An SQL Injection issue in the list controller of the Prestahome Blog (aka ph_simpleblog) module before 1.7.8 for Prestashop allows a remote attacker to extract data from the database via the sb_category parameter.

Summary

  • CVE ID: CVE-2021-36748
  • Published at: 2021-08-20
  • Advisory source: sorcery.ie
  • Platform: PrestaShop
  • Product: ph_simpleblog
  • Impacted release: < 1.7.8
  • Product author: Prestahome
  • Weakness: CWE-89
  • Severity: critical (9.8)

Description

This blog post details an SQLi sorcery.ie found in Blog for Prestashop (ph_simpleblog) by Prestahome.

WARNING : This exploit is actively used to deploy webskimmer to massively steal credit cards.

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.

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 the FRONT to exposed tokens and unlock admins’ ajax scripts
  • Rewrite SMTP settings to hijack emails

  • Proof of concept

https://preprod.X/module/simpleblog/list?sb_category=1%27%29%3BSELECT+0x73656c65637420736c656570283130293b+INTO+%40var_name%3Bselect+%40var_name%3Bprepare+stmt+from+%40var_name%3B+execute+stmt;--

Patch for version 1.7.7

--- a/modules/ph_simpleblog/models/SimpleBlogCategory.php
+++ b/modules/ph_simpleblog/models/SimpleBlogCategory.php
@@ -421 +421 @@ class SimpleBlogCategory extends ObjectModel
-            $sql->where('l.link_rewrite = \'' . $rewrite . '\' AND l.id_lang = ' . (int) $id_lang);
+            $sql->where('l.link_rewrite = \'' . pSQL($rewrite) . '\' AND l.id_lang = ' . (int) $id_lang);
@@ -423 +423 @@ class SimpleBlogCategory extends ObjectModel
-            $sql->where('l.link_rewrite = \'' . $rewrite . '\'');
+            $sql->where('l.link_rewrite = \'' . pSQL($rewrite) . '\'');
@@ -436 +436 @@ class SimpleBlogCategory extends ObjectModel
-        $sql->where('l.id_simpleblog_category = ' . $id_simpleblog_category . ' AND l.id_lang = ' . (int) $id_lang);
+        $sql->where('l.id_simpleblog_category = ' . (int) $id_simpleblog_category . ' AND l.id_lang = ' . (int) $id_lang);
@@ -461 +461 @@ class SimpleBlogCategory extends ObjectModel
-        $tmp_location = _PS_TMP_IMG_DIR_ . 'ph_simpleblog_cat_' . $object->id . '.' . $object->cover;
+        $tmp_location = _PS_TMP_IMG_DIR_ . 'ph_simpleblog_cat_' . (int) $object->id . '.' . $object->cover;
@@ -466 +466 @@ class SimpleBlogCategory extends ObjectModel
-        $orig_location = _PS_MODULE_DIR_ . 'ph_simpleblog/covers_cat/' . $object->id . '.' . $object->cover;
+        $orig_location = _PS_MODULE_DIR_ . 'ph_simpleblog/covers_cat/' . (int) $object->id . '.' . $object->cover;

--- a/modules/ph_simpleblog/models/SimpleBlogPost.php
+++ b/modules/ph_simpleblog/models/SimpleBlogPost.php
@@ -291 +291 @@ class SimpleBlogPost extends ObjectModel
-            $sql->where('sbp.id_simpleblog_post ' . $filter . ' (' . implode(',', $selected) . ')');
+            $sql->where('sbp.id_simpleblog_post ' . ($filter == 'IN' ? 'IN' : 'NOT IN') . ' (' . implode(',', array_map('intval', $selected)) . ')');
@@ -413 +413 @@ class SimpleBlogPost extends ObjectModel
-            $sql->where('sbp.id_simpleblog_post ' . $filter . ' (' . implode(',', $selected) . ')');
+            $sql->where('sbp.id_simpleblog_post ' . ($filter == 'IN' ? 'IN' : 'NOT IN') . ' (' . implode(',', array_map('intval', $selected)) . ')');
@@ -504 +504 @@ class SimpleBlogPost extends ObjectModel
-            $sql->where('l.link_rewrite = \'' . $rewrite . '\'');
+            $sql->where('l.link_rewrite = \'' . pSQL($rewrite) . '\'');
@@ -507 +507 @@ class SimpleBlogPost extends ObjectModel
-            $sql->where('l.link_rewrite = \'' . $rewrite . '\'');
+            $sql->where('l.link_rewrite = \'' . pSQL($rewrite) . '\'');
@@ -521 +521 @@ class SimpleBlogPost extends ObjectModel
-            $sql->where('l.link_rewrite = \'' . $rewrite . '\'');
+            $sql->where('l.link_rewrite = \'' . pSQL($rewrite) . '\'');
@@ -538 +538 @@ class SimpleBlogPost extends ObjectModel
-                    $sql->where('l.link_rewrite = \'' . $rewrite . '\' AND l.id_lang = ' . (int) $id_lang);
+                    $sql->where('l.link_rewrite = \'' . pSQL($rewrite) . '\' AND l.id_lang = ' . (int) $id_lang);
@@ -540 +540 @@ class SimpleBlogPost extends ObjectModel
-                    $sql->where('l.link_rewrite = \'' . $rewrite . '\'');
+                    $sql->where('l.link_rewrite = \'' . pSQL($rewrite) . '\'');
@@ -820 +820 @@ class SimpleBlogPost extends ObjectModel
-            $sql = 'UPDATE `' . _DB_PREFIX_ . 'simpleblog_post` SET `likes` = `likes` + 1 WHERE id_simpleblog_post = ' . $id_simpleblog_post;
+            $sql = 'UPDATE `' . _DB_PREFIX_ . 'simpleblog_post` SET `likes` = `likes` + 1 WHERE id_simpleblog_post = ' . (int) $id_simpleblog_post;
@@ -822 +822 @@ class SimpleBlogPost extends ObjectModel
-            $sql = 'UPDATE `' . _DB_PREFIX_ . 'simpleblog_post` SET `likes` = `likes` - 1 WHERE id_simpleblog_post = ' . $id_simpleblog_post;
+            $sql = 'UPDATE `' . _DB_PREFIX_ . 'simpleblog_post` SET `likes` = `likes` - 1 WHERE id_simpleblog_post = ' . (int) $id_simpleblog_post;
@@ -829 +829 @@ class SimpleBlogPost extends ObjectModel
-        $sql = 'SELECT `likes` FROM `' . _DB_PREFIX_ . 'simpleblog_post` WHERE id_simpleblog_post = ' . $id_simpleblog_post;
+        $sql = 'SELECT `likes` FROM `' . _DB_PREFIX_ . 'simpleblog_post` WHERE id_simpleblog_post = ' . (int) $id_simpleblog_post;
@@ -838 +838 @@ class SimpleBlogPost extends ObjectModel
-        $sql = 'UPDATE `' . _DB_PREFIX_ . 'simpleblog_post` SET `views` = `views` + 1 WHERE id_simpleblog_post = ' . $this->id_simpleblog_post;
+        $sql = 'UPDATE `' . _DB_PREFIX_ . 'simpleblog_post` SET `views` = `views` + 1 WHERE id_simpleblog_post = ' . (int) $this->id_simpleblog_post;

--- a/modules/ph_simpleblog/models/SimpleBlogPostType.php
+++ b/modules/ph_simpleblog/models/SimpleBlogPostType.php
@@ -68 +68 @@ class SimpleBlogPostType extends ObjectModel
-        $sql->where('slug = \'' . $slug . '\'');
+        $sql->where('slug = \'' . pSQL($slug) . '\''

Other recommendations

  • Upgrade the module to the most recent version
  • 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_ by a new longer arbitrary prefix. Nevertheless, be warned that this is useless against blackhats with DBA senior skills 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 these set of rules.

Timeline

Date Action
18-06-2021 Issue discovered during a pentest
13-07-2021 Reported issue to Prestahome
14-07-2021 Prestahome patched the issue in version 1.7.8
15-07-2021 Number CVE-2021-36748 assigned
18-08-2021 Blog post released
20-08-2021 pajoda released a Nuclei template for this CVE