Discovered: July 12, 2002
Updated: February 13, 2007 11:53:14 AM
Also Known As: Trojan.Win32.Rewin [AVP], TROJ_REWIN.A [Trend], Troj/QDel197 [Sophos], Perniw [McAfee]
Type: Trojan Horse
Systems Affected: Windows


W32.Rewin is a Trojan horse that is designed to spread through floppy disks. This Trojan deletes specific files from an infected computer. It is written in the Microsoft Visual Basic programming language.

Antivirus Protection Dates

  • Initial Rapid Release version July 12, 2002
  • Latest Rapid Release version September 28, 2010 revision 054
  • Initial Daily Certified version July 12, 2002
  • Latest Daily Certified version September 28, 2010 revision 036
  • Initial Weekly Certified release date July 15, 2002

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

Writeup By: Yana Liu

Discovered: July 12, 2002
Updated: February 13, 2007 11:53:14 AM
Also Known As: Trojan.Win32.Rewin [AVP], TROJ_REWIN.A [Trend], Troj/QDel197 [Sophos], Perniw [McAfee]
Type: Trojan Horse
Systems Affected: Windows


When W32.Rewin runs, it does the following:

It copies itself as

  • A:\Kernel.exe
  • C:\%windir%\Winrep.com
  • C:\%system%\Dialer.com

NOTES:
  • %windir% is a variable. The worm locates the \Windows folder (by default this is C:\Windows or C:\Winnt) and copies itself to that location.
  • %system% is a variable. The worm locates the \Windows\System folder (by default this is C:\Windows\System or C:\Winnt\System32) and copies itself to that location.

It then adds the values

Win32RG C:\%windir%\winrep.com
Win32RG C:\%system%\Dialer.com

to the registry key

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run

so that the Trojan runs when you start Windows.

The Trojan creates the text file C:\Hackers.txt. This file is not viral and, therefore, is not detected by Symantec antivirus products. Delete this text file manually if the computer is infected with W32.Rewin.

The Trojan then attempts to delete all files in the following folders and drives:
  • C:\Archivos de programa
  • C:\Mis documentos
  • C:\Program Files
  • Drives D, E, F, G, and H


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: Yana Liu

Discovered: July 12, 2002
Updated: February 13, 2007 11:53:14 AM
Also Known As: Trojan.Win32.Rewin [AVP], TROJ_REWIN.A [Trend], Troj/QDel197 [Sophos], Perniw [McAfee]
Type: Trojan Horse
Systems Affected: Windows


Update the virus definitions, run a full system scan, and delete all files that are detected as W32.Rewin. Also delete C:\Hackers.txt.

  1. Delete the values

    Win32RG C:\%windir%\winrep.com
    Win32RG C:\%system%\Dialer.com

    from the registry key

    HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run

For details on how to do this, read the following instructions.

To scan for and delete the infected files:
  1. Obtain the most recent virus definitions. There are two ways to do this:
    • Run LiveUpdate, which is the easiest way to obtain virus definitions. These virus definitions have undergone full quality assurance testing by Symantec Security Response and are posted to the LiveUpdate servers one time each week (usually Wednesdays) unless there is a major virus outbreak. To determine whether definitions for this threat are available by LiveUpdate, look at the Virus Definitions (LiveUpdate) line at the top of this write-up.
    • Download the definitions using the Intelligent Updater. Intelligent Updater virus definitions have undergone full quality assurance testing by Symantec Security Response. They are posted on U.S. business days (Monday through Friday). They must be downloaded from the Symantec Security Response Web site and installed manually. To determine whether definitions for this threat are available by the Intelligent Updater, look at the Virus Definitions (Intelligent Updater) line at the top of this write-up.

      Intelligent Updater virus definitions are available here. For detailed instructions on how to download and install the Intelligent Updater virus definitions from the Symantec Security Response Web site, click here.
  2. Start your Symantec antivirus program, and make sure that it is configured to scan all files.
  3. Run a full system scan.
  4. If any files are detected as infected by W32.Rewin, click Delete. Replace from a clean backup the files that the Trojan deleted, or reinstall them.
  5. Using Windows Explorer, locate and delete C:\Hackers.txt.

To remove the value from the registry:

CAUTION : Symantec strongly recommends that you back up the registry before you make any changes to it. Incorrect changes to the registry can result in permanent data loss or corrupted files. Modify only the keys that are specified. Read the document How to make a backup of the Windows registry for instructions.
  1. Click Start, and click Run. The Run dialog box appears.
  2. Type regedit and then click OK. The Registry Editor opens.
  3. Navigate to the following key:

    HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
  4. In the right pane, delete the following values:

    Win32RG      C:\%System%\Dialer.com
    Win32RG      C:\%Windir%\Winrep.com
  5. Exit the Windows registry.


Writeup By: Yana Liu