S.u.S.E. in.identd Denial of Service Vulnerability

The in.identd service is used to provide remote systems with usernames associated with tcp connection port pairs. The version of in.identd that ships with S.u.S.E. Linux contains a remotely exploitable denial of service vulnerability that may result in the service crashing.

Though the denial of service is the result of oversized input recieved by the server, it is not an overflow. What happens is that the identd server realizes that the input is too long and changes the value of some pointer to NULL. The server then attempts to dereference this pointer and terminates due to a segmentation violation.

The S.u.S.E. ident daemon is multithreaded and is not spawned via inetd. There is only one in.identd process started, usually by init. As a result, if it is terminated it is not restarted. A denial of the identd service occurs until manually restarted.


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