W32.Licum is a file-infecting worm that may spread by exploiting the Microsoft Windows DCOM RPC Interface Buffer Overrun Vulnerability (described in Microsoft Security Bulletin MS03-026).
Also Known As: Backdoor.Win32.Small.gl [Kaspersky Lab], Virus.Win32.Tenga.a [Kaspersky Lab], BackDoor-CTM [McAfee], W32/Gael.worm.a [McAfee], W32/Tenga-A [Sophos], PE_TENGA.A [Trend Micro]
Type: Virus, Worm
Infection Length: 3,072 bytes
Systems Affected: Windows 2000, Windows 95, Windows 98, Windows Me, Windows NT, Windows Server 2003, Windows XP
Virus Definitions (Intelligent Updater) *
July 13, 2005
Virus Definitions (LiveUpdate™) **
July 13, 2005
*
Intelligent Updater definitions are released daily, but require manual download and installation.
Click here to download manually.
**
LiveUpdate virus definitions are usually released every Wednesday.
Click here for instructions on using LiveUpdate.
Wild
Number of infections: 0 - 49
Number of sites: 0 - 2
Geographical distribution: Low
Threat containment: Easy
Removal: Easy
Threat Metrics
Wild:
Low
Damage:
Low
Distribution:
Low
Damage
Payload Trigger: n/a
Payload: May modify executable files.
Large scale e-mailing: n/a
Deletes files: n/a
Modifies files: Modifies other executable files by appending its code.
Degrades performance: May spread by exploiting a vulnerability which may degrade network resources and bandwidth.
Causes system instability: May spread by exploiting a vulnerability which may degrade performance.
Releases confidential info: n/a
Compromises security settings: n/a
Distribution
Subject of email: n/a
Name of attachment: n/a
Size of attachment: n/a
Time stamp of attachment: n/a
Ports: TCP port 139.
Shared drives: n/a
Target of infection: May spread to other computers that are vulnerable to the Microsoft Windows DCOM RPC Interface Buffer Overrun Vulnerability.
When W32.Licum is executed, it performs the following actions:
Downloads the following files:
[http://]utenti.lycos.it/[REMOVED]/dl.exe
[http://]utenti.lycos.it/[REMOVED]/CBACK.EXE
[http://]utenti.lycos.it/[REMOVED]/GAELICUM.EXE
Note: At the time of writing, these files were not available.
Checks for a connection on the vx9.users.freebsd.at domain.
May infect files by appending its code to other executables.
Generates random list of IP addresses and attempts to spread by exploiting the Microsoft Windows DCOM RPC Interface Buffer Overrun Vulnerability (described in Microsoft Security Bulletin MS03-026) through TCP port 139.
Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":
Turn off and remove unneeded services. By default, many operating systems install auxiliary services that are not critical, such as an FTP server, telnet, and a Web server. These services are avenues of attack. If they are removed, blended threats have less avenues of attack and you have fewer services to maintain through patch updates.
If a blended 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 (for example, all Windows-based computers should have the current Service Pack installed.). Additionally, please apply any security updates that are mentioned in this writeup, in trusted Security Bulletins, or on vendor Web sites.
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.
Configure your email server to block or remove email that contains file attachments that are commonly used to spread viruses, such as .vbs, .bat, .exe, .pif and .scr files.
Isolate infected computers quickly to prevent further compromising your organization. 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.
The following instructions pertain to all current and recent Symantec antivirus products, including the Symantec AntiVirus and Norton AntiVirus product lines.
Disable System Restore (Windows Me/XP).
Update the virus definitions.
Run a full system scan and delete all the files detected.
For specific details on each of these steps, read the following instructions.
1. To disable System Restore (Windows Me/XP)
If you are running Windows Me or Windows XP, we recommend that you temporarily turn off System Restore. Windows Me/XP uses this feature, which is enabled by default, to restore the files on your computer in case they become damaged. If a virus, worm, or Trojan infects a computer, System Restore may back up the virus, worm, or Trojan on the computer.
Windows prevents outside programs, including antivirus programs, from modifying System Restore. Therefore, antivirus programs or tools cannot remove threats in the System Restore folder. As a result, System Restore has the potential of restoring an infected file on your computer, even after you have cleaned the infected files from all the other
locations.
Also, a virus scan may detect a threat in the System Restore folder even though you have removed the threat.
For instructions on how to turn off System Restore, read your Windows documentation, or one of the following articles:
How to disable or enable Windows Me System Restore
How to turn off or turn on Windows XP System Restore
Note: When you are completely finished with the removal procedure and are satisfied that the threat has been removed, reenable System Restore by following the instructions in the aforementioned documents.
For additional information, and an alternative to disabling Windows Me System Restore, see the Microsoft Knowledge Base article: Antivirus Tools Cannot Clean Infected Files in the _Restore Folder (Article ID: Q263455).
2. To update the virus definitions
Symantec Security Response fully tests all the virus definitions for quality assurance before they are posted to our servers. There are two ways to obtain the most recent virus definitions:
Running LiveUpdate, which is the easiest way to obtain virus definitions: These virus definitions are posted to the LiveUpdate servers once each week (usually on Wednesdays), unless there is a major virus outbreak. To determine whether definitions for this threat are available by LiveUpdate, refer to Virus Definitions (LiveUpdate).
Downloading the definitions using the Intelligent Updater: The Intelligent Updater virus definitions are posted daily. You should download the definitions from the Symantec Security Response Web site and manually install them. To determine whether definitions for this threat are available by the Intelligent Updater, refer to Virus Definitions (Intelligent Updater).
The latest Intelligent Updater virus definitions can be obtained here: Intelligent Updater virus definitions. For detailed instructions read the document: How to update virus definition files using the Intelligent Updater.
3. To scan for and repair the infected files
Start your Symantec antivirus software and make sure that it is configured to scan all the files.
For Norton AntiVirus consumer products: Read the document, "How to configure Norton AntiVirus to scan all files."
For Symantec AntiVirus Enterprise products: Read the document, "How to verify that a Symantec corporate antivirus product is set to scan all files."
Run a full system scan.
If any files are detected, click Repair.
If any files cannot be repaired, click Delete.
Important: If you are unable to start your Symantec antivirus product or the product reports that it cannot delete a detected file, you may need to stop the risk from running in order to remove it. To do this, run the scan in Safe mode. For instructions, read the document, How to start the computer in Safe Mode. Once you have restarted in Safe mode, run the scan again.
After the files are deleted, restart the computer in Normal mode.
Revision History:
July 17, 2005: Added alias information.
Write-up by: Jeong Mun and Candid Wueest
最关键还是你没打好系统补丁～～～～｀｀｀
