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";
}
}
-
Are you posting in the right place? Check out Where do I post X? to know for sure.
-
Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
<code> <a> <b> <big>
<blockquote> <br /> <dd>
<dl> <dt> <em> <font>
<h1> <h2> <h3> <h4>
<h5> <h6> <hr /> <i>
<li> <nbsp> <ol> <p>
<small> <strike> <strong>
<sub> <sup> <table>
<td> <th> <tr> <tt>
<u> <ul>
-
Snippets of code should be wrapped in
<code> tags not
<pre> tags. In fact, <pre>
tags should generally be avoided. If they must
be used, extreme care should be
taken to ensure that their contents do not
have long lines (<70 chars), in order to prevent
horizontal scrolling (and possible janitor
intervention).
-
Want more info? How to link
or How to display code and escape characters
are good places to start.
|