W32.Apost.Worm@mm

SUMMARY

NOTE: The worm was previously known as W32.Urgent.worm@mm. Due to a decrease in submissions, the threat level has been downgraded from 3 to 2.

This worm is a Visual Basic Application that arrives as the attachment Readme.exe. It requires the Microsoft Visual Basic Runtime Libraries to replicate.

The body of the email asks the recipient to review the attachment, but after it has been viewed it copies itself to the system and spreads itself to everyone in the Microsoft Outlook address book.

Protection

• Virus Definitions (LiveUpdate™ Weekly) September 4, 2001
• Virus Definitions (Intelligent Updater) September 4, 2001

Threat Assessment

Wild

• Wild Level: Low
• Number of Infections: 50 - 999
• Number of Sites: More than 10
• Geographical Distribution: Low
• Threat Containment: Easy
• Removal: Moderate

Damage

• Damage Level: Low
• Large Scale E-mailing: emails to all contacts in your address book

Distribution

• Distribution Level: High
• Subject of Email: As per you request!
• Name of Attachment: readme.exe
• Size of Attachment: 24,576 bytes

TECHNICAL DETAILS

This worm arrives as an email message in the following format:

Subject: As per your request!
Message: Please find attached file for your review. I look forward to hear from you again very soon.  Thank you.
Attachment: Readme.exe

If the Readme.exe file is executed, the worm performs the following actions:

1. It creates a copy of itself in the Windows folder, as Readme.exe.
2. It then creates the value
   
   macrosoft    C:Windowseadme.exe
   
   in the registry key
   
   HKEY_CURRENT_USERSoftwareMicrosoft
   WindowsCurrentVersionRun
   
   so that the worm runs each time that you start Windows.
   
3. The worm then writes a copy of itself into the root of all drives (this includes floppy drives, Zip drives, and network drives).
4. It emails itself to all the contacts in the Microsoft Outlook address book.
5. It then displays the message:
   
   
   
   and waits for you to click Open. When you click Open, it repeats the previously mentioned steps and then displays the following fake error message:
   
   
   
6. It then quits.

NOTE: Because this worm activates its insertion and emailing routine twice, a recipient will likely will get at least two emails with this worm as an attachment.

Recommendations

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.

REMOVAL

To remove the worm, delete files that are detected as W32.Apost.Worm@mm and remove the registry entry that it added.

To remove the worm:

1. Run LiveUpdate to make sure that you have the most recent virus definitions.
2. Start Norton AntiVirus (NAV), and run a full system scan. Be sure that NAV is configured to scan all files.
3. Delete all files that are detected as W32.Apost.Worm@mm.

To edit the registry:

CAUTION: We strongly recommend that you back up the system registry before you make any changes. Incorrect changes to the registry could result in permanent data loss or corrupted files. Please make sure that you modify only the keys that are specified. Please see the document How to back up the Windows registry before you proceed.

1. Navigate to and select the following key:
   
   HKEY_CURRENT_USERSoftwareMicrosoft
   WindowsCurrentVersionRun
   
2. In the right pane, look for and select the value
   
   macrosoft     C:Windowseadme.exe
   
3. Press Delete, and then click Yes to confirm.
4. Exit the Registry Editor.