Win32/Gamarue is a family of malware that may be distributed by exploit kits, spammed emails or other malware, and has been observed stealing information from an affected user.

Win32/Gamarue is a family of malware that may be distributed by exploit kits, spammed emails or other malware, and has been observed stealing information from an affected user.

Installation

Win32/Gamarue has been observed to be distributed via exploit kits (for example, Blacole), spammed emails (for example, emails with the subject 'Your ex sent me this pciture [sic] of you.', and an attachment named 'Photo.zip'), and other malware (for example, Win32/Dofoil and Win32/Beebone).

When executed, Win32/Gamarue creates a new instance of one of the following files, and injects its payload into the new process:

• %SystemRoot%\system32\svchost.exe
• %SystemRoot%\system32\wuauclt.exe

If Win32/Gamarue runs with administrator privileges, it may copy itself to the following folders:

• %USERPROFILE%\Local Settings\Temp
• %ALLUSERSPROFILE%\Local Settings\Temp

The file it copies to these folders has a random file name, and uses one of the following file extensions:

• .bat
• .cmd
• .com
• .exe
• .pif
• .scr

Depending on whether the malware runs with administrator privileges, it may create the following registry entries to ensure its execution at each Windows start:

In subkey: HKCU\Software\Microsoft\Windows NT\CurrentVersion\Windows\
Sets value: "load"
With data: "<malware file name>"

In subkey: HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\Explorer\Run\
Sets value: "<random value>"
With data: "<malware file name>"

Payload

Steals sensitive information

Win32/Gamarue has been observed stealing the following information from an affected computer:

• Operating system information
• Local IP address
• Root volume serial number
• Level of privilege, for example, administrator privilege

Contacts remote hosts

Win32/Gamarue reports back to a command and control (C&C) server to report back any stole information; it then waits for further commands.

In the wild, we ave observed Gamarue contacting the following remote hosts:

• zaletelly06.be
• zaletelly07.be
• napasaran.ru
• loshatemikontara551.ru
• serioslyf<removed>ked.ru

Depending on the commands received, an attacker can perform any number of different actions on an affected computer using Gamarue; this may include, but is not limited to, the following actions:

• Download and execute additional files; downloaded files may be dropped to the %TEMP% folder
• Download and execute additional components, which are executed each time the malware runs, and stored in:
• HKLM\SOFTWARE\Microsoft\ <random>
• HKCU\SOFTWARE\Microsoft\ <random>
• Update itself
• Uninstall itself

Analysis by Shawn Wang

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.

• How to turn on the Windows Firewall in Windows 7
• How to turn on the Windows Firewall in Windows Vista
• How to turn on the Windows firewall in Windows XP

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:

• Microsoft Malware Protection Center - Updating Software

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.

• How to turn on Automatic Updates in Windows 7
• How to turn on Automatic Updates in Windows Vista
• How to turn on Automatic Updates in Windows XP

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:

• User Account Control in Windows 7
• User Account Control in Windows Vista
• Applying the Principle of Least Privilege in Windows XP
• More on User Account Control

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/security/online-privacy/passwords-create.aspx.

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:

• Microsoft Security Essentials
• Microsoft Safety Scanner
• Microsoft Windows Malicious Software Removal Tool

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