Sucuri Webinar: How to clean hacked WordPress sites

HOW TO IDENTIFY AND FIX A HACKED WORDPRESS WEBSITEWEBINAR
Ben Martin| @sucurisecurity #AskSucuri
WEBINAR
How to
Identify and Fix
a Hacked
WordPress Website

KRISTEN THOMAS
Community Manager
Community Engagement Team
@kdthomas327

HOUSEKEEPING ITEMS
● Poll questions on your screen
● Q&A
● Place questions in Q&A box
● Ask questions right away
● Use #AskSucuri on Twitter to engage
● Questions will be answered and delivered post-webinar
● Brief survey at the end of the presentation
● Presentation video

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• Remediation Team Lead at Sucuri Inc.
• Security geek, malware slayer, music
producer
BEN MARTIN

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Victoria, BC, Canada

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Ben & WordPress
• 6 years working in cybersecurity and IT / software
• Has cleaned thousands of WordPress (and other) websites
• Helps to identify new malware campaigns and stop hacks
• Spoke at WordCamp Vancouver, Toronto and Portland

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Overview of Sections
• Signs that your website has been pwned
• Find and remove the source of the infection
• What to do after a hack

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Have I been pwned?
Tell tale signs that your website has been compromised

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How can I tell if I’ve been hacked?
• #1 – Your website has been blacklisted
• Common/major vendors include Google, Yandex, Norton,
McAfee, Sophos, MalwareBytes, Sucuri...
How to tell?
• Head on over to virustotal.com and scan your
domain
• https://sitecheck.sucuri.net
• Your visitors may report security warnings

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• #2 – You see spam in Google search results for your
website
• Pharmaceuticals, adult content, torrent downloads, NFL
jerseys, essay writing, cat food, cheap cheap cheap, knock-
off designer goods, cheap hotels, more pharmaceuticals...
How to tell?
• ‘This site may be hacked’ in Google
• Bogus/spam content in your site description
• Search site:mywebsite.com and check results

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• #3 – Traffic to your website is redirected elsewhere
• Spam sites, exploit kit landing pages, adult websites,
ransomware, malicious .ru / .su domains, phishing pages,
other hacked sites
How to tell?
• When you try to access your site, you end up
elsewhere
• Your visitors may report weird behaviour of your site
• Many redirects are conditional (ie: only for mobile
devices, only for some operating systems, only with
some specific referrers, etc...)

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• #4 – Weird pop-ups or other strange behaviour
How to tell?
• Unexpected ads, new tabs opening up, pop-ups
and pop-unders
• Your visitors may report weird behaviour of your
site
• Sometimes only happens on certain devices or
under certain conditions

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• #5 – SiteCheck flags malware
• Head on over to https://sitecheck.sucuri.net
How to tell?
• It will flag malware, spam, redirects, etc
• Disclaimer: 100% accuracy is not realistic and not
guaranteed
• A remote scanner can only flag what is displayed on
the website.
• Best to monitor file system as well for malware as
well which is included in our services

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• #6 – Your website looks something
like this:
How to tell?
• Pretty self-explanatory

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So now what do I do?
Some helpful pointers on fixing the hack

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Basic Overview: Only so many places to hide
Process of Elimination
• Core files
• Plugins
• Themes
• Database
• .htaccess
• Ad networks
• The server itself

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Tools of the trade: Add these to your tool-belt
Security and Development Tools
• Sucuri-scanner WordPress plugin
• Filezilla (FTP client)
• NoScript (Script blocker)
• VirtualBox (Virtualization tool)
• ublock Origin (Ad blocker)
• PHPMyAdmin or Adminer (database management)
• User Agent Switcher
• Support forums (ie: wordpress.org)

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Heads up: Back up your website first!
Modifying files/database can cause damage
if any mistakes are made
• Make a website backup before making any changes
• This includes your file structure and database
• These can be safely stored as a .ZIP somewhere, but do not store
it on the server because it can be a security risk

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Step 1: Core Files
Modification of core files is a
common way to infect a
website
• Check the integrity of your core files (sucuri-
scanner, diff, etc...)
• Check for recent modifications of core files
• Replace core files with fresh copies (wp-
includes, wp-admin, index.php, etc...)
• Common culprits are index.php, wp-
load.php, ./wp-includes/nav-menu.php ...

Example file: Infected ./wp-load.php

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Step 2: Theme files
Very common place to lodge malware
• Efective spot to place malware for nefarious purposes
• Check files on server for anything recently modified in
your theme (see image --->)
• Common culprits are index.php, header.php, footer.php,
functions.php, 404.php ...
• Hacked/freemium/nulled themes should be avoided at all
costs
• Try temporarily switching to a freshly downloaded clean
theme (like twentysixteen or other defaults) to see if
problem goes away
• Not sure what to do? Remove/replace ALL the theme files
with fresh copies

Example file: Infected header.php

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Step 3: Plugins
Bogus or hacked plugins can
be source of infection
• Check every single plugin within ./wp-
content/plugins
• Check plugin files that were recently modified
(Filezilla)
• Temporarily disable your plugins and re-scan
or re-visit your site to see if the problem goes
away
• Hacked/freemium/nulled plugins should be
avoided at all costs
• Not sure what to do? Remove/replace ALL the
plugin files with fresh copies

Example: Out of date plugins

Example of bogus
plugin:
./wp-content
/plugins/WPCoreSys

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Step 4: Database
Spam, iframes, hidden div
tags...
• The database is where all the content of
your posts/pages/settings are stored
• Common place for attackers to place spam
links
• Can add malicious iframes to posts/pages
• Try searching your database for spam
terms (viagra, cialis, cheap, etc...)
• Spam you see in Google or flagged by
sitecheck.sucuri.net is often hiding here

Example: display:none spam in database
Visitors cannot see, but search engines can

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Step 5: .htaccess
Can be used or abused
• Common location for malicious redirects to
be placed
• Can redirect whatever traffic you want to
wherever you want
• Can also be used to add additional
security rules to your website
• Default WordPress .htaccess is 236 bytes
in size
• Not a bad idea to set file as read-only

Example file: Spammy/hacked .htaccess

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Step 5: Advertising networks
Can be a source of great woe
and misfortune
• Crappy/cheap ad networks are commonly
related to malvertizing
• No server is 100% secure
• Integrating third party content is always a
risk
• Best to stick with reputable advertising
networks
• If you are using an ad network that has been
compromised, you need to disable the
network completely until the problem is
gone

Example code: Bogus/compromised ad
networks.
Code is placed at bottom of all wp_posts and redirects visitors to
spam sites

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Step 6: The server itself
Not as common, but still happens
• Sometimes the server on which your website resides is
itself rooted
• Choose your hosting provider carefully
• What will your host do if your website or server is
compromised?
• VPS is a good solution for a safer, private server
• If your server is infected, it is possible to clean it but
the best option is to migrate whe website to a new
server
• Do not re-use ANY passwords

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Step 7: Backdoors
The hardest part!
• If backdoors are inserted on your site the
attackers will still have access, even if you delete
the other malware
• Backdoors are always coupled with main payload
• New backdoors written all the time, lots of variety
• Check which files were recently modified on your
server
• Check logs to see any strange files being
accessed directly (especially from weird IP’s)

Example file: Backdoor in theme’s footer.php

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Pro Tip: Some More Helpful Resources
Can help to determine problem:
• https://sitecheck.sucuri.net
●
Website malware scanner
• https://aw-snap.info
●
Can find redirects, spam, malvertizing
• https://www.webpagetest.org
●
See what’s loading on your website/server
• https://portswigger.net/burp
●
A more advanced web application tool
• http://ddecode.com and https://unphp.net
●
Useful for decoding malware and obfuscated code

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The malware is gone, now what?
Gotta’ protect those Interwebs

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Remember: They will be back
• Much like an e-mail account targeted
by spammers, you can’t just hope the
problem will go away
• When attackers identify
vulnerable/easy site to hack, they will
keep hacking it over and over
• Attackers know that root problems
are rarely addressed
• Need to take proactive steps to
prevent re-infection

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Step 1: Update all the things!
Out of date software is leading
cause of infection
• Update WordPress, all plugins, themes
• Make sure your server is up to date (cPanel, apache,
etc...)
• Basic and proactive website maintenance is first line
of defense
• This is a constant process, never let your guard down

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Step 2: Change all the passwords!
Easy to guess/crappy/compromised
passwords is #2 reason for website
compromise
• Change all admin passwords to your site
• That includes wp-admin, FTP/SFTP, cPanel, hosting,
database, basically everything
• Consider using password manager like LastPass
• The harder it is for you to type/remember the harder it
will be to brute force

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Step 3: Review who has access!
Have as few administrator
users as absolutely necessary
• This applies to everything from wp-admin, FTP, any
other connection mechanism
• The more admin accounts you have, the more likely
something will go wrong
• Ensure that all passwords are strong and complex
• Perform admin work from admin account, and have
separate account for blog posting etc.

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Step 4: Clean your kitchen!
Decrease the attack surface
• Remove unused plugins and themes from the server
• Remove any old versions of your website, dev sites and
backups of your website from your server and store
them somewhere else
• Remove unnecessary administrator accounts
• Exercise ‘least privilege’ only grant minimum privileges
necessary for people to perform work

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Step 5: Scan your box!
If your laptop/workstation is
pwned, that could be the source
of the attack
• Regularly scan your computer for
viruses/malware
• Use a good, reputable anti-malware program
• Don’t administer your website from a public
computer
• Use encrypted protocols such as SFTP when
accessing your website (encryption is your
friend...)

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Step 6: Backups regimen!
A clean, functional backup is your
best friend on a rainy day
• Perform regular backups of your website
• DO NOT store your backups ON YOUR PRODUCTION
SERVER
• Backups should be stored off-site
• There are many online services that can perform
regular backups for you (we offer one and it’s very
affordable ☺ )

Example: Sucuri backups dashboard

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Step 7: Harden your site!
WordPress out of the box can
use a lot of tweaking
• Disable .PHP execution from /images
directories as well as ./wp-content/uploads
• Disallow file edit function in wp-config.php
• Use a security plugin if you don’t already
• Make sure reporting/logging is functional

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Step 8: Use a WAF!
Web Application
Firewalls are the best
defense against the bad
guys
• Sanitizes all traffic to your website
• Prevents XSS, DDoS, etc...
• Vulnerable software will be virtually
patched and protected
• Speed/performance of website will
increase

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• Questions?
• Tweet us @sucurisecurity #AskSucuri
THANK YOU!

Sucuri Webinar: How to clean hacked WordPress sites

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