Re: KSR[T] Advisory #7: filter

From: hurtta+zzat_private
Date: Mon Feb 23 1998 - 23:14:08 PST

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    KSR[T]:
    > Affected Program:    filter ( part of the elm-2.4 package )
    <...>
    > Notes:               This was not a full audit on the elm2.4 package, or
    >                      filter for that matter.  At a glance, there appear
    >                      to be numerous security problems.
    >
    >                      The filter included in elm-2.4ME+37 also appears to
    >                      be vulnerable to the "save_embedded_address()" attack,
    >                      but not to the "get_filter_rules()" attack.
    >
    >                      Filter will not be a part of elm 2.5, and is
    >                      not supported in any way at this time.  It is the
    >                      Elm group's recommendation that filter not be used.
    >
    > Patch/Fix:
    >
    > -*- Begin elm 2.4 filter patch -*-
    >
    > diff -u filter/filter.c filter.new/filter.c
    > --- filter/filter.c     Tue Feb  4 09:13:02 1997
    > +++ filter.new/filter.c Tue Feb  4 09:17:38 1997
    > @@ -429,7 +429,7 @@
    >         **/
    >
    >         static int processed_a_reply_to = 0;
    > -       char address[LONG_STRING];
    > +       char address[MAX_LINE_LEN + 1];
    >         register int i, j = 0;
    
    Enlarging of address does causes just that then there is overflow in
    
            strcpy(from,address);
    
    (
    char to[VERY_LONG_STRING],
         from[LONG_STRING],
         subject[LONG_STRING],              /* from current message     */
         sender[LONG_STRING];               /* from current message     */
    )
    
    Better fix loop in save_embedded_address (*).
    (This overflow is not necessary exploitable.)
    
    (in ME+ that strcpy is strfcpy(from,address,sizeof from) and therefore
     bound checked.)
    
    / Kari Hurtta
    
    (*) Look ME+ PL39 patch (http://www.ozone.FMI.FI/KEH/elm-2.4ME+PL39.patch.gz,
        ftp://ftp.ozone.FMI.FI/KEH/elm-2.4ME+PL39.patch.gz)
    



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