1. Symantec/
  2. Security Response/
  3. W32.Looksky.G@mm

W32.Looksky.G@mm

Risk Level 2: Low

Discovered:
January 8, 2006
Updated:
February 13, 2007 12:50:31 PM
Also Known As:
WORM_LOCKSKY.AB [Trend Micro], WORM_LOCKSKY.AL [Trend Micro]
Type:
Worm
Systems Affected:
Windows

Once executed, W32.Looksky.G@mm performs the following actions:
  1. Copies itself as the following files:

    • %Windir%\sachostx.exe
    • %CurrentFolder%\temp.bak

      Notes:
    • %Windir% is a variable that refers to the Windows installation folder. By default, this is C:\Windows or C:\Winnt.
    • %CurrentFolder% is a variable that refers to the folder where the risk was originally executed.

  2. Drops the following additional files:

    • %System%\attrib.ini (a file to store stolen information)
    • %System%\hard.lck (a zero-byte file that is not malicious)
    • %System%\msvcrl.dll (a keylogger component that is a copy of W32.Looksky.A@mm)
    • %System%\sachostc.exe (a proxy server)
    • %System%\sachostp.exe (a component that steals compromised system information, email usernames, and passwords)
    • %System%\sachosts.exe (an HTTP proxy server)
    • %System%\sachostw.exe (a mass-mailer component that is a copy of W32.Looksky.F@mm)
    • %System%\sachostb.exe (a back door component)

      Note: %System% is a variable that refers to the System folder. By default this is C:\Windows\System (Windows 95/98/Me), C:\Winnt\System32 (Windows NT/2000), or C:\Windows\System32 (Windows XP).

  3. Adds the value:

    "HostSrv" = "%Windir%\sachostx.exe"

    to the registry subkey

    HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run

    so that it runs every time Windows starts.

  4. Runs netsh.exe in the following usage in an attempt to bypass the firewall settings on the compromised computer for all the above files:

    netsh firewall set allowedprogram [WORM FILE NAME] enable

  5. Creates registry entries under the following subkey:

    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess
    \Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List


    to modify firewall settings and lower security settings.

  6. Opens a back door and allows a remote attacker to perform unauthorized actions on the compromised computer.

  7. Logs keystrokes and may steal confidential information from the compromised computer.

  8. Operates as a covert proxy.

  9. Updates itself by downloading the following files:

    • [http://]proxy4u.ws:8080/[REMOVED]/download.exe
    • [http://]proxy4u.ws:8080/[REMOVED]/update.htm
    • [http://]usproxy2u.ws:8080/[REMOVED]/download.exe
    • [http://]usproxy2u.ws:8080/[REMOVED]/update.htm

  10. Saves the above files as:

    %TEMP%\tmx[RANDOM CHARACTERS].exe

    Note: %Temp% is a variable that refers to the Windows temporary folder. By default, this is C:\Windows\TEMP (Windows 95/98/Me/XP) or C:\WINNT\Temp (Windows NT/2000).

  11. Posts local system information to the following location:

    [http://]proxy4u.ws/[REMOVED]

  12. Gathers email addresses from the Windows Address Book and .htm files. It then sends out a copy of itself as an email attachment. The email has the following characteristics:

    Subject: Your mail Account is Suspended

    Message Body:
    We regret to inform you that your account has been suspended due to the violation of our site policy, more info is attached.

    Attachment:
    One of the following:

    • acc_info9.exe
    • ebay_info.exe
    • acc_inf19.exe


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: Candid Wueest
Summary| Technical Details| Removal

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