Tips for Fixing a Hacked WordPress Site - WordCamp Sydney 2016

278 views

Published on

Presentation slides from Vladimir Lasky's talk "Tips for Fixing a Hacked WordPress Site", presented on Sunday 25th September at WordCamp Sydney 2016.

Published in: Software
0 Comments
2 Likes
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total views
278
On SlideShare
0
From Embeds
0
Number of Embeds
46
Actions
Shares
0
Downloads
2
Comments
0
Likes
2
Embeds 0
No embeds

No notes for slide

Tips for Fixing a Hacked WordPress Site - WordCamp Sydney 2016

  1. 1. 1 Tips For Fixing a Hacked WordPress Site Vladimir Lasky http://wpexpert.com.au/ WordCamp Sydney 2016
  2. 2. 2 Bring Back Memories?
  3. 3. 3 Wordfence’s 2016 Survey on How Sites Were Compromised
  4. 4. 4 7-Step Recovery Strategy 1. Assess The Damage 2. Identify Sources of Replacement Data 3. Remove Infected Data and Restore from Replacement Sources 4. Disinfect What Cannot Be Replaced 5. Reconstruct What Cannot Be Disinfected 6. Harden the Security of the Website 7. Repair Damage to Reputation
  5. 5. 5 Common Hurdles that Delay Repairs  Obtaining SSH/FTP Access to Client’s Hosting Server – Especially when client is not owner/administrator of their hosting service  Obtaining Original Installation packages for Premium Themes and Plugins – Especially when site was built by someone else – Often cheaper & faster to re-purchase plugins or themes. Usually ensures renewed support & upgrades
  6. 6. 6 The Goal  Ensuring complete disinfection – There can be no remaining malicious scripts or exploits that can be used to easily compromise the site again
  7. 7. 7 1 - Assessing The Damage
  8. 8. 8 Identifying The Infection  Sucuri Site Check – https://sitecheck.sucuri.net/  Google Webmaster Tools – https://www.google.com/webmasters  If WordPress admin is still accessible, vulnerability scanning plugins like Wordfence – https://wordpress.org/plugins/wordfence/
  9. 9. 9 Sucuri Site Check Example
  10. 10. 10 Wordfence Scan Functionality
  11. 11. 11 Wordfence Scan Settings
  12. 12. 12 2 - Identifying Sources of Replacement Data
  13. 13. 13 Recovering Website Content & Stylesheets  Past Website Backups (Files and Database)  Cached Version of the Website in Google Search – E.g. to see the most recently cached version of website.com, visit google.com and perform the following query: • site:websitehostname.com  Archive.org (also called Internet Archive or Wayback Machine)
  14. 14. 14 Example - Accessing Google’s Cache
  15. 15. 15 Example - Wayback Machine
  16. 16. 16 Recovering WordPress Itself  The latest version of WordPress can always be downloaded from this URL: – https://wordpress.org/latest.tar.gz  Previous versions can be found here: – https://wordpress.org/download/release-archive/
  17. 17. 17 Recovering Website Themes & Plugins  Common Download Locations for Free Plugins: – WordPress.org Theme and Plugin Repositories – GitHub – Theme/Plugin Author’s home page  Premium Themes/Plugins – Ask clients to search their emails for • original theme/plugin installation packages • login details for theme/plugin marketplaces i.e. Envato – Sometimes original theme/plugin packages have been left on the server by a previous developer
  18. 18. 18 Disinfection
  19. 19. 19 What is Secure Shell (SSH)?  Allows you to access a UNIX (Linux) shell on your hosting server - similar to the Command Prompt under Windows  SSH access must be enabled by your web host  Some hosts enable by default, others require a special request, a minority forbid it   Recommended Windows SSH Client is PuTTY – http://www.chiark.greenend.org.uk/~sgtatham/putty/
  20. 20. 20
  21. 21. 21 Why use SSH?  Saves time spent in uploading/downloading files to/from the web host  Lets you run many useful UNIX/Linux shell commands to help quickly locate and repair damage  Avoids triggering infected PHP code within your WordPress installation
  22. 22. 22 Common Infectious Payloads:  Shell code (a back door for the hacker) – Often appears as strangely-named PHP files with obfuscated content  JavaScript code to run in the visitor’s browser that: – retrieves content from external sites (often spam or spam links) – attempts to trigger vulnerabilities in the visitor’s web browser  The attacker boasting about their achievement
  23. 23. 23 Precautions When Making Changes  Backup the site files and database before making any changes – cp –pa public_html prev OR – tar zpcvf prev.tar.gz public_html  Also make backups during each step of disinfection process just in case you make a mistake and have to revert
  24. 24. 24 WordPress Files That Are Often Infected:  Root Folder – wp-config.php – wp-load.php  Anywhere within the installation: – .htaccess – index.php – index.html  Within directory /wp-content/ – Theme templates – Plugin Files
  25. 25. 25 Disinfecting with Wordfence  Wordfence has the ability to compare and replace WordPress core files, theme files and plugin files with official repository versions  Powerful, but still often misses things  Cannot help with custom/premium themes and plugins  Should always be followed up with manual disinfection procedures
  26. 26. 26 Replace WordPress Core Files  Move WordPress core files/folders within the website’s root folder to a quarantined location – Folder wp-includes – Folder wp-admin – Files matching wp-*.php (except wp-config.php), index.php, xmlrpc.php  Download the latest WordPress into a temporary folder and move the new copies of the core files/folders into the website’s root folder
  27. 27. 27 Inspect Site Content Folders  Any remaining issues are likely to be contained within the folder /wp- content  Be suspicious of: – .php files with unusual names – ANY .php files within wp-content/uploads (should not normally be there)  Index.php outside of the root folder files should normally only have something like: – <?php // Silence is golden. ?> – Their purpose is to prevent users from being able to list the directory contents
  28. 28. 28 Finding Files Modified Between Two Dates  Between two dates: – find . -type f -newermt 2010-10-07 ! -newermt 2014-10-08  Between two dates & times: – find . -type f -newermt "2014-10-08 10:17:00" ! -newermt "2014-10-08 10:53:00"  This command will find and move the files to “destdir”: – find srcdir -type f -newermt 2014-08-31 ! -newermt 2014-09- 30 -exec mv -i {} destdir/ ;
  29. 29. 29 Comparing Site Files With A Good Version  The utility diff compares two files/directories and displays lines of text that differ between them.  Comparing with a good version from a backup or installation package may reveal the infection, allowing it to be manually removed with a text editor – E.g. comparing the theme folder with one from a backup • diff –qr mybackup/wp-content/themes/mytheme public_html/wp- content/themes/mytheme – E.g. Comparing an installed plugin with a downloaded package • diff –qr downloads/myplugin public_html/wp-content/myplugin
  30. 30. 30 Searching Contents of Files for Infections  To search within a directory for files containing a search string (regular expression): – fgrep –R foldername “searchstring”  These PHP functions are often present in obfuscated code, so searching for them by name can identify its presence: – base64_decode – gzinflate – eval
  31. 31. 31 Infected Widgets  On occasion, some attacks may result in malicious JavaScript code is inserted into text widgets  Look through your widgets for anything that should not be there
  32. 32. 32 Disinfecting .htaccess  .htaccess contains settings that override the default behaviour of the Apache web server  Malware often overrides the web server’s error handler with its own actions  Detailed topic, but you can delete the .htaccess file in the root folder and recreate it by going to Settings- >Permalinks and selecting “Save Permalinks”  If you are using a page caching plugin that modifies .htaccess, you may need to reconfigure or save its settings again.
  33. 33. 33 Example of Obfuscated PHP Code
  34. 34. 34 Failsafe Disinfection (Last Resort)  Record the installed plugins & themes by: – Accessing WordPress admin or – By inspecting contents of /wp-content/plugins and /wp- content/themes  Use the WordPress Exporter plugin to export page, post and menu content into an export file – https://en-au.wordpress.org/plugins/wp-exporter/  Quarantine the entire WordPress root folder  Setup WordPress from scratch, install the required plugins and themes, import content from the previous export file – https://codex.wordpress.org/Importing_Content
  35. 35. 35 Common Disinfection Hurdles  A theme/plugin with a security vulnerability is no longer maintained – Hire a developer to audit the code and fix its security weaknesses – Replace with a newer theme/plugin that provides similar functionality
  36. 36. 36 Reconstruction  Common Reconstruction Tasks – Reconfiguring Off-the-shelf Plugins & Themes – Rewriting Theme stylesheets and re-uploading graphics – Reconfiguring widgets – Reposting content
  37. 37. 37 Security (Re)Hardening  Reset users’ passwords  Change the MySQL database password  Update WordPress, Themes and Plugins to latest versions – May require renewal of support for Premium themes/plugins
  38. 38. 38 Beware of UTF-7 Encoding  From WordPress Admin go to Settings->Reading  Is this visible?  An attack has weakened WordPress’s character encoding settings to facilitate future XSS (Cross- Site Scripting) attacks.  Change this setting back to UTF-8
  39. 39. 39 Repairing Damage to Reputation  Remove Google warnings by submitting a reconsideration request in Google Webmaster Tools that outlines: – That you have disinfected your site – What you have done to prevent a recurrence, e.g. Updated software to address security vulnerabilities, installed a Web Application Firewall (WAF)  Inform users & readers of your site
  40. 40. 40 More Information  Wordfence’s article “How Attackers Gain Access to WordPress Sites” – https://www.wordfence.com/blog/2016/03/attackers-gain-access-wordpress-sites/  Google Webmaster’s help for hacked sites: – https://www.google.com/intl/en/webmasters/hacked/  Slides from My Previous Security Talks. Old but good  – Wordcamp GC 2011: • http://slidesha.re/tr2XA5 • Covers the “Three Pillars of Security”, the aims of attackers and other WordPress security plugins – WordCamp Sydney 2012: • http://www.slideshare.net/wordcampsyd/securing-your-wordpress-website-vlad-lasky-wordcamp- sydney-2012  Questions and Comments: – http://wpexpert.com.au/contact-us/

×