Re: Telnetd AYT overflow scanner

From: der Mouse (mouseat_private)
Date: Wed Jul 25 2001 - 13:18:00 PDT

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    > /*
    >  * Telnetd AYT overflow scanner, by Security Point(R)
    >  *              Bug found by scut of TESO Security
    [...]
    >  * With Security Point(R) Scanner you can find and repair the
    >  * Vulnerabilities before the bad guys get in.
    
    Does anyone else find it as ironic as I that this code contains
    a..buffer overflow?
    
    > char sendbuffer[5120*2];
    
    >     bzero(sendbuffer,sizeof(sendbuffer));
    >     for (i=0;i!=(sizeof(sendbuffer)/2);i++) {
    > 	sprintf(sendbuffer,"%s%c%c",sendbuffer,255,246); // 0xff 0xf6 - IAC AYT
    >     }
    
    Quite aside from the _horrible_ misuse of sprintf, this writes a NUL
    one byte past the end of sendbuffer[].
    
    I sure wouldn't trust anything about my system to code from whoever
    wrote this.  Just on a quick once-over, I see seven other things I
    would say are wrong with it.
    
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