## Documents for known

Code [kis001a]

The indicated file is a directory. The file is a known location used by intruders. This should be considered a sign that this system has been compromised. The system should be checked for other signs of intrusion and cleaned up.

Code [kis002a]

The indicated file is a known location used by intruders. This should be considered a sign that this system has been compromised. The system should be checked for other signs of intrusion and cleaned up.

Code [kis003a]

The indicated window server directory contains files other than UNIX data-gram sockets. This should be considered a sign that this system has been compromised. The system should be checked for other signs of intrusion and cleaned up.

Code [kis004w]

The 'lost+found' directory (one exists for each file system) is used by the `fsck' program as a directory for re-linking "dangling" files during the file system check. These directories should be checked when a file system check is not clean and files recovered from here. This directory is also used by intruders to store files, as it is often ignored. The files found here should be checked. If any unusual files are found, the system should be checked for other signs of intrusion. In any event, the 'lost+found' directories should be kept clean.

Code [kis005a]

The /bin/login program appears to have a back-door installed. The program should be compared against distribution media and replaced if it has been altered. The system should be checked for other signs of intrusion and cleaned.

Code [kis006e]

The attempt to compile the program to check the setuid() system call failed for some reason. This will prevent the test from occurring.

Code [kis007a]

The setuid() system call succeeded even though the user was not root. This most likely indicates that the system has been compromised and the OS altered. A new kernel should be installed and the machine rebooted.

Code [kis008w]

The indicated file in the system mail spool does not have a name which matches the owner. This indicates either an attempt to create a mailbox for another user (allowing someone else to read that persons mail), or that the mail spool is being used to store files. These files should be checked, and if unusual, the system should be examined for other signs of intrusion.

Code [kis009w]

There is an .exrc file outside of any user's home directory. This file can be loaded inadvertenly by a user if executing an editor in that directory and could introduce unexpected commands through it. Note that in all modern versions of vi, you have to set the exrc option in your home's directory .exrc file before vi will read the exrc in the current directory (using 'set exrc'). If you are using an old version of vi or users have this option enabled, however, commands in .exrc might compromise the security of your system.

Code [kis010w]

The indicated file in the system mail spool does not belong to any user in the system. This might indicate that a user has been removed but not his mailbox or that this mailbox has been created wrongly. These files should be checked and, if belonging to former users, removed. (Note: this warning will be given too if, for some reason, the user running Tiger cannot access the user database)

Code [kis011f]

A server in the system (that is, a process with a listening socket towards the Internet) or its parent process has an open file which has been removed from the system. This might be a usual behaviour in the process or it might be an indication of an intruder that has executed a backdoor in the system (which opens a connection to accept requests from the Internet) and has later removed the program from the system so that it cannot be traced back to him. This also can happen if a local service is using shared libraries which have been upgraded but the service itself has not been restarted in order to use the new libraries. Notice that if there was a vulnerability in the library and the server is not restarted the system is still vulnerable.

Code [kis012w]

An application in the system is using a deleted file. This might be an indication of an intruder executing rogue processes and removing the files from disk so that they cannot be traced or detected by the local administrator. This has been observerd both in intruders running password cracking programs or worms propagating through remote attacks. This also can happen if a local application is using shared libraries which have been upgraded but the service itself has not been restarted in order to use the new libraries.