42 lines
2.2 KiB
Plaintext
42 lines
2.2 KiB
Plaintext
HACKER PROOF DOORS!
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It is possible.
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There is a basic flaw in doors that RBBS doesn't cover. The RBBS program
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doesn't keep users from uploading ".BAT" files. Consider this:
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RBBS has three basic tests to get into doors.
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1> the user must have high enough access level.
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2> the door requested must be listed on the door menu.
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3> the bat file with the same name must be on the disk.
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If the hacker is on the ball, he/she (let's give women some credit) would
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first upload the bat file. In #2 above RBBS checks the Door menu line at a
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time with an "INSTR" command looking for matches. Hence if the door is called
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"GAME" then G,GA,GAM,AM,AME,M,ME,E,A all are valid and will pass the second
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test. So all a user would have to do is upload a file called "GAM.BAT" then go
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to doors. Rather than entering "GAME", they enter "GAM" and the GAM.BAT door
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is opened. They could format c: or CTTY to com1 and get full access to your
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hard disk.
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So if you want to open the doors you will need to change one line:
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20741 A=1:GOSUB 5000:F$=MID$(FA$,X,1)+":"+Z$:IF INSTR(F$,"?") OR INSTR(F$,"*")
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OR INSTR(F$," ") OR INSTR(F$,".DEF") OR INSTR(F$,".OLD") OR INSTR(F$,".BAT")
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OR INSTR(F$,"\") OR INSTR(3,F$,":") OR MID$(F$,LEN(F$),1)="." THEN A=2:RETURN
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With the above change nobody can up or down load files with those extensions.
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Since they can no longer upload files with the .bat ext. then they can't crash
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in through the cracks.
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The only thing left is the users input. If you use the CTTY command they have
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full access to your system. Try opening your doors in a limited fashion. ie
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Output only. There are a lot of useful programs that can be run in this mode.
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I have my doors open with a Basic compiler program. The user uploads a file to
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compile and enters doors. The doors runs a bat file that runs the basic
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compiler with the output redirected to the com port. The user sees what is
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happening but has no ability to change anything. The program is compiled,
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linked, and arc'ed in front of them and the board returns so they may download
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the compiled arc'ed program.
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If the above two items are implemented, you can operate the doors without
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worrying about hackers.
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