Alert level

Trojan:Win32/Alureon.CT


Encyclopedia entry
Updated: Oct 26, 2009  |  Published: Oct 23, 2009

Aliases
  • Win32/Tidserv.H (CA)
  • Packed.Win32.Tdss.w (Kaspersky)
  • W32/DNSChanger.FUBV (Norman)
  • Trojan.Tdss.HWD (VirusBuster)
  • DNSChanger!bc (McAfee)
  • Backdoor.Tidserv (Symantec)

Alert Level (?)
Severe

Antimalware protection details
Microsoft recommends that you download the latest definitions to get protected.
Detection last updated:
Definition: 1.69.1105.0
Released: Nov 18, 2009 		Detection initially created:
Definition: 1.67.549.0
Released: Oct 08, 2009

Summary

Trojan:Win32/Alureon.CT is a trojan that may send system information to a remote address.
 
For more information refer to the description for the Win32/Alureon family.

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Symptoms

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

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Technical Information (Analysis)

Trojan:Win32/Alureon.CT is a trojan that may send system information to a remote address.
 
The Alureon family is also known to change a system's DNS settings. The Domain Name System (DNS) is used (among other things) to map domain names to IP addresses - that is, to map human-readable domain names to machine-readable IP addresses. When a user attempts to visit a particular URL, a browser will use DNS servers to find the correct IP address of the requested domain. When a user is directed to a malicious server that is not part of the authoritative Domain Name System, an attacker can provide incorrect IP addresses at their choice to map to particular domain names, thus directing the user to possibly bogus or malicious sites without the affected user's knowledge.
 
For more information refer to the description for the Win32/Alureon family.
Installation
Trojan:Win32/Alureon.BE may be downloaded or dropped by other members of the Alureon family. It is usually installed or dropped in the following location:
 
<system folder>\spool\PRTPROCS\W32X86\<random letter or number>.tmp
 
For example:
 
E.tmp
 
It injects its code into the legitimate process 'spoolsv.exe'.
Payload
Drops other malware
Trojan:Win32/Alureon.CT drops the following file:
 
%Temp%\<random letter or number>.tmp (for example, F.tmp) - this file is detected as Trojan:WinNT/Alureon.G
 
It creates the following registry entry to enable its dropped file to run as a service:
 
Adds value: "Image Path"
With data: "%Temp%\<random number or letter>.tmp"
In subkey: HKLM\System\Currentcontrolset\Services\tdlserv
 
It may also drop other files in the system as:
 
tdlcmd.dll - detected also as Trojan:Win32/Alureon.CT
tdlwsp.dll - detected as Trojan:Win32/Alureon.gen!U
config.ini - contains malware information
 
Connects to remote servers
Trojan:Win32/Alureon.CT may connect to the following remote servers and IP address:
 
  • h3456345.cn
  • h9237634.cn
  • 212.117.174.173
 
It may then send information about the infected system to these servers.
 
Analysis by Tim Liu

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Prevention

Take the following steps to help prevent infection on your system:
  • Enable a firewall on your computer.
  • Get the latest computer updates for all your installed software.
  • Use up-to-date antivirus software.
  • 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.
To turn on the Windows Firewall in Windows Vista
  1. Click Start, and click Control Panel.
  2. Click Security.
  3. Click Turn Windows Firewall on or off.
  4. Select On.
  5. Click OK.
To turn on the Internet Connection Firewall in Windows XP
  1. Click Start, and click Control Panel.
  2. Click Network and Internet Connections. If you do not see Network and Internet Connections, click Switch to Category View.
  3. Click Change Windows Firewall Settings.
  4. Select On.
  5. Click OK.
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.
To turn on Automatic Updates in Windows Vista
  1. Click Start, and click Control Panel. 
  2. Click System and Maintainance.
  3. Click Windows Updates.
  4. Select a setting. Microsoft recommends selecting Install updates automatically and choose a time that is convenient for you. If you do not choose Automatic, but you choose to be notified when updates are ready, a notification balloon appears when new downloads are available to install. Click the notification balloon to review and install the updates.
To turn on Automatic Updates in Windows XP
  1. Click Start, and click Control Panel. 
  2. Click System.
  3. Click Automatic Updates.
  4. Select a setting. Microsoft recommends selecting Automatic. If you do not choose Automatic, but you choose to be notified when updates are ready, a notification balloon appears when new downloads are available to install. Click the notification balloon to review and install the updates.
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/protect/computer/viruses/vista.mspx.
Use caution when opening attachments and accepting file transfers
Exercise caution with e-mail 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 Web page that you are not familiar with, unsure of the destination of, or suspicious of. Malicious software may be installed in your system simply by visiting a Web page 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 in order to compromise a system, they also attempt to exploit vulnerabilities in human behavior in order to do the same. When an attacker attempts to take advantage of human behavior in order 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 system. 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 8 characters, and combines letters, numbers, and symbols. For more information, see http://www.microsoft.com/protect/yourself/password/create.mspx.

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Recovery

Manual removal is not recommended for this threat. To detect and remove this threat and other malicious software that may have been installed, run a full-system scan with an up-to-date antivirus product such as Microsoft Security Essentials, or the Windows Live OneCare safety scanner. For more information about using antivirus software, see http://www.microsoft.com/security/antivirus/av.aspx.
 
The Domain Name System (DNS) is used (among other things) to map domain names to IP addresses - that is, to map human-readable domain names to machine-readable IP addresses. When a user attempts to visit a particular URL, a browser will use DNS servers to find the correct IP address of the requested domain. When a user is directed to a malicious server that is not part of the authoritative Domain Name System, an attacker can provide incorrect IP addresses at their choice to map to particular domain names, thus directing the user to possibly bogus or malicious sites without the affected user's knowledge.
 
Win32/Alureon may modify DNS settings on the host computer, thus the following steps may be required after the Win32/Alureon removal is complete:
  • If the computer has a network interface that does not receive a configuration using DHCP, reset the DNS configuration if necessary. For information on configuring TCP/IP to use DNS in Windows XP, see http://support.microsoft.com/kb/305553

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