The Codex of Business Writing Software for Real-World Solutions 2.pptx
Ddos and mitigation methods.pptx
1. DDOS Attacks
and Mitigation Methods
Özkan Erdoğan
ozkan.erdogan@btpsec.com
Ms.C, CISA, CEH, ISO 27001 LA
BTPSec LTD
info@btpsec.com
Office:+44 203 2870040
+44 792 6112461
Address:5 Milton Grove, London UK
2. What is DOS & DDOS?
★ D = Distributed
○ DOS : focused on vulnerabilities, using single source
○ DDOS : overflow focused, using multiple sources
○ Target of attacks is to eliminate availability of the resource
4. Is it possible to mitigate Ddos attacks?
Our experience shows that its quite possible to mitigate ddos attacks. However, there are caveats such
that:
❏ Most ddos attacks come big in volume where it saturates your bandwidth . Attack volume > Target
network bandwidth (mbps).
These attacks can be handled by obtaining service from global anti ddos providers: e.g. Cloudflare,
Incapsula, Akamai etc.
❏ Other kinds of attacks are usually ineffective if we configure our network with correct measures.
7. Ddos Survey Results
61% loss of access to information
38% business stop
33% loss of job opportunities
29% reputation loss
26% insurance premium increases
65% Received security consultancy
49% More investments on IT
46% Started legal processes
43% Informed customers
36% Applied legal ways
26% Informed the media
● Spamhaus
● Chinese domain authority (.cn)
● Pohjola -Finland bank
● Nasdaq
● Bitcoin
● Bank of America
9. BOTNETs
➔ Controlled by Botnet herders
➔ Commanded via : Mirc, http(s), Tor (popular now)
➔ Injection methods: Wordpress, Joomla etc. old Windows systems are easiest
targets.
➔ Botnet members are targeted to be amongst data center systems.
10.
11. DDOS events
1. Spamhaus (DNS Amplification) 300gbps.
a. 11 Feb 2015: New NTP attack: 400gbps
2. Brobot (American Financial companies)
3. Chinese attacks
4. Russia: DDOS gangs
5. Syn reflection attacks are gaining a rise.
14. Basic DDOS Attacks
➔ Signature based attacks (Teardrop, Land, Smurf, Nuke,Fraggle vb)
➔ Volumetric attacks (legal and illegal attacks)
➔ Reflection (dns, syn)
➔ Application based attacks: e.g. Slow attacks
➔ Connection attacks
15. Protocols used in DDOS
➔ TCP/IP
◆ Tcp,udp, icmp,
◆
➔ Other (GRE, ESP etc)
➔ IPv4
➔ IPv6
➔ Application layer
◆ Http, dns, VOIP etc.
16. IP Spoofing (&How to detect it)
➔ uRPF- Unicast reverse path forwarding.
➔ Source IP of packet is compared to the FIB table in router and dropped if
routes are not the same.
➔ Authentication
➔ First packet drop, and let following packets go.
21. Syn Flood and Prevention
Attacker
ServerSyn
Syn
Syn
Syn
Syn-Ack
Syn-Ack
Syn-Ack
• Most popular ddos attack is syn flood.
• Protection method: Authentication and WL. (Whitelisting) (Syn
cookie vs. syn proxy)
• Syn reflection factor
• Syn flood from real IP addresses: TCP ratio mechanism
22. Syn-Ack Flood and Mitigation
Attacker
ServerSyn-Ack
Syn-Ack
Syn-Ack
Syn-Ack
• Protection: Check session table if syn-ack’s are real.
23. Ack Flood ve Mitigation
Attacker
ServerAck
Ack
Ack
Ack
• Protection: Check session table if ack’s are real.
24. FIN/RST Flood and Mitigation
Attacker
ServerFin/Rst
Fin/Rst
Fin/Rst
Fin/Rst
• Protection: Check session table if packets are real.
25. Udp Flood and Mitigation
Attacker
ServerUdp
Udp
Udp
Udp
• Udp is the most effective for ddos
• Protect method: Payload and Header.
(Fingerprint)
• Dest.port, source port, ttl, source/dest IP also
checked
• ACL
27. TCP Connection Flood & Mitigation
❏ Low rate attack (Protection: Number of connections are analyzed- Bot detection methods are used)
❏ TCP Null connection attack (No packets after handshake)
❏ Also check for rates of:
❏ New connections
❏ Total connections per
second
35. DNS Flood
➔ Is the target DNS: Authoritative DNS or cache DNS?
36. DNS Attacks- Continued
★ Dns Cache poisoning attack
★
★ Dns reflection attack
★
★ Dns query/repsonse attacks
37. DNS Query/Response Attacks
SP DNS
1. What is the IP for abc.google.com?
2. What is the IP for abc.google.com?
Attacker
3. IP= XXX.XXX.XXX =news.google.com
DNS Reply Flood
Attacker
38. DNS Cache Poisoning
SP DNS
1. What is the IP for abc.google.com?
2. What is the IP for abc.google.com?
Attacker
3. abc.google.com= x.x.x.x
DNS Reply
Attacker
• Domain info on Cache DNS servers are attempted
to be changed with the fake one.
• Attacker should guess the query id correctly.
(which is so easy if query id’s are not random)
DNS Reply
39. DNS Reflection
Open DNS
resolvers
1. What is the IP for abc.google.com?
2. What is the IP for abc.google.com?
Attacker
DNS Reply
• Attacker uses victim’s IP address as his source,
and sends a dns query to all known dns servers.
• Thousands of resolvers return the answer to the
victim and victim is Ddos’ed
DNS Reply
DNS authority
Victim
40. DNS Attacks
Conclusion:
➔ DNS attacks are very dangerous and can be performed with the least effort
and cost .
➔ Ddos attacks are on the rise every year and quite possible to be so in the
future.
➔ Udp and Dns based ddos attacks are the most effective protocols for ddos.
41. Methods To Protect Against DNS Ddos
Attacks
➔ Session control (Two way traffic)
➔ DNS proxy, caching
➔ DNS-Tcp Authentication
➔ First packet drop
➔ Domain name limiting
➔ Traffic limiting
42. An Effective Mitigation Technique:
Fingerprinting
Packet header and payload is analyzed to determine a fingerprint of attack.
45. NTP Amplification ( Attack multiplier 300x)
Can also use snmp for upto 600x , however snmp seldom allows
nonauthenticated clients
11 February 2015: New NTP
attack: 400gbps
46. Ddos Summary
● Extremely easy to attack ( Many free and user friendly tools)
● Impossible to be detected (If correctly hides)
● Big effects on the victim
● Attack types and methods are broad.
● Every application or service has its own ddos vulnerabilities
● ...Spoofing is possible and mostly costless
● ...AGAIN.. attack tools are free
