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Win32/Cycbot


Win32/Cycbot is a backdoor trojan that allows attackers unauthorized access and control of an affected computer. After a computer is infected, the trojan connects to a specific remote server to receive commands from attackers. The commands may include instructing the trojan to update itself, visit web links, or download and execute arbitrary files. The trojan may also allow attackers to perform other backdoor functions, such as launching denial of service (DoS) attacks and retrieving system information from infected computers.


What to do now

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 will detect and remove this threat:
 
 
For more information on antivirus software, see http://www.microsoft.com/windows/antivirus-partners/.

Threat behavior

Win32/Cycbot is a backdoor trojan that allows attackers unauthorized access and control of an affected computer. After a computer is infected, the trojan connects to a specific remote server to receive commands from attackers. The commands may include instructing the trojan to update itself, visit web links, or download and execute arbitrary files. The trojan may also allow attackers to perform other backdoor functions, such as launching denial of service (DoS) attacks and retrieving system information from infected computers.
Installation
When executed, Win32/Cycbot copies itself as the following:
 
%APPDATA%\Microsoft\svchost.exe.

The malware modifies the registry to ensure that its copy executes at each Windows start.

In subkey: HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
Sets value: "svchost"
To data: "%APPDATA%\Microsoft\svchost.exe"
 
or
 
In subkey: HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
Sets value: "svchost"
To data: "%APPDATA%\Microsoft\svchost.exe"
 
The malware creates the following files on an affected computer:
  • %APPDATA%\Microsoft\stor.cfg
  • %APPDATA%\Microsoft\windows\shell.exe
  • %TEMP%\dwm.exe
 
These files store configuration and logging information for the malware.
Payload
Allows backdoor access and control
Win32/Cycbot allows unauthorized access and control of an affected computer. It does so by connecting to one of a number of web servers, which may respond with commands for it to execute. It may also send status information to these servers. Examples of servers used by the malware include the following:
 
protectyourpc-11.com
qudeteyuj.cn
178.63.123.226
dolbyaudiodevice.com
zoneck.com
136136.com
motherboardstest.com
zonejm.com
freeonlinedatingtips.net
blenderartists.org
pcdocpro.com
historykillerpro.com
sharewareconnection.com
xy95.cn
8minutedating.com
securemywebconnection.com
mywwwarchive.com
testpcdriversonline.com
biggamemonitoring.com
bigkeystore.com
internetsecure.com
 
An attacker can perform any number of different actions on an affected computer using Win32/Cycbot. This could include, but is not limited to, the following actions:
 
  • Download and execute arbitrary files
  • Upload files
  • Spread to other computers using various methods of propagation
  • Log keystrokes or steal sensitive data
  • Modify system settings
  • Run or terminate applications
  • Delete files
 
Downloads and installs additional malware
Variants of Win32/Cycbot has been observed to download and execute fake security software, such as Rogue:Win32/FakePAV.
 
Analysis by Hamish O'Dea

Symptoms

System changes
The following system changes may indicate the presence of this malware:
  • The presence of the following files:

    %APPDATA%\Microsoft\stor.cfg
    %APPDATA%\Microsoft\svchost.exe
    %APPDATA%\Microsoft\windows\shell.exe
    %TEMP%\dwm.exe
  • The presence of the following registry modifications:
    In subkey: HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    or subkey: HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    Sets value: "svchost"
    To data: "c:\documents and settings\administrator\application data\microsoft\svchost.exe"

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.
 
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.

Alert level: Severe
This entry was first published on: Feb 08, 2011
This entry was updated on: Apr 17, 2011

This threat is also detected as:
No known aliases