W32.HLLW.Oror.AI@mm

SUMMARY

W32.HLLW.Oror.AI@mm is a variant of the W32.HLLW.Oror@mm mass-mailing worm. This worm attempts to spread using email, mIRC, KaZaA, network shares, and mapped drives. The email attachment arrives with a .exe or .scr file extension. W32.HLLW.Oror.AI@mm also attempts to terminate and remove various security products from the infected computer.

This threat is written in the C++ language. Some of the files are compressed with UPX.

Protection

• Virus Definitions (LiveUpdate™ Weekly) March 19, 2003
• Virus Definitions (Intelligent Updater) March 14, 2003

Threat Assessment

Wild

• Wild Level: Low
• Number of Infections: 0 - 49
• Number of Sites: 0 - 2
• Geographical Distribution: Low
• Threat Containment: Easy
• Removal: Moderate

Damage

• Damage Level: High
• Large Scale E-mailing: Emails itself to all the email addresses gathered from incoming email messages already present on the infected computer
• Deletes Files: Attempts to delete all the files on the system
• Compromises Security Settings: Attempts to terminate and remove various security products from the infected computer

Distribution

• Distribution Level: High
• Subject of Email: Varies
• Name of Attachment: Varies with the .exe or .scr file extension
• Size of Attachment: Varies
• Ports: Tries to spread using IRC
• Shared Drives: Network shares and mapped drives

TECHNICAL DETAILS

W32.HLLW.Oror.AI@mm is similar to W32.HLLW.Oror@mm and its B and C variants. W32.HLLW.Oror.AI@mm does not seem to contain any new email messages that are not present in the older variants of this worm. W32.HLLW.Oror.AI@mm is a product of recompiling the B variant with some changed messages from the A and C variants. The purpose of the author of this worm must have been to quickly make a new version of the worm that is harder to detect with existing antivirus software.

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 this worm, read the removal instructions in the W32.HLLW.Oror.C@mm writeup.