W32.SillyIM

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Discovered: July 14, 2005
Updated: April 27, 2010 4:50:11 PM
Type: Worm
Systems Affected: Windows

W32.SillyIM is a detection name used by Symantec that detects variants of the W32.Silly family of worms that spread using instant messaging applications.

Instant Messaging (IM) is real-time communication and is popularly known as chat. Instant Messaging, as its name implies, allows a user to type and send a message to another IM user on another computer anywhere else in the world and have it viewed in real-time. As soon as a user presses the Enter key, the message is instantly broadcast to all intended recipients.

When an instant messaging worm is downloaded, it usually sends itself to all other active users in the friend list of the compromised computer. In this way, a friend of the initial recipient of the worm will receive a message from someone they know and unknowingly accept the worm on to their computer, thus propagating the worm even further.

Antivirus Protection Dates

  • Initial Rapid Release version July 14, 2005
  • Latest Rapid Release version November 11, 2018 revision 023
  • Initial Daily Certified version July 14, 2005 revision 007
  • Latest Daily Certified version November 12, 2018 revision 002
  • Initial Weekly Certified release date July 20, 2005

Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.

Writeup By: Éamonn Young

Discovered: July 14, 2005
Updated: April 27, 2010 4:50:11 PM
Type: Worm
Systems Affected: Windows

Background information
Instant Messaging (IM) is real-time communication and is popularly known as chat. Instant Messaging, as its name implies, allows a user to type and send a message to another IM user on another computer anywhere else in the world and have it viewed in real-time. As soon as a user presses the Enter key, the message is instantly broadcast to all intended recipients.

The following is a list of some popular IM clients:

  • AIM
  • Google Talk
  • ICQ
  • MSN Messenger
  • Windows Live Messenger
  • Yahoo! Instant Messenger


Most IM applications allow a user to have a friend list, which is comprised of several people that the user wishes to communicate with. Communication can be done in a private one-to-one fashion, or as a public chat.

All IM clients provide chat functionality, but some versions also allow file-sharing and webcams.

Furthermore, many mobile networks also provide the ability to send instant messages to wireless PDAs and cell phones.


Who creates instant messaging worms?
Mostly, this type of worm is created in order to spread to as many computers as possible. Malware authors may use IM as a way to communicate with each other or as a way to communicate with the malware, which they have created.

Furthermore, malware authors often use IM worms to drop more malware on to a compromised computer.


What happens after the worm is installed?
When an IM worm is downloaded, it usually sends a copy of itself to all other active users in the friend list of the compromised computer. In this way, a friend of the initial recipient of the worm will receive a message from someone they know and unknowingly accept the worm on to their computer, thus propagating the worm even further.


What can the worm do?
The primary purpose of a worm is to spread itself. Worms often use social engineering techniques in order to spread from one computer to another. Worms that spread through IM applications usually send a simple, generic message and include a location where the worm can be downloaded from, for example, a link to a website or an attached .zip file.

However, depending on how malicious the author is and how devastating their intentions, a worm can perform any number of malicious activities on the compromised computer, including:
  • Disable security-related programs
  • Download files
  • Drop more malware
  • Open a back door
  • Steal information


Are there any tell-tale signs?
Many of the worms that spread through IM applications invite a user to view pictures or visit a funny link, for example:
  • hey man accept my pics
  • Hehe, check this out :-)
  • LOL!! See this :D
  • Hehe, this is fun :-)


These message include a link to a location where the worm can be downloaded from. The messages can be quite generic and simple. If unsure of the source of the message or if the message is unexpected, a user should always exercise caution when clicking on the link provided.

Furthermore, many IM worms can send messages in several languages. The worm has the capability to detect the language settings on a computer and send a message appropriate to the language being used.


What are the risks?
The damage that can be inflicted by a worm varies. Sometimes worms can spread quite slowly, depending on user activity. Other times, worms can cause very heavy network traffic and prove to be very disruptive. As previously discussed, worms may also include additional functionality that may harm the compromised computer further.


What can I do to minimize the risks?
Users should use discretion when clicking on links from known or unknown senders. Avoid following URLs sent along with generic messages.


How can I find out more?
Advanced users can submit a sample to Threat Expert to obtain a detailed report of the system and file system changes caused by a threat.

Recommendations

Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":

  • Use a firewall to block all incoming connections from the Internet to services that should not be publicly available. By default, you should deny all incoming connections and only allow services you explicitly want to offer to the outside world.
  • Enforce a password policy. Complex passwords make it difficult to crack password files on compromised computers. This helps to prevent or limit damage when a computer is compromised.
  • Ensure that programs and users of the computer use the lowest level of privileges necessary to complete a task. When prompted for a root or UAC password, ensure that the program asking for administration-level access is a legitimate application.
  • Disable AutoPlay to prevent the automatic launching of executable files on network and removable drives, and disconnect the drives when not required. If write access is not required, enable read-only mode if the option is available.
  • Turn off file sharing if not needed. If file sharing is required, use ACLs and password protection to limit access. Disable anonymous access to shared folders. Grant access only to user accounts with strong passwords to folders that must be shared.
  • Turn off and remove unnecessary services. By default, many operating systems install auxiliary services that are not critical. These services are avenues of attack. If they are removed, threats have less avenues of attack.
  • If a threat exploits one or more network services, disable, or block access to, those services until a patch is applied.
  • Always keep your patch levels up-to-date, especially on computers that host public services and are accessible through the firewall, such as HTTP, FTP, mail, and DNS services.
  • Configure your email server to block or remove email that contains file attachments that are commonly used to spread threats, such as .vbs, .bat, .exe, .pif and .scr files.
  • Isolate compromised computers quickly to prevent threats from spreading further. Perform a forensic analysis and restore the computers using trusted media.
  • Train employees not to open attachments unless they are expecting them. Also, do not execute software that is downloaded from the Internet unless it has been scanned for viruses. Simply visiting a compromised Web site can cause infection if certain browser vulnerabilities are not patched.
  • If Bluetooth is not required for mobile devices, it should be turned off. If you require its use, ensure that the device's visibility is set to "Hidden" so that it cannot be scanned by other Bluetooth devices. If device pairing must be used, ensure that all devices are set to "Unauthorized", requiring authorization for each connection request. Do not accept applications that are unsigned or sent from unknown sources.
  • For further information on the terms used in this document, please refer to the Security Response glossary.

Writeup By: Éamonn Young

Discovered: July 14, 2005
Updated: April 27, 2010 4:50:11 PM
Type: Worm
Systems Affected: Windows

You may have arrived at this page either because you have been alerted by your Symantec product about this risk, or you are concerned that your computer has been affected by this risk.

Before proceeding further we recommend that you run a full system scan . If that does not resolve the problem you can try one of the options available below.



FOR NORTON USERS
If you are a Norton product user, we recommend you try the following resources to remove this risk.

Removal Tool


If you have an infected Windows system file, you may need to replace them using from the Windows installation CD .


How to reduce the risk of infection
The following resources provide further information and best practices to help reduce the risk of infection.


FOR BUSINESS USERS
If you are a Symantec business product user, we recommend you try the following resources to remove this risk.

Identifying and submitting suspect files
Submitting suspicious files to Symantec allows us to ensure that our protection capabilities keep up with the ever-changing threat landscape. Submitted files are analyzed by Symantec Security Response and, where necessary, updated definitions are immediately distributed through LiveUpdate™ to all Symantec end points. This ensures that other computers nearby are protected from attack. The following resources may help in identifying suspicious files for submission to Symantec.


Removal Tool

If you have an infected Windows system file, you may need to replace them using from the Windows installation CD .


How to reduce the risk of infection
The following resource provides further information and best practices to help reduce the risk of infection.
Protecting your business network



MANUAL REMOVAL
The following instructions pertain to all current Symantec antivirus products.

1. Performing a full system scan
How to run a full system scan using your Symantec product


2. Restoring settings in the registry
Many risks make modifications to the registry, which could impact the functionality or performance of the compromised computer. While many of these modifications can be restored through various Windows components, it may be necessary to edit the registry. See in the Technical Details of this writeup for information about which registry keys were created or modified. Delete registry subkeys and entries created by the risk and return all modified registry entries to their previous values.

Writeup By: Éamonn Young