Downloader.Ject

SUMMARY

Downloader.Ject is a Trojan horse that attempts to download and install a file by exploiting the vulnerabilities in Internet Explorer (BID 10472, BID 10473). The Trojan is triggered by visiting a Web site that contains the exploit code.

For additional information, read the Microsoft Internet Knowledge Base article Information Services (IIS) 5.0 – Download.Ject Detection and Recovery Advisory (Article 871277).

Microsoft has released a configuration change to protect against this threat. For more information, read the article What You Should Know About Download.Ject.

This vulnerability was originally reported on June 6, 2004. Refer to http://securityfocus.com/archive/1/365293 for additional information.

The Microsoft update that fixes this vulnerability is described in Microsoft Security Bulletin MS04-025. Cumulative Security Update for Internet Explorer (Article 867801).

Note: Virus definitions dated prior to June 16, 2004, may detect this threat as Bloodhound.Exploit.10.

Note: Virus definitions dated June 7th, 2006 or earlier may detect this threat as Download.Ject.

Protection

• Virus Definitions (LiveUpdate™ Weekly) June 16, 2004
• Virus Definitions (Intelligent Updater) June 16, 2004

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

Distribution

• Distribution Level: Low

TECHNICAL DETAILS

Downloader.Ject attempts to download and execute a file using the cross-zone scripting exploit in Internet Explorer, with redirection and delayed script injection, through a modal dialog box.

As this notification was written, Downloader.Ject attempts to download and install an adware component. Symantec antivirus products, which support security risk detection, detect this adware as Adware.VirtuMonde. The file is downloaded to C:x.cab, and then is installed.

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

At this time, there is no removal required for the Trojan itself because it runs from a Web site. The detection indicates that it has been detected on the Web site and stopped. However, if the Trojan was successful in downloading Adware.VirtuMonde, it should be removed.