Threat Descriptions

Cardown

Classification

Category :

Malware

Type :

Trojan

Platform :

Java

Aliases :

Cardown, Java/Cardown.A, TrojanDownloader.Java.DummyMod

Summary

Cardown.A is a Java applet based trojan that downloads and installs Startpage.Y trojan on the system.

Cardown activates when user views a web page or HTML email that contains reference to the trojan file.

Cardown does not replicate and does not infect the host system, the only operations it does is to download and install Startpage.Y trojan component.

Removal

To remove Cardown.A from your system:

  • Apply the fix to the Java VM vulnerability
  • Clear temporary Internet files cache
  • Scan your system to locate the Startpage.Y trojan

A False Positive is when a file is incorrectly detected as harmful, usually because its code or behavior resembles known harmful programs. A False Positive will usually be fixed in a subsequent database update without any action needed on your part. If you wish, you may also:

  • Check for the latest database updates

    First check if your F-Secure security program is using the latest updates, then try scanning the file again.

  • Submit a sample

    After checking, if you still believe the file is incorrectly detected, you can submit a sample of it for re-analysis.

    Note: If the file was moved to quarantine, you need to collect the file from quarantine before you can submit it.

  • Exclude a file from further scanning

    If you are certain that the file is safe and want to continue using it, you can exclude it from further scanning by the F-Secure security product.

    Note: You need administrative rights to change the settings.

Technical Details

Cardown is a Java applet that is heavily obfuscated and uses scrambling in it's strings. The trojan is not packaged in to a Jar file so each component class file is individually loaded when trojan executes, so in most cases the user will get a warning about the first component file and will not receive the rest of the malware.

When the trojan is executed it uses Microsoft Internet Explorer VerifierBug vulnerability to get full privileges by escaping the Java security, and execute its code. Then the trojan downloads bootconf.exe into Windows directory (default C:\Windows) and modifies registry so that the trojan starts automatically at Windows startup.

Further information about the vulnerability in the Microsoft Java VM, including a fix, is available at: https://www.microsoft.com/technet/security/bulletin/ms03-011.asp

The trojan makes following registry changes:

Added registry keys:

  • Software\Microsoft\Windows\CurrentVersion\Run\Internat Conf

Removed registry keys:

  • Software\Microsoft\Windows\CurrentVersion\Explorer\ReconfLast
  • Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced\StartConfCnt