Summary
Kork is a worm that uses the known vulnerability in lpd service to propagate from a vulnerable Linux system to another. This service is part of the default installation of Red Hat Linux 7.0.
Removal
Based on the settings of your F-Secure security product, it will either move the file to the quarantine where it cannot spread or cause harm, or remove it.
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
Variant:Kork.A
If the worm finds a vulnerable host, it first creates two users, "kork" and "kork2", to the system without a password. "kork2" user has a root priviledge.
Kork also adds an open shell to port 666.
Next it attempts to download a trojanized login and the main part of the trojan from a web site. Since April 26th, 2001, neither of these files are available, so the worm cannot replicate any further. However, already infected machines are able to compromise other vulnerable machines by adding an open shell and users to the system.
If the download is completed, the worm installs trojanized "/bin/login" and "/bin/ps" to the system. It attemps to send sensitive system data propably to the virus writer.
Original "/bin/ps" is copied to "/usr/bin/.ps" and the original "/bin/login" is copied to "/bin/.login".
Finally the worm starts to scan random Class-B subnets for vulnerable hosts.
The vulnerability in the lpd daemon is known and already fixed within updated provided by Red Hat at: https://www.redhat.com/support/errata/rh7-errata-security.html
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