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Security

Drupal Fixes Highly Critical SQL Injection Flaw 54

An anonymous reader writes Drupal has patched a critical SQL injection vulnerability in version 7.x of the content management system that can allow arbitrary code execution. The flaw lies in an API that is specifically designed to help prevent against SQL injection attacks. "Drupal 7 includes a database abstraction API to ensure that queries executed against the database are sanitized to prevent SQL injection attacks," the Drupal advisory says. "A vulnerability in this API allows an attacker to send specially crafted requests resulting in arbitrary SQL execution. Depending on the content of the requests this can lead to privilege escalation, arbitrary PHP execution, or other attacks."
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Drupal Fixes Highly Critical SQL Injection Flaw

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  • by Anonymous Coward

    I've seen no mention of whether or not Drupal 6.x is vulnerable; are they?

    • by Hewligan ( 202585 ) on Wednesday October 15, 2014 @06:59PM (#48154983)

      I've seen no mention of whether or not Drupal 6.x is vulnerable; are they?

      No, it won't be affected, as the API involved was introduced in Drupal 7.

      • Considering that the API is to help protect against SQL injection though, it's probably fair to say that version 6 is affected by other issues.

        • Considering that the API is to help protect against SQL injection though, it's probably fair to say that version 6 is affected by other issues.

          Not really. The API makes it easier for developers to avoid SQL injection vulns. That doesn't mean that code not using it has SQL vulns.

      • I've seen no mention of whether or not Drupal 6.x is vulnerable; are they?

        No, it won't be affected, as the API involved was introduced in Drupal 7.

        No, but it's certainly an indicator of the quality of code. Don't be surprised if other vulnerabilities are discovered as everyone shifts their attention and starts scrutinizing the rest of the code. The code diff is below. It's a pretty amateurish mistake, and had someone reviewed or tested the original code, they'd have seen it didn't do what it was supposed to. The comments even give you a big hint what the next vulnerability is going could be.

        diff --git a/includes/database/database.inc b/include

  • Heh (Score:5, Funny)

    by bunratty ( 545641 ) on Wednesday October 15, 2014 @06:44PM (#48154923)

    The flaw lies in an API that is specifically designed to help prevent against SQL injection attacks.

    You had one job!

    • Re: (Score:2, Insightful)

      by Anonymous Coward
      So were they "sanitizing" full-text queries instead of using prepared statements? [wikipedia.org] That's like polishing a turd. No mater how hard you polish, you still have a turd.
      • No, it's more like they were enforcing parametrised queries on top of an API that allows non-parametrised queries.

      • Re:Heh (Score:5, Informative)

        by amicusNYCL ( 1538833 ) on Wednesday October 15, 2014 @07:14PM (#48155095)

        It looks like a feature where you could supply one placeholder in a prepared statement, but give it an array of values, and it would expand the placeholders to fit the array. So if the query was like this:

        SELECT * FROM table WHERE id IN (:idlist)

        and you passed an array with 3 values for idlist, it would replace the query like this:

        SELECT * FROM table WHERE id IN (:idlist_1, :idlist_2, :idlist_3) ... then use the values in the array as the three values for those placeholders. It looks like the old code was using the keys from the data array, so instead of appending someting like "_1", it would append the actual key. So an attacker could put SQL code into the array keys and it would stick those (unchanged) into the query.

        Here is the old code (without comments):

        foreach (array_filter($args, 'is_array') as $key => $data) {
                    $new_keys = array();
                    foreach ($data as $i => $value) {
                        $new_keys[$key . '_' . $i] = $value;
                    }
                    $query = preg_replace('#' . $key . '\b#', implode(', ', array_keys($new_keys)), $query);

        And the new code:

        foreach (array_filter($args, 'is_array') as $key => $data) {
                    $new_keys = array();
                    foreach (array_values($data) as $i => $value) {
                        $new_keys[$key . '_' . $i] = $value;
                    }
                    $query = preg_replace('#' . $key . '\b#', implode(', ', array_keys($new_keys)), $query);

        array_values will return an array with numeric indexes, which is what removes the vulnerability.

        • by Anonymous Coward

          Since the first way is the natural way to write the loop, the flaw lies in PHP. In fact, I think the underlying vulnerability is the fact that PHP doesn't have (and enforce) separate types for arrays and maps.

          • If this were a map, say in Python, then the programmer would have to supply the value $i (or in Python, just i) with an ++$i (or in Python i+=1). This can be done in PHP too, so there is no disadvantage to what PHP supports. The problem here is that the programmer is putting dynamic code in the SQL query without sanitizing it first. So what if it is supposed to be variables that are not supposed to be affected by the user? The first rule of preventing SQL injection is to use ZERO outside string variables, e

    • Kind of like a flu vaccine that give you... the flu

  • by Art3x ( 973401 ) on Wednesday October 15, 2014 @07:38PM (#48155239)

    I understand database abstration layers that let you write:

    db_query('select * from table where id = 3')

    instead of:

    mysql_query('select * from table where id = 3')
    or
    pgsql_query('select * from table where id = 3')

    But I'm not sure I understand why you would want even more abstraction that lets you write:

    db_select('*').from('table').where({ id: 3 })

    ---

    Sealing against SQL injection isn't that hard. Don't ever write:

    select * from table where id = $id

    If you see a dollar sign in an SQL string, it should catch your eye. Instead use parametric queries whenever you can:

    select * from table where id = ? or
    select * from table where id = $1 or
    select * from table where id = :id or
    whatever your programming language's syntax is.

    Maybe variables in queries are unavoidable, if you have some kind of query building code:

    if ($x) {
        $table = 'x';
    } else {
        $table = 'y';
    }

    $q = db_prepare("select * from $table where id = ?");

    Does anyone have a better way to build up queries?

    • Prepared statements, stored procedures.
      • Go google for "php prepared statements in clause" and see how the very first result is a "solution" that is vulerable to SQL injection.

    • This does enable precisely the parametric queries you're talking about.

    • Sealing against SQL injection isn't that hard. Don't ever write:

      select * from table where id = $id

      Does anyone have a better way to build up queries?

      The forbidden example above looks to be the easiest and most readable of all the variants you have provided...

      SQL context aware eval() routines with safe default marshaling assumptions are relatively trivial to write.

      Much better to give people what they want rather than forcing them to use parameterized semantics where not ideal. If web platforms did this from the beginning CVE databases would be much lighter than they have become.

      • SQL context aware eval() routines with safe default marshaling assumptions are relatively trivial to write.

        Could you post a trivial example of one?

    • You might want to take a look how the Banshee PHP framework [banshee-php.org] deals with SQL. With its SQL driver and the security_audit script, it's really hard to have an SQL injection error in your code.
  • Maybe I'm missing something, but aren't injection attacks a non-issue with parameterized stored procs?

    I'm unclear on what their API is doing, but it can't just allowing people to insert anything in a query can it?

  • Quick, patch whitehouse.gov ;-)

    http://radar.oreilly.com/2009/... [oreilly.com]

    http://buytaert.net/whitehouse... [buytaert.net]

    More seriously, I assume they also run some kind of WAF that would catch the attempt even if drupal wasn't yet patched since I do and I am much much smaller.

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