm.dll",wmicfgSnap rasCommsspl
rundll32.exe "%Temp%\Asynccrtmon.dll", wmicfgSnap AppleapiClock

It modifies the registry so that its dropped copy automatically executes every time Windows starts, as in the following example:

In subkey: HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
Sets value: "<malware file name>"
With data: "rundll32.exe "<malware path and location>",<export name> <parameter>"

For example:

In subkey: HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
Sets value: "mfcUserppm"
With data: "rundll32.exe "%AppData%\handlereventinterval\mfcuserppm.dll",wmicfgsnap rascommsspl"

Payload

Hijacks search engine results
Win32/Sefnit may monitor Internet Explorer and Mozilla Firefox to hijack search the results for various search engines such as Bing, Yahoo! and Google.

Communicates with remote servers
Variants of Win32/Sefnit attempt to communicate with remote servers to send and receive data. In the wild, we have observed this malware to communicate with the following IP addresses for this purpose:

  • 213.239.212.16
  • 85.10.195.238
  • 78.47.143.235
  • 208.91.197.65

Analysis by Scott Molenkamp



 

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 webpages.
  • 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. Instructions on how to download the latest versions of some common software is available from the following:

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/windows/antivirus-partners/.

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 webpages

Exercise caution with links to webpages 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.



 

Recovery

To detect and remove this threat and other malicious software that may be installed on your computer, run a full-system scan with an appropriate, up-to-date, security solution. The following Microsoft products detect and remove this threat:

For more information on antivirus software, see http://www.microsoft.com/windows/antivirus-partners/.

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