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BREAKING CHANGE: Verify the SAMLResponse based on the raw query string #85

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Merged
merged 1 commit into from
Aug 19, 2022
Merged

BREAKING CHANGE: Verify the SAMLResponse based on the raw query string #85

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2 changes: 2 additions & 0 deletions Makefile.PL
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Original file line number Diff line number Diff line change
Expand Up @@ -45,6 +45,7 @@ my %WriteMakefileArgs = (
"Types::Serialiser" => 0,
"URI" => 0,
"URI::Encode" => 0,
"URI::Escape" => 0,
"URI::QueryParam" => 0,
"URN::OASIS::SAML2" => "0.002",
"XML::Enc" => "0.05",
Expand Down Expand Up @@ -124,6 +125,7 @@ my %FallbackPrereqs = (
"Types::Serialiser" => 0,
"URI" => 0,
"URI::Encode" => 0,
"URI::Escape" => 0,
"URI::QueryParam" => 0,
"URI::URL" => 0,
"URN::OASIS::SAML2" => "0.002",
Expand Down
1 change: 1 addition & 0 deletions cpanfile
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Expand Up @@ -29,6 +29,7 @@ requires "MooseX::Types::URI" => "0";
requires "Types::Serialiser" => "0";
requires "URI" => "0";
requires "URI::Encode" => "0";
requires "URI::Escape" => "0";
requires "URI::QueryParam" => "0";
requires "URN::OASIS::SAML2" => "0.002";
requires "XML::Enc" => "0.05";
Expand Down
107 changes: 39 additions & 68 deletions lib/Net/SAML2/Binding/Redirect.pm
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Original file line number Diff line number Diff line change
@@ -1,19 +1,24 @@
use strict;
use warnings;
package Net::SAML2::Binding::Redirect;
use Moose;

# VERSION

use Moose;
use Carp qw(croak);
use Crypt::OpenSSL::RSA;
use Crypt::OpenSSL::X509;
use File::Slurper qw/ read_text /;
use IO::Compress::RawDeflate qw/ rawdeflate /;
use IO::Uncompress::RawInflate qw/ rawinflate /;
use MIME::Base64 qw/ encode_base64 decode_base64 /;
use MooseX::Types::URI qw/ Uri /;
use Net::SAML2::Types qw(signingAlgorithm SAMLRequestType);
use Carp qw(croak);
use URI::Encode qw/uri_decode/;
use URI::Escape qw(uri_unescape);
use URI::QueryParam;
use URI;

# ABSTRACT: Net::SAML2::Binding::Redirect - HTTP Redirect binding for SAML

=head1 NAME

Net::SAML2::Binding::Redirect

=head1 SYNOPSIS

my $redirect = Net::SAML2::Binding::Redirect->new(
Expand All @@ -32,16 +37,6 @@ Net::SAML2::Binding::Redirect

=cut

use MIME::Base64 qw/ encode_base64 decode_base64 /;
use IO::Compress::RawDeflate qw/ rawdeflate /;
use IO::Uncompress::RawInflate qw/ rawinflate /;
use URI;
use URI::QueryParam;
use Crypt::OpenSSL::RSA;
use Crypt::OpenSSL::X509;
use File::Slurper qw/ read_text /;
use URI::Encode qw/uri_decode/;

=head2 new( ... )

Constructor. Creates an instance of the Redirect binding.
Expand Down Expand Up @@ -218,7 +213,7 @@ sub sign {
return $u->as_string;
}

sub _verified {
sub _verify {
my ($self, $sigalg, $signed, $sig) = @_;

foreach my $crt (@{$self->cert}) {
Expand All @@ -235,84 +230,60 @@ sub _verified {
$rsa_pub->use_sha512_hash;
} elsif ($sigalg eq 'http://www.w3.org/2000/09/xmldsig#rsa-sha1') {
$rsa_pub->use_sha1_hash;
} else {
warn "Unsupported Signature Algorithim: $sigalg" if ($self->debug);
}

if ($rsa_pub->verify($signed, $sig)) {
return 1;
else {
warn "Unsupported Signature Algorithim: $sigalg, defaulting to sha256" if $self->debug;
}

warn "Unable to verify with " . $cert->subject if ($self->debug);
return 1 if $rsa_pub->verify($signed, $sig);

warn "Unable to verify with " . $cert->subject if $self->debug;
}

die "bad sig";
croak("Unable to verify the XML signature");
}

=head2 verify( $url )
=head2 verify( $query_string )

Decode a Redirect binding URL.

Verifies the signature on the response.

Requires the *raw* query string to be passed, because L<URI> parses and
re-encodes URI-escapes in uppercase (C<%3f> becomes C<%3F>, for instance),
which leads to signature verification failures if the other party uses lower
case (or mixed case).

=cut

sub verify {
my ($self, $url) = @_;
my $u = URI->new($url);

# verify the response
my $sigalg = $u->query_param('SigAlg');
# This now becomes the query string
$url =~ s#^https?://.+\?##;

my $signed;
my $saml_request;
my $sig = $u->query_param_delete('Signature');
my %params = map { split(/=/, $_, 2) } split(/&/, $url);

# During the verify the only query parameters that should be in the query are
# 'SAMLRequest', 'RelayState', 'Sig', 'SigAlg' the other parameter values are
# deleted from the URI query that was created from the URL that was passed
# to the verify function
my @signed_params = ('SAMLRequest', 'SAMLResponse', 'RelayState', 'Sig', 'SigAlg');

for my $key ($u->query_param) {
if (grep /$key/, @signed_params ) {
next;
}
$u->query_param_delete($key);
}
my $sigalg = uri_unescape($params{SigAlg});

# Some IdPs (PingIdentity) seem to double encode the LogoutResponse URL
if ($self->sls_double_encoded_response) {
#if ($sigalg =~ m/%/) {
$signed = uri_decode($u->query);
$sig = uri_decode($sig);
$sigalg = uri_decode($sigalg);
$saml_request = uri_decode($u->query_param($self->param));
} else {
$signed = $u->query;
$saml_request = $u->query_param($self->param);
}
my $encoded_sig = uri_unescape($params{Signature});
my $sig = decode_base64($encoded_sig);

# What can we say about this one Microsoft Azure uses lower case in the
# URL encoding %2f not %2F. As it is signed as %2f the resulting signed
# needs to change it to lowercase if the application layer reencoded the URL.
if ($self->sls_force_lcase_url_encoding) {
# TODO: This is a hack.
$signed =~ s/(%..)/lc($1)/ge;
my @signed_parts;
for my $p ($self->param, qw(RelayState SigAlg)) {
push @signed_parts, join('=', $p, $params{$p}) if exists $params{$p};
}
my $signed = join('&', @signed_parts);

$sig = decode_base64($sig);

$self->_verified($sigalg, $signed, $sig);
$self->_verify($sigalg, $signed, $sig);

# unpack the SAML request
my $deflated = decode_base64($saml_request);
my $deflated = decode_base64(uri_unescape($params{$self->param}));
my $request = '';
rawinflate \$deflated => \$request;

# unpack the relaystate
my $relaystate = $u->query_param('RelayState');

my $relaystate = uri_unescape($params{'RelayState'});
return ($request, $relaystate);
}

Expand Down
9 changes: 3 additions & 6 deletions t/17-lowercase-url-escaping.t
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Original file line number Diff line number Diff line change
@@ -1,6 +1,5 @@
use Test::Lib;
use Test::Net::SAML2;
use Test::More tests => 2;

use Net::SAML2::Binding::Redirect;
use File::Slurper qw/read_text/;
Expand All @@ -15,13 +14,11 @@ my $redirect = Net::SAML2::Binding::Redirect->new(
param => 'SAMLRequest',
cert => read_text('t/net-saml2-cert.pem'),
sig_hash => 'sha256',
sls_force_lcase_url_encoding => 1,
);

my ($request, $relaystate) = $redirect->verify($url);

like($request, qr/NETSAML/, 'Good Signature if sls_force_lcase_url_encoding = 1');
like($request, qr/NETSAML/,
"Good Signature because we now don't alter the input with URI anymore");

$redirect->{sls_force_lcase_url_encoding} = 0;

throws_ok( sub { $redirect->verify($url) }, qr/bad sig/, "Bad Signature if sls_force_lcase_url_encoding = 0");
done_testing();