Relevanssi 3.5.12 / 3.6.0 SQL Injection

`Details  
================  
Software: Relevanssi  
Version: 3.5.12,3.6.0  
Homepage: https://wordpress.org/plugins/relevanssi/  
Advisory report: https://advisories.dxw.com/advisories/sqli-relevanssi/  
CVE: Awaiting assignment  
CVSS: 8.5 (High; AV:N/AC:L/Au:S/C:C/I:C/A:N)  
  
Description  
================  
SQLi in Relevanssi might allow an admin to read contents of database  
  
Vulnerability  
================  
If logged in as an administrator on any site, you can go to Settings > Relevanssi Premium and potentially extract all values in the database including password hashes and user activation tokens.  
This is achieved by a SQL injection based on the fact that some of the configuration options are appended into a SQL query in a unsafe way.  
The configuration page contains the following code, that allows the user to set the option relevanssi_post_type_weights to any value:  
function update_relevanssi_options() {  
....  
foreach ($_REQUEST as $key => $value) {  
if (substr($key, 0, strlen(\'relevanssi_weight_\')) == \'relevanssi_weight_\') {  
$type = substr($key, strlen(\'relevanssi_weight_\'));  
$post_type_weights[$type] = $value;  
}  
....  
}  
if (count($post_type_weights) > 0) {  
update_option(\'relevanssi_post_type_weights\', $post_type_weights);  
}  
....  
}  
Now when a search is made, the function relevanssi_search is called, this appends the user controled value into the SQL query:  
$post_type_weights = get_option(\'relevanssi_post_type_weights\');  
  
...  
  
!empty($post_type_weights[\'post_tag\']) ? $tag = $post_type_weights[\'post_tag\'] : $tag = $relevanssi_variables[\'post_type_weight_defaults\'][\'post_tag\'];  
  
!empty($post_type_weights[\'category\']) ? $cat = $post_type_weights[\'category\'] : $cat = $relevanssi_variables[\'post_type_weight_defaults\'][\'category\'];  
  
$query = \"SELECT relevanssi.*, relevanssi.title * $title_boost +  
relevanssi.content + relevanssi.comment * $comment_boost +  
relevanssi.tag * $tag + relevanssi.link * $link_boost +  
relevanssi.author + relevanssi.category * $cat + relevanssi.excerpt +  
relevanssi.taxonomy + relevanssi.customfield + relevanssi.mysqlcolumn AS tf  
FROM $relevanssi_table AS relevanssi $query_join  
WHERE $term_cond $query_restrictions\";  
  
Proof of concept  
================  
  
Visit /wp-admin/options-general.php?page=relevanssi%2Frelevanssi.php  
Assign 0.75\' (the default value plus a single quote at the end) to aTag weighta  
Press aSave the optionsa  
Visit /?s=test  
The logs should contain the following error because of the syntax error we introduced: aWordPress database error You have an error in your SQL syntaxa  
  
Note: while itas possible to inject syntax errors, itas currently unknown whether this bug can be used to inject anything that would be useful to an attacker.  
  
Mitigations  
================  
Upgrade to version 3.6.1 or later.  
  
Disclosure policy  
================  
dxw believes in responsible disclosure. Your attention is drawn to our disclosure policy: https://security.dxw.com/disclosure/  
  
Please contact us on [email protected] to acknowledge this report if you received it via a third party (for example, [email protected]) as they generally cannot communicate with us on your behalf.  
  
This vulnerability will be published if we do not receive a response to this report with 14 days.  
  
Timeline  
================  
  
2017-10-02: Discovered  
2017-10-02: Reported to vendor via email  
2017-10-03: First response from vendor  
2017-10-03: Version 3.6.1 released which contains a fix for this bug  
  
  
  
Discovered by dxw:  
================  
Glyn Wintle  
Please visit security.dxw.com for more information.  
  
  
  
  
`