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Given that the exploit relies on using byte sequences that cannot be interpreted as valid utf8 strings, I would think that anyone writing a script that uses the "-T" flag, and expects to handle utf8 data from a tainted source, would prefer to read such input as ":raw", and always use Encode::decode() to convert it to perl-internal utf8 form.

And in doing so, it would usually be prudent to do it like this (adapting the sample code given in the OP):

#!/usr/bin/perl -T use strict; use Encode; %ENV = ( PATH => '/usr/bin' ); open my $filehandle, "< :raw", "test.bin" or die $!; my $word = readline $filehandle; eval { $word = decode( "utf8", $word, Encode::FB_CROAK ) }; if ( $@ ) { warn "unusable input from test.bin\n"; } else { my ($untainted) = $word =~ /^(\w+)$/; if ($untainted) { # It passed the regex, so it is "safe". system "echo $untainted"; } }

In reply to Re: UTF8 related proof of concept exploit released at T-DOSE by graff
in thread UTF8 related proof of concept exploit released at T-DOSE by Juerd

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