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Re: apcupsd 3.7.2 Denial of Service


From: nash <nash () ROHAN SDSU EDU>
Date: Tue, 12 Dec 2000 09:55:00 -0800


Title:    apcupsd 3.7.2 Denial of Service

Affected Application:    apcupsd daemon
...
Problem:

During startup apcupsd creates a PID-file named "apcupsd.pid" in /var/run
(system specific, maybe other directory) with the ID of the daemon process,
this PID-file is used by the shutdown-script to kill the daemon process.

Unfortunatly this PID-file ist world-writeable (Mode 666, -rw-rw-rw). A
malicious user can overwrite the file with arbitrary process ID's, these
processes will be killed instead of the apcupsd process during restart or
stop of the apcupsd daemon and during system shutdown or restart, the whole
system can be crashed this way.
...
User's who don't want to upgrade can add two lines to the "start" section in
the apcupsd startup script in /etc/rc.d or /sbin/init.d :

why not just add umask 022?


---begin---

    start)
        umask 022
        rm -f /etc/apcupsd/powerfail
        rm -f /etc/nologin
        echo -n "Starting apcupsd power management"
        $APCUPSD || return=$rc_failed
        echo -e "$return"
    ;;

---end---

-Ron

matze () joonix de



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