Re: FreeBSD Security Advisory FreeBSD-SA-02:23.stdio

From: Steven M. Bellovin (smbat_private)
Date: Mon Apr 22 2002 - 15:30:25 PDT

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    It's amazing that this has taken so long to resurface.  This is an 
    ancient bug -- see, for example, Henry Spencer's suid man page from 
    1987 (http://groups.google.com/groups?q=checklist+security+setuid+-linux+group:alt.security&hl=en&scoring=r&selm=1991May14.101450.830%40convex.com&rnum=1
    quotes it).  The document notes, among other pieces of sage advice, the 
    following:
    
    	One or more of the standard descriptors might be closed, so that
    	an opened file might get (say) descriptor 1, causing chaos if the
    	program tries to do a
    	.IR printf .
    
    I seem to recall the same suggestion in an early document by Jim Ellis 
    and (I think) Tom Truscott, but I can't find a copy at the moment.
    
    
    		--Steve Bellovin, http://www.research.att.com/~smb
    		Full text of "Firewalls" book now at http://www.wilyhacker.com
    



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