AOL.Trojan

SUMMARY

AOL.Trojan is a generic detection for a group of Trojans that are made specifically to work under America Online. Some variants of this Trojan might also open ports to allow a hacker to gain access to the infected system.

Protection

• Virus Definitions (Intelligent Updater) December 11, 1997

Threat Assessment

Wild

• Wild Level: Medium
• Number of Infections: More than 1000
• Number of Sites: More than 10
• Geographical Distribution: High
• Threat Containment: Easy
• Removal: Easy

Damage

• Damage Level: Low

Distribution

• Distribution Level: Low

TECHNICAL DETAILS

If AOL.Trojan is executed, it is possible for a hacker to perform any of the following actions:

• Reboot or shut down the computer
• Move the mouse pointer
• Enable and disable Ctrl+Alt+Delete
• Enable and disable the Start button
• Open or close the CD-ROM drive tray
• Read or delete AOL mail
• Hide or show the task bar
• Locate a member on AOL
• Monitor AOL Instant Messages
• Send a Instant Message

Most of these AOL Trojans are written in Visual Basic, which will not run on systems that do not have the Visual Basic run time libraries. Also, most of these AOL Trojans create copies of themselves in the following folders:

• Windows
• WindowsSystem

In most cases, the Trojan creates a registry value in one or more of these registry keys:

HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionRun
HKEY_CURRENT_USERSOFTWAREMicrosoftWindowsCurrentVersionRun
HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionRunServices

These registry keys are common loading points to make sure that the Trojan is run when you start Windows.

Some also add lines to the Win.ini file or the System.ini file so that they run at startup; this works only under Windows 95/98/Me.

For information about common loading points, read one of these documents:

• Common loading points of threats in Windows NT/2000/XP
• Common loading points of threats in Windows 95/98/Me

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

1. Run LiveUpdate to make sure that you have the most recent virus definitions.
2. Start Norton AntiVirus (NAV), and make sure that NAV is configured to scan all files. For instructions on how to do this, read the document How to configure Norton AntiVirus to scan all files.
3. Run a full system scan. Delete all files that are infected with AOL.Trojan.
4. Remove any references (to the infected files) that were added to the Windows registry.
5. (Windows 95/98/Me only) Remove any references to the infected files that were added to the Win.ini and System.ini files.