1 Honeypot, Botnet, Security Measurement, Spam Cliff C. Zou CDA /01/07

2 What Is a Honeypot? “A honeypot is a faked vulnerable system used for the purpose of being attacked, probed, exploited and compromised.”

3 Example of a Simple Honeypot Install vulnerable OS and software on a machine Install monitor or IDS software Connect to the Internet (with global IP) Wait & monitor being scanned, attacked, compromised Finish analysis, clean the machine

4 Benefit of Deploying Honeypots Risk mitigation:  A deployed honeypot may lure an attacker away from the real production systems (“easy target“). IDS-like functionality:  Since no legitimate traffic should take place to or from the honeypot, any traffic appearing is evil and can initiate further actions. Attack analysis:  Binary code analysis of captured attack codes  Spying attacker’s ongoing actions  Find out reasons, and strategies why and how you are attacked.

5 Honeypot Classification High-interaction honeypots  A full and working OS is provided for being attacked  VMware virtual environment  Several VMware virtual hosts in one physical machine Low-interaction honeypots  Only emulate specific network services  No real interaction or OS  Honeyd Honeynet/honeyfarm  A network of honeypots

6 Low-Interaction Honeypots Pros:  Easy to install (simple program)  No risk (no vulnerable software to be attacked)  One machine supports hundreds of honeypots Cons:  No real interaction to be captured  Limited logging/monitor function  Easily detectable by attackers

7 High-Interaction Honeypots Pros:  Real OS, capture all attack traffic/actions  Can discover unknown attacks/vulnerabilities Cons:  Time-consuming to build/maintain/analysis  Risk of being used as stepping stone  Must have a firewall blocking all outgoing traffic  High computer resource requirement

8 Honeynet A network of honeypots High-interaction honeynet  A distributed network composing many honeypots Low-interaction honeynet  Emulate a virtual network in one physical machine  Example: honeyd Mixed honeynet  “Scalability, Fidelity and Containment in the Potemkin Virtual Honeyfarm”, presented next week Reference: honeypot-forensics-slides.ppthttp:// honeypot-forensics-slides.ppt

9 What Is a Botnet? A network of compromised computers controlled by their attacker  Users on zombie machines do not know  Most home computers with broadband The main source for many attacks now  Distributed Denial-of-Service (DDoS)  Extortion  spam, phishing  Ad-fraud  User information: document, keylogger, …

10 How to Build a Botnet? Infect machines via:  Internet worms, viruses  virus  Backdoor left by previous malware  Trojan programs hidden in free download software, games …… Bots phone back to receive command

11 Botnet Architecture Bot controller  Usually using IRC server (Internet relay chat)  Dozen of controllers for robustness bot controller attacker bot controller

12 Botnet Monitoring Hijack one of the bot controller  DNS provider redirects domain name to the monitor  Still cannot cut off a botnet (dozen of controller)  Can obtain most/all bots IP addresses Let honeypots join in a botnet  Can monitor all communications  No complete picture of a botnet

13 Security Measurement Monitor network traffic to understand/track Internet attack activities Monitor incoming traffic to unused IP space  TCP connection requests  UDP packets Unused IP space Monitored traffic Internet Local network

14 Refining Monitoring TCP/SYN not enough (IP, port only) Distinguish different attacks  Low-interaction honeypots (honeyd)  Obtain the first attack payload by replying SYN/ACK  Used by the “Internet Motion Sensor” in U. Michigan Paper presented next…  High-interaction honeypots

15 Remote fingerprinting Actively probe remote hosts to identify remote hosts’ OS, physical devices, etc  OSes service responses are different  Hardware responses are different Purposes:  Understand Internet computers  Remove DHCP issue in monitored data  Paper presented later

16 Data Sharing: Traffic Anonymization Sharing monitored network traffic is important  Collaborative attack detection  Academic research Privacy and security exposure in data sharing  Packet header: IP address, service port exposure  Packet content: more serious Data anonymization  Change packet header: preserve IP prefix, and …  Change packet content

17 Why So Many Spam? No authentication/authorization in Receive unsolicited by design Sending fake is so easy  Shown in next slide Profit:  Takes a dime to send out millions spam  A few effective spam give back good profit  No penalty in spam (law, out-of-country spam)

18 Sample fake sending Telnet longwood.cs.ucf.edu 25 S: 220 longwood.cs.ucf.edu ESMTP Sendmail /8.13.8; … C: HELO fake.domain S: 250 Hello crepes.fr, pleased to meet you C: MAIL FROM: S: 250 Sender ok C: RCPT TO: S: 250 Recipient ok C: DATA S: 354 Enter mail, end with "." on a line by itself C: subject: who am I? C: Do you like ketchup? C:. S: 250 Message accepted for delivery C: QUIT S: 221 longwood.cs.ucf.edu closing connection

19 Current Major Spam Defense Signature-based filtering  Spamassasin, etc: based on keywords, rules on header… Blacklisting-based filtering  DNS black list, dynamically updated (Spamhaus) Sender authentication  Caller ID (Microsoft)  Sender Policy Framework (SPF)