JS.Exception.Exploit

Printer Friendly Page

Discovered: August 16, 2001
Updated: February 13, 2007 12:01:12 PM
Type: Trojan Horse
Systems Affected: Windows
CVE References: CVE-2000-1061


JS.Exception.Exploit is a detection for an exploit that allows Java applets to perform various actions on your system if you are using an older or unpatched version of Microsoft Internet Explorer.

In many cases, JS.Exception.Exploit may perform simple actions such as changing your Internet Explorer home page. (This is one of the most common uses of this exploit.) It has been reported, but not confirmed, that some adware programs use JS.Exception.Exploit to do this. As a result, your Symantec antivirus program may detect JS.Exception.Exploit when the adware program displays a pop-up ad that uses the exploit.

IMPORTANT:
If your Symantec antivirus program alerts you to JS.Exception.Exploit, this means that it has stopped the exploit and prevented it from running. It does not mean that your computer is "infected" with this threat. Rather, it means that the antivirus program has stopped it. Because the exploit is usually not on your computer, in most cases you will not be able to "delete" it, since there is nothing to delete.

To be sure that your computer is free of currently-known threats, we suggest that you run LiveUpdate and then run a full system scan.

If you continue to receive alerts when pop-up ads are displayed, you need to determine what adware you have installed on your computer, then disable or remove it. You may need to contact your computer vendor for assistance in identifying and disabling advertising software. You can also obtain and run programs that are designed to detect and remove adware.

Antivirus Protection Dates

  • Initial Rapid Release version August 20, 2001
  • Latest Rapid Release version May 09, 2018 revision 037
  • Initial Daily Certified version August 20, 2001
  • Latest Daily Certified version May 10, 2018 revision 001
  • Initial Weekly Certified release date August 20, 2001

Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.

Writeup By: Patrick Nolan

Discovered: August 16, 2001
Updated: February 13, 2007 12:01:12 PM
Type: Trojan Horse
Systems Affected: Windows
CVE References: CVE-2000-1061


The structure of the code is specific and involves the illegal use of the <Applet> tag. The exploit was published in at least one security forum. More information about this vulnerability is available at Microsoft's Technet site:

http://www.microsoft.com/technet/treeview/default.asp?url=/TechNet/security/bulletin/ms00-075.asp

Although JS.Exception.Exploit may perform simple actions, such as changing your Internet Explorer home page, it can also be programmed to perform actions such as a mass mailing, as in the case of VBS.Loding.A@mm , or to create file on your computer that performs almost any malicious action.

Detections of JS.Exception.Exploit when visiting a Web site
When you visit a JS.Exception.Exploit Web site, the exploit is detected by Symantec antivirus products, usually in a temporary Internet file. The antivirus program then reports that it cannot repair, quarantine, or even delete the file. This may happen more than once until you close the Web site. If you then run a scan, it may find no instances of JS.Exception.Exploit .

The reason for this is that your Symantec antivirus program is detecting the exploit itself. Your Symantec antivirus program detects it when scanned by Auto-Protect as it is copied to the Temporary Internet Files folder. Because these temporary files may be deleted as soon as you close the Web page, the exploit will not be found during a regular scan because it is no longer there. Also, because it is the exploit itself that is being detected, it will be detected even if you are using a patched system or another Web browser.

NOTE: Because Temporary Internet Files are not always deleted after you close a Web site, (this depends on you Web browser's settings), we suggest that you close all Web browser windows before running a full system scan. This prevents the Temporary Internet Files from being "in use" by Windows in the event that one is found to be infected when running the scan.

Microsoft patch
Microsoft has released a patch that removes the security vulnerability. You can download the patch from the following Microsoft site:

http://www.microsoft.com/technet/treeview/default.asp?url=/TechNet/security/bulletin/ms00-081.asp

What is an exploit, and what can JS.Exception.Exploit do?
An exploit is code that takes advantage of a security hole in a program or the operating system. You can think of it as a key to a locked door. If the door is open, almost anything can come in. JS.Exception.Exploit can by programmed to do almost anything on an unpatched system, such as:

  • Copy and run a virus, worm, or Trojan
  • Create and run a file that sends information to a hacker
  • Change your Internet Explorer home page (This is the most common use of JS.Exception.Exploit.)


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: Patrick Nolan

Discovered: August 16, 2001
Updated: February 13, 2007 12:01:12 PM
Type: Trojan Horse
Systems Affected: Windows
CVE References: CVE-2000-1061


The following instructions pertain to all current and recent Symantec antivirus products, including the Symantec AntiVirus and Norton AntiVirus product lines.

  1. Update the virus definitions.
  2. Run a full system scan and delete all the files detected as JS.Exception.Exploit.
  3. Delete the value that was added to the registry.
For specific details on each of these steps, read the following instructions.

IMPORTANT NOTES. PLEASE READ BEFORE YOU CONTINUE:
  • These are general removal instructions for the most commonly distributed variant of JS.Exception.Exploit. If JS.Exception.Exploit has run on an unpatched system that did not have current virus definitions, other registry values or keys may have been changed or added and files may have been copied to your system. These instructions will reverse the most common changes. If you need assistance, please obtain the services of a qualified virus removal or computer consultant.
  • Several cases have been reported in which JS.Exception.Exploit was received in a compressed file. (This has not been confirmed by Symantec Security Response.) In general, while Symantec antivirus products will detect an infected file that is contained within a compressed file, by design it cannot extract or remove it. If you receive an alert for this or any threat on a compressed file (such as a .zip file) we recommend that you simply delete the compressed file using Windows Explorer.
  • Removal is only necessary if you detect this threat after it has actually run and made changes to your system. (You can confirm this by disconnecting from the Web and then running a full system scan. If nothing is found during a full system scan, your computer is not infected.
  1. Update the virus definitions.
  2. Run a full system scan, and delete all files that are detected as JS.Exception.Exploit.
  3. In the registry key

    HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main

    examine the text in the Data column for these values:

    Start Page
    Search Page
    Default_Page_URL
    Default_Search_URL
  4. If any refer to a suspicious address (for example, http:/ /jethomepage.com), clear the value data.
For details on how to do this, read the following instructions.

1. Updating 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 the Virus Definitions (LiveUpdate).
    • Downloading the definitions using the Intelligent Updater. The Intelligent Updater virus definitions are posted on U.S. business days (Monday through Friday). 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 the Virus Definitions (Intelligent Updater).

      The Intelligent Updater virus definitions are available. Read "How to update virus definition files using the Intelligent Updater" for detailed instructions.

2. Scanning for and deleting the infected files
3. Deleting the value from the registry

CAUTION : Symantec strongly recommends that you back up the registry before you make any changes to it. Incorrect changes to the registry can result in permanent data loss or corrupted files. Modify the specified keys only. Read the document, "How to make a backup of the Windows registry ," for instructions.
  1. Click Start, and then click Run. (The Run dialog box appears.)
  2. Type regedit

    Then click OK. (The Registry Editor opens.)
  3. Navigate to the key:

    HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
  4. In the right pane look for the following values:

    Start Page
    Search Page
    Default_Page_URL
    Default_Search_URL
  5. For each one that you find, double-click the value. The Edit String dialog box appears.
  6. If the text in the Value data box points to a suspicious Web page, such as the http:/ /jethomepage.com value that appears in this graphic:



    then delete all of the text in the Value data box, as shown here:


  7. Click OK. (It is not necessary to enter anything in the box.)
  8. After you have done this for all of the values mentioned in step 4, click Registry, and click Exit.


Writeup By: Patrick Nolan