Content delivery network and web application firewall

CONTENT DELIVERY NETWORK AND
WEB APPLICATION FIREWALL
A Double Whammy for Hackers?

MY BRIEF CREDENTIALS
 Principal IT Consultant, CISSP
 eBay Bug bounty award.
 0-day full CV dump vulnerability on a major job
search site.
 Work in Silicon Valley California as a software
developer during Dot COM boom days.
 Email: andrewchong2000@gmail.com

DISCLAIMER
 The information presented does not reflect the
opinion of my current employer.
 The views and opinions expressed are purely from
my personal research.
 Any product claim, statistic, quote or other
representation about a product or service should be
verified with the manufacturer or provider.

MAIN TOPICS
 How does CDN and WAF help prevent cyber attack
for FI?
 Discussing the defacement of Malaysia Airlines
Website even though both CDN and WAF were in
place.
 Techniques to close the gap and building strengths
for the future.

REMINDER
 This presentation is not:
 To tell you to be compliant to MAS TRM guidelines which you already
knew.
 To tell you the “defense-in-depth” theories which you already knew.
 To tell you the dangers and motivation of Cyber Attacks, DDoS
attacks, Malware which you already knew.
 To tell you the to give users awareness training which you are
already knew.
 To tell you how to create governance process which you already
knew.
 Blah Blah...
 The objective is not to bored all the Ninjas here! 

PREPARING A DDOS ATTACK DEFENCE
 Purchase an On-Premise DDoS Mitigation Appliance
 E.g. Fortinet, Juniper Network, CISCO Guard
 Purchase a DDoS Mitigation Service from your ISP
 E.g. Clean-Pipe service, Level3
 Purchase a DDoS Mitigation Service from a specialized
mitigation service provider
 E.g. Akamai, Incaptula, CloudFlare, DOSarrest, ARBOR
Examples of CDN+WAF,
or “Scrubbers”
technology providers

AGENDA
1. Preparing a DDoS Attack Defence
2. Traditional Architecture
3. What is a Content Delivery Network (CDN)?
4. CDN Architecture
5. Key Benefits of Enterprise CDN
6. Key Benefits of Web Application Firewall (WAF)
7. CDN and WAF Architecture
8. WAF Weakness
9. CDN Weakness
10. Case Study: Malaysia Airlines incident (26-Jan-15)
11. Case Study: Lenovo incident (25-Feb-15)
12. DNS Hijacking Prevention Best Practices
13. Questions to ask your Domain Registrar
14. CDN Security Protection Best Practices

TRADITIONAL ARCHITECTURE
 So how to solve it?
 Solution: Servers are always close to you!

WHAT IS A CONTENT DELIVERY NETWORK
(CDN)?
 A Content Delivery Network (CDN) is a network of
servers hosted by a service provider in multiple
locations of the world so that the content could
always be served from a server that is nearest to
the consumer requesting for it.
 A CDN consists of two key components:
 The Origin Server(s) – the content source server.
 Cache / Edge servers – the servers that the client see
and request for content.

CDN ARCHITECTURE
 CDN Network Architecture

CDN ARCHITECTURE
 CDN uses DNS CNAME record to hide your origin (source)
server.
 www.dbs.com.sg A record is 23.204.171.241
 The “A” in “A” record stands for Address. “A” record is
used to find the address of a computer connected to the
internet from a name.

CDN ARCHITECTURE
 23.204.171.241 belong to Akamai.

CDN ARCHITECTURE
 po.dbs.com.sg is the SOA or primary DNS server
 SOA stands for Start Of Authority

CDN ARCHITECTURE
 CDN can also protect your primary/master DNS server (SOA)

CDN ARCHITECTURE
 Client request logo.png on images.mydomain.com
 The DNS system finds the CNAME and redirects the request to the CDN.
 If logo.png is not found or expired in the CDN, it is requested from the Origin
server and refresh the cache in the CDN.
 The CDN response to the Client request with the logo.png.

CDN ARCHITECTURE
 Request Flow: DNS  CDN  Origin
 CDN have the ability to “pull” content from their origin server
during HTTP requests in order to cache them.
 Beside GET request, CDN can also proxy POST requests.
 Do check with your CDN provider to block PUT, TRACE,
DELETE, CONNECT, which are unsafe HTTP methods.

KEY BENEFITS OF ENTERPRISE CDN
 Faster site performance
 High availability
 Web application firewall (WAF)
 DDoS protection
 DNS DDoS and attack protection
 Virtually real-time statistics
 CDN vendor threats monitoring (managed service)

KEY BENEFITS OF ENTERPRISE CDN
 Other Hidden Benefits!
 CDN vendor manage your SSL certificates lifecycle.
 Wildcard SSL certificates are implemented on the edge servers.
 “Free” threats consultation from CDN vendor.
 Lessen your company cyber-ops workload
 Less need to trigger technical control to block attackers
 Less need to escalate threats to internal teams
 Lessen the effort to fine tune WAF configurations as compared to
implementing your own WAF.
 Reduce overall operation cost.

KEY BENEFITS OF WEB APPLICATION FIREWALL
(WAF)
 “Most” Layer 7 attacks can be blocked before reaching the
web server.
 A “fast” solution to block vulnerable applications from attacks.
 Newly discovered application threats like “Path Relative
Stylesheet Import” (PRSSI) vulnerabilities can be protected by
updating the WAF signatures.
 Block automated scanners using signatures and rate control.
 Legacy applications can be protected while the application
take time to be upgraded.

WAF WEAKNESS
 WAF is not possible to protect all layer 7 attacks.
 E.g. Application business logic bypass
 WAF uses regular expressions to block matching attack
patterns.
 WAF regex needs to be constantly fine tune and improve to
block clever attacks.
 Due to the bad coding of the application design, specific WAF
rules are often disable or set it to “warning” mode in order to
allow the application to work.

WAF WEAKNESS
 WAF can be bypassed given the attack enough time to figure
out.
 Example: Blind SQL Injection WAF regular expression bypass
 Substring keyword is block. However, left and right keywords are ok!
 Block
 and+ascii(substring((SELECT%20db_name()),1,1))%3d70
 Bypass
 and+ascii(right(left((SELECT%20db_name()),1),1))%3d70
 and+ascii(right(left((SELECT%20db_name()),2),1))%3d70
 ...

CDN WEAKNESS
 Normal domain name request
 DNSIPCDNORGIN

CDN WEAKNESS
 What if? DNSIPCDNORIGIN
 Just because your origin server's IP address is no longer advertised
over DNS, it's still connected to the internet!
 If your IP address is not kept secret, attackers can bypass the CDN
to attack your servers directly!

CDN WEAKNESS
 Attacking the Origin Server
Weak Point DDoS
Origin IP

CDN WEAKNESS
 Common default Origin naming by CDN providers
 ORIGIN.<domain name>
 ORIGIN.<sub>.<domain name>
 DIRECT.<domain name>
 <domain name>.CDN.<CDN domain name>
 Try typo error naming:
 ORIGN
 ORGIN

CDN WEAKNESS
 Akamai debug HTTP request pragma headers
 Source: http://mesmor.com/2012/03/18/akamai-pragma-debug-headers/
 Pragma: akamai-x-cache-on, akamai-x-cache-remote-on,
akamai-x-check-cacheable, akamai-x-get-cache-key, akamai-
x-get-extracted-values, akamai-x-get-nonces, akamai-x-get-
ssl-client-session-id, akamai-x-get-true-cache-key, akamai-x-
serial-no
 curl -s -I -H "Pragma: akamai-x-get-true-cache-key "
http://www.malaysiaairlines.com

CDN WEAKNESS
 HTTP/1.1 200 OK
 Date: Tue, 10 Feb 2015 04:43:34 GMT
 ETag: "12fc58b-2b88d-50eb3ec99f1c0"
 Server: Apache
 X-Cache: TCP_IMS_HIT from a23-220-203-15.deploy.akamaitechnologies.com
(AkamaiGHost/7.1.0.2-14656242) (-), MISS from 10.88.3.70, MISS from 10.88.3.70
 X-Serial: 1456
 X-Cache-Key: /L/1456/211307/1h/origin.www.malaysiaairlines.com/my/en.html
 Content-Type: text/html; charset=UTF-8
 Cache-Control: no-cache
 Last-Modified: Tue, 10 Feb 2015 04:00:15 GMT
 X-Frame-Options: SAMEORIGIN
 Proxy-Connection: Keep-Alive
 X-True-Cache-Key:
/L/origin.www.malaysiaairlines.com/my/en.html
 X-Check-Cacheable: YES
 X-Akamai-Session-Info: name=AKA_PM_BASEDIR; value=
 X-Akamai-Session-Info: name=AKA_PM_CACHEABLE_OBJECT; value=true
 X-Akamai-Session-Info: name=AKA_PM_DEV_CHAR_IS_MOBILE; value=false;
full_location_id=is_mobile
 X-Akamai-Session-Info: name=AKA_PM_FWD_URL; value=/my/en.htm
Default and
guessable origin
name!

CDN WEAKNESS
 CDN providers also provide customers with staging CDN platform.
 CDN staging platforms allows customers to test the changes before
implementing on production CDN.
 Theoretically, staging platform will be less “robust” than the
production platform.
 CDN staging platform may not be monitored at all! A good way for
hackers to test for vulnerabilities without being caught or alerted.
 To find the staging platforms url, just google it and guess it!
 Or simply sign-up for the CDN provider service to find out! 

CASE STUDY: MALAYSIA AIRLINES INCIDENT (26-JAN-15)
 Source: http://www.theguardian.com/world/2015/jan/26/malaysia-airlines-
website-hacked-by-lizard-squad

 Name Server (NS) is akam.net (using Akamai CDN! Holy S***)
 Start Of Authority (SOA) is barbara.ns.cloudflare.com
 Why 2 CDN vendors? Really?

 HTTP Response Header
 Server: LIZARDSQUAD
 Who will bother to change the server banner after a
defacement? (e.g. modify httpd.conf, registry)
 Most likely it is a DNS hijacking attack!

 Source: http://www.computerworld.com/article/2874928/malaysia-airlines-
claim-dns-hijacked-site-not-hacked-but-attackers-threaten-data-dump.html

 Source: http://www.washingtonpost.com/news/morning-
mix/wp/2015/01/26/lizard-squad-hacks-malaysia-airlines-claiming-link-to-
islamic-state/

 Phishing attack possible cause.
 Source: http://www.tnooz.com/article/explainer-malaysian-airlines-
website-attack/

 After site went back to normal, the DNS records are as follows:
 SOA is now rusa.skali.com.my
 Is this the correct SOA?
 Or they’ve move out of Cloudflare?

 Search historical DNS records using DNSHistory.org
 Malaysiaairlines.com SOA is rusa.skali.com.my!

 Malaysiaairlines.com domain Registrar is Webnic.cc
 Webnic.cc got compromised? Most likely... But no public news to
confirm.

CASE STUDY: LENOVO INCIDENT (25-FEB-15)
 Source: http://www.theguardian.com/technology/2015/feb/26/lenovo-website-
hacked-and-defaced-by-lizard-squad-in-superfish-protest

 Source: http://www.eweek.com/security/lenovo.com-hacked-but-soon-
restored-after-intervention-by-cloudflare.html

 Source: https://twitter.com/lizardcircle

 The EPP Authorization Code is basically a password for the domain
and is one of the most powerful safeguards against unauthorized
transfers of a domain name.
 In other words, EPP Authorization Codes are an extra security
measure ensuring that only the actual domain name owner is able to
initiate an outgoing domain transfer towards another Registrar
Client locked
EPP code

 Source: https://twitter.com/lizardcircle
 Lenovo emails has also been hijacked due to the DNS hijacked.

 Source: http://krebsonsecurity.com/2015/02/webnic-registrar-blamed-for-
hijack-of-lenovo-google-domains/

 Source: http://krebsonsecurity.com/2015/02/webnic-registrar-blamed-for-
hijack-of-lenovo-google-domains/
Rootkit!

 What is a Rootkit?
 A Rootkit is a stealthy type of malicious software, designed to
hide the existence of certain processes or programs from
normal methods of detection and enable continued privileged
access to a computer.
 Damages: A Rootkit might covertly steal user passwords and
sensitive data or conduct other unauthorized activities.

 Webnic registrar offline for around 5 days after the incident.

DNS HIJACKING PREVENTION BEST PRACTICE
 Major DNS Hijacking incidents

 DNS Hijacking aka Domain Theft is the process by
which the registration of a currently registered
domain name is transferred without the permission
of its original registrant, generally by exploiting a
vulnerability in the domain name registration
system.

 Registrar Clients locks:
 Purpose: To prevent unauthenticated changes.
 clientUpdateProhibited
 clientTransferProhibited
 clientDeleteProhibited
 This is useless when the attacker has obtain the credentials to
a registrar account.
 Source: https://blogs.akamai.com/2015/01/dns-hijacking-dangers-and-
defenses.html

 Registrar Servers locks:
 Purpose: The registrar will contact the previously agreed upon admin
contact to verify the changes.
 Requires call back to a specified phone number
 Only certain individuals can make changes
 serverUpdateProhibited
 serverTransferProhibited
 serverDeleteProhibited
 Source: https://blogs.akamai.com/2015/01/dns-hijacking-dangers-and-defenses.html

 After the incident, Malaysia Airlines implemented both
Registrar Client Lock and Registrar Server Lock.

 After the incident, Lenovo implemented both Registrar Client
Lock and Registrar Server Lock.

 Most domains implement Registrar Client Lock only to avoid inconvenience
when there is a need for fast turnaround time.
 Example: www.dbs.com.sg

QUESTIONS TO ASK YOUR DOMAIN REGISTRAR
 Choose a reputable Domain Registrar. Do your research by
asking the following questions:
 Q1: What are my authentication options?
 Q2: How will authorized changes be verified?
 Q3: Can I lock changes to a call back number?
 Q4: Backup plan when primary authentication method fails?
 Q5: Can the above be circumvented via API, Rookit or portal?

CDN SECURITY PROTECTION BEST PRACTICES
 Don’t use guessable origin domain name. The attacker can guess
the origin system DNS record to bypass the controls. Or using
Shodan (http://shodanhq.com).
 E.g. origin.www.<domain name>

 Disable CDN debugging features. The debugging information can be
used by attacks to design a DDoS attack.

 Only allow your Origin server to communicate with your CDN servers
by white-listing the CDN servers on your firewall.

 Only allow your Primary DSN server to communicate with your CDN
DNS servers by white-listing the CDN DNS servers on your firewall.

 To prevent Direct-to-Origin attacks
 Subscribe to your ISP Clean-Pipe service or to a Scrubber service
provider.

THANK YOU!
References:
 https://www.incapsula.com/blog/
 https://blogs.akamai.com/2013/08/bypassing-content-delivery-
security.html
 https://blogs.akamai.com/2015/01/dns-hijacking-dangers-and-
defenses.html
 https://blogs.akamai.com/2014/06/fresh-wave-of-online-
extortion-attacks-underway.html
 https://blogs.akamai.com/
 https://blog.cloudflare.com/
 http://mesmor.com/2012/03/18/akamai-pragma-debug-
headers/

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