From 2c93f0a98f0f6380fd07ea17fd16afa2c6e4925b Mon Sep 17 00:00:00 2001
From: canyonknight <canyonknight@gmail.com>
Date: Sat, 23 Jun 2012 14:40:11 -0400
Subject: Implement token system to fix CSRF vulnerabilities

Specially crafted pages can force authenticated users to unknowingly perform
actions on the AUR website despite being on an attacker's website. This
cross-site request forgery (CSRF) vulnerability applies to all POST data on
the AUR.

Implement a token system using a double submit cookie. Have a hidden form
value on every page containing POST forms. Use the newly added check_token() to
verify the token sent via POST matches the "AURSID" cookie value. Random
nature of the token limits potential for CSRF.

Signed-off-by: canyonknight <canyonknight@gmail.com>
Signed-off-by: Lukas Fleischer <archlinux@cryptocrack.de>
---
 web/lib/acctfuncs.inc.php |  1 +
 web/lib/aur.inc.php       | 10 ++++++++++
 2 files changed, 11 insertions(+)

(limited to 'web/lib')

diff --git a/web/lib/acctfuncs.inc.php b/web/lib/acctfuncs.inc.php
index 9bd6e51..51078b8 100644
--- a/web/lib/acctfuncs.inc.php
+++ b/web/lib/acctfuncs.inc.php
@@ -33,6 +33,7 @@ function display_account_form($UTYPE,$A,$U="",$T="",$S="",
 	print "<input type='hidden' name='Action' value='".$A."' />\n";
 	if ($UID) {
 		print "<input type='hidden' name='ID' value='".$UID."' />\n";
+		print "<input type='hidden' name='token' value='".htmlspecialchars($_COOKIE['AURSID'])."' />\n";
 	}
 	print "</fieldset>";
 	print "<table border='0' cellpadding='0' cellspacing='0' width='80%' style=\"margin:0 auto;\">\n";
diff --git a/web/lib/aur.inc.php b/web/lib/aur.inc.php
index 6bc36ac..8b9f31e 100644
--- a/web/lib/aur.inc.php
+++ b/web/lib/aur.inc.php
@@ -77,6 +77,16 @@ function check_sid($dbh=NULL) {
 	return;
 }
 
+# Verify the supplied token matches the expected token for POST forms
+#
+function check_token() {
+	if (isset($_POST['token'])) {
+		return ($_POST['token'] == $_COOKIE['AURSID']);
+	} else {
+		return false;
+	}
+}
+
 # verify that an email address looks like it is legitimate
 #
 function valid_email($addy) {
-- 
cgit v1.2.3-70-g09d2