Win32/Pameseg is a family of installers that require the user to send an SMS message to a premium number to successfully install certain programs, some of which are otherwise be available for free. Currently, most variants target Russian speakers.

For more information on Pameseg, please see the following blog posts:

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 detect and remove this threat:

For more information on antivirus software, see

Threat behavior

Win32/Pameseg is a family of installers that require the user to send an SMS message to a premium number to successfully install certain programs, some of which are otherwise be available for free. Currently, variants of Pameseg target Russian speakers.

The installer claims that when users send the SMS message, they receive a code used to complete installation of the program. However, this has not been verified.

Win32/Pameseg usually claims to be an installer for certain types of programs, which usually fall under the following categories (note that this list is not exhaustive):

  • Key generators
  • Password recovery tools
  • Pirated games and game cheat codes
  • Pirated Microsoft products
  • Social networking plugins

In the wild, Pameseg has been seen to contain the following software:

Adobe Flash Player
Adobe Reader
ALAWAR Keygen 2011
Aluminum WMP
DjVu Solo
DrWeb Anti-virus
GTA SA Mega Chat Pack
Kaspersky Internet Security
Media Player Classic
Microsoft DirectX
Microsoft FrontPage
Mirabilis ICQ
Mozilla Firefox
NOD32 Anti-virus
QIP 2005
Rambler ICQ 7
STDU Viewer
Windows update patch
Word 2007

The installer may appear similar to any of the following:

The installer is usually created using ZipMonster, an application that allows the installer to be packaged with different user interfaces so that it may look as close to the original installer as possible.

Aside from payment via SMS messages, users can also pay using web-based payment services such as Webmoney, PayPal, or credit cards. Note that these services are legitimate but are being used with malicious intent by Pameseg.


For more information on Pameseg, please see the following blog posts:


Additional information 

April 2013: We have realigned over a hundred signatures related to the Pameseg family name and reclassified them from Program to Trojan. This research identified the following new families:

  • Trojan:Win32/Zonsterarch
  • Trojan:Win32/Blinerarch
  • Trojan:Win32/Ninunarch
  • Trojan:Win32/Tarifarch
  • Trojan:Win32/Zipparch
  • Trojan:Win32/Multsarch
  • Trojan:Win32/Smasarch
  • Trojan:Win32/Movivarch  
  • Trojan:Win32/Ziconarch
  • Trojan:Win32/Moxtrarch  
  • Trojan:Win32/Instonarch
  • Trojan:Win32/Nadostarch
  • Trojan:Win32/Mobsularch

Analysis by Jaime Wong and Methusela Cebrian Ferrer


System changes

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

  • When trying to install a program, you are prompted by the installer to send payment via SMS or another web-based payment service.
  • The installer appears similar to the following:






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

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

Alert level: Severe
This entry was first published on: Feb 08, 2012
This entry was updated on: Apr 22, 2013

This threat is also detected as:
  • Win32/Zonsterarch (other)
  • Win32/Blinerarch (other)
  • Win32/Ninunarch (other)
  • Win32/Tarifarch (other)
  • Win32/Zipparch (other)
  • Win32/Multsarch (other)
  • Win32/Smasarch (other)
  • Win32/Movivarch (other)
  • Win32/Ziconarch (other)
  • Win32/Moxtrarch (other)
  • Win32/Instonarch (other)
  • Win32/Nadostarch (other)
  • Win32/Mobsularch (other)