In the module “BLOG - Drive High Traffic & Boost SEO” (ybc_blog) in version up to 3.3.8 from PrestaHero (ETS Soft) for PrestaShop, a guest can perform SQL injection in affected versions.

Summary

  • CVE ID: CVE-2023-43979
  • Published at: 2023-11-14
  • Advisory source: Friends-Of-Presta.org
  • Platform: PrestaShop
  • Product: ybc_blog
  • Impacted release: <= 3.3.8 (4.4.0 fixed the vulnerability)
  • Product author: PrestaHero (ETS Soft)
  • Weakness: CWE-89
  • Severity: critical (9.8)

Description

The method Ybc_blogBlogModuleFrontController::getPosts() has sensitive SQL calls that can be executed with a trivial http call and exploited to forge a SQL injection.

This exploit uses a PrestaShop front controller and most attackers can conceal the module controller’s path during the exploit, so you will never know within your conventional frontend logs that it exploits this vulnerability. You will only see “POST /” inside your conventional frontend logs. Activating the AuditEngine of mod_security (or similar) is the only way to get data to confirm this exploit.

Reminder : Core method Validate::isCleanHtml() is useless against CWE-89, it only targets CWE-79

CVSS base metrics

  • Attack vector: network
  • Attack complexity: low
  • Privilege required: none
  • User interaction: none
  • Scope: unchanged
  • Confidentiality: high
  • Integrity: high
  • Availability: high

Vector string: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Possible malicious usage

  • Obtain admin access
  • Remove data from the associated PrestaShop
  • Copy/paste data from sensitive tables to FRONT to expose tokens and unlock admins’s ajax scripts
  • Rewrite SMTP settings to hijack emails

Patch from 3.3.8

--- 3.3.8/modules/ybc_blog/controllers/front/blog.php
+++ 4.4.0/modules/ybc_blog/controllers/front/blog.php
...
        } elseif (($tag = trim(Tools::getValue('tag'))) != '' && Validate::isCleanHtml($tag)) {
            if ($this->module->friendly && Tools::strpos($_SERVER['REQUEST_URI'], 'tag') !== false && Tools::strpos($_SERVER['REQUEST_URI'], 'ybc_blog') !== false)
                $this->module->redirect($this->module->getLink('blog', array('tag' => $tag)));
            $md5tag = md5(urldecode(trim(Tools::strtolower($tag))));
-           $filter .= " AND p.id_post IN (SELECT id_post FROM `" . _DB_PREFIX_ . "ybc_blog_tag` WHERE tag = '$tag' AND id_lang = " . $this->context->language->id . ")";
+           $filter .= " AND p.id_post IN (SELECT id_post FROM `" . _DB_PREFIX_ . "ybc_blog_tag` WHERE tag = '" . pSQL($tag) . "' AND id_lang = " . $this->context->language->id . ")";

Other recommendations

  • It’s recommended to upgrade to the latest version of the module ybc_blog.
  • Upgrade PrestaShop to the latest version to disable multiquery executions (separated by “;”) - be warned that this functionality WILL NOT protect your SHOP against injection SQL which uses the UNION clause to steal data.
  • Change the default database prefix ps_ with a new longer, arbitrary prefix. Nevertheless, be warned that this is useless against blackhats with DBA senior skill because of a design vulnerability in DBMS
  • Activate OWASP 942’s rules on your WAF (Web application firewall), be warned that you will probably break your backoffice and you will need to pre-configure some bypasses against this set of rules.

Timeline

Date Action
2023-05-21 Issue discovered during a code review by TouchWeb.fr
2023-05-21 Contact PrestaShop Addons security Team to confirm version scope by author
2023-05-22 PrestaShop Addons security Team confirm version scope
2023-09-21 Request a CVE ID
2023-09-27 Received CVE ID
2023-11-14 Publish this security advisory