CIT 480: Securing Computer Systems. Incident Response and Honeypots

Transcription

1 CIT 480: Securing Computer Systems Incident Response and Honeypots

2 Incident Response What is an Incident? Phases of Incident Response 1. Preparation 2. Identification 3. Containment 4. Damage Assessment 5. Preserve Evidence 6. Eradication 7. Recovery 8. Follow-up

3 What is an Incident? Violation of security policy: Unauthorized access of information Unauthorized access to machines Embezzlement Virus or worm attack Denial of service attacks spam or harassment

4 Detecting an Incident Catching perpetrator in the act Unauthorized logins, network connections, NIDS alerts. Noticing unauthorized system changes. Notification from another entity Customer Partner Law enforcement Victim of attack launched from your IP range Strange activities on system: crashes, random reboots, slow performance.

5 Incident Response Restoring system to satisfy site security policy Phases: 1. Preparation for attack (before attack detected) 2. Identification of attack 3. Containment of attack (confinement) 4. Damage assessment 5. Preserve evidence (if necessary) 6. Eradication of attack (stop attack) 7. Recovery from attack (restore system to secure state) 8. Follow-up to attack (analysis and other actions)

6 Preparation 1. Configure intrusion detection systems. 2. Determine your response goals. 3. Document incident response procedures. Who to contact? What to do? 4. Organizing a CSIRT Finding and training personnel. Hardware/software necessary for investigation.

7 Incident Response Goals 1. Identify what happened. 2. Contain intrusion to prevent further damage. 3. Recover systems and data. 4. Prevent future intrusions of same kind. 5. Investigate and/or prosecute intrusion. 6. Prevent public knowledge of incident.

8 Identification Who/what reported incident. Date and time of the incident. Nature of the intrusion. What level of unauthorized access was attained? Is it known to the public? Hardware/software involved How critical are the affected systems? Assemble CSIRT Team membership may vary based on nature of incident

9 Containment Limit access of attacker to system resources. Containment method depends on criticality of systems and extent of intrusion. Monitoring intruder Reducing intruder s access Deception De-activating the affected account Need to kill active processes too Blocking access to system via firewall Pulling network/phone cable Powering down system

10 Monitoring Records attacker s actions; does not interfere with attack: Idea is to find out what the attacker is after and/or methods the attacker is using. Problem: attacked system is vulnerable throughout Attacker can also attack other systems. Example: type of OS can be derived from settings of TCP and IP packets of incoming connections Passive IDS tools like Bro and p0f work this way. Analyst draws conclusions about source of attack.

11 Reducing Access Reduce protection domain of attacker. Problem: if defenders do not know what attacker is after, reduced protection domain may contain what the attacker is after. Stoll created document that attacker d/led. Download took several hours, during which the phone call was traced to Germany.

12 Deception Honeypot: a system designed solely for intruders to attack in order to accomplish one or more of the following goals. Also known as a honeynet. 1. Detect intrusions with very few false positives, since legitimate users have no reason to access honeypot. 2. Monitor attacker activities to determine targeted assets, origin, motivation, capabilities, etc. 3. Waste intruder time attacking honeypot, so that defender has time to respond to incident.

13 Low Interaction Honeypots honeyd: responds to probes on a set of unused IP addresses via shell scripts that can return banners for simple scans like nmap sv. nepenthes: emulates vulnerable Windows services to collect exploits and malware. Dionaea: scriptable honeypot designed to be able to emulate wide variety of vulnerable services to collect exploits and malware. Fakenet: simulates DNS, HTTP, HTTPS to dynamically analyze malware. Returns reasonable responses to malware requests.

14 Medium Interaction Honeypots Kippo is a medium interaction ssh honeypot designed to log brute force attacks and attacker shell commands. Inspired by Kojoney, a LI ssh honeypot. Fake filesystem with the ability to add/remove files. Possibility of adding fake file contents so the attacker can 'cat' files such as /etc/passwd. Only minimal file contents are included. Saves files downloaded with wget for later inspection Deception: ssh pretends to connect, apt-get pretends to install, etc.

15 High Interaction Honeypots

16 Honeymonkey Thug Client Honeypots Strider Microsoft Research project. Network of VMs running IE crawling the web in search of malicious sites that attempt to exploit browsers and distribute malware. Multiple versions of Windows and IE used. Low interaction client honeypot. Emulates multiple browsers and OSes.

17 Honeytokens A honeytoken is data that is designed solely for attackers to abuse. Any access to the data is an indication of unauthorized use. Attempts to download honeytoken files or database records can be identified by NIDS. Medical record systems will sometimes create fake records for celebrities and politicians. Mailing lists may contain addresses published nowhere else that point to accounts that accept mail and record sender information. Maps contain fake streets, towns, or islands to identify when competitors copy the map.

18 Damage Assessment: Data System date and time when assessment began. List of users currently logged in. Time/date stamps for filesystem. List of processes List of open network sockets Associated applications Associated systems System configuration files. Log and accounting files. System date and time when assessment complete.

19 Preserve Evidence In-depth live system investigation. Construct a bit-level copy of entire hard disk or partition for forensic examination. Create image in single-user mode if possible: md5sum /dev/hda dd if=/dev/hda conv=noerror,sync ssh desthost cat >disk.img desthost> md5sum disk.img

20 Eradication 1. Do nothing. 2. Kill attacker s processes and/or accounts. 3. Block attacker s network access to system. 4. Patch and repair what you think was changed, then resume operation. 5. Investigate until root cause discovered, then restore system from backups and patch security holes. 6. Call law enforcement before proceeding further.

21 Follow-Up 1. File reports with law enforcement, vendor, or regulatory agency. 2. File insurance claims if relevant. 3. Notify administrators of other affected systems. 4. Disciplinary actions against employees for internal attacks. 5. Update security of computer networks/systems. 6. Review handling of the incident. 7. Update incident handling policy/training.

22 Counterattacking Use legal procedures Collect chain of evidence so legal authorities can establish attack was real. Check with lawyers for this Rules of evidence very specific and detailed. If you don t follow them, expect case to be dropped. Technical attack Goal is to damage attacker seriously enough to stop current attack and deter future attacks. Active Defense Harbinger Distribution Linux.

23 Consequences 1. Counterattack may harm innocent party. Attacker may have broken into source of attack or may be impersonating innocent party. 2. Counterattack may have side effects. If counterattack is DoS, may block legitimate use of network. 3. Counterattack antithetical to shared use of network. Counterattack absorbs network resources and makes threats more immediate. 4. Counterattack may be legally actionable.

24 Example: Counterworm Counterworm given signature of worm. Counterworm spreads rapidly, deleting all occurrences of original worm. ex: Welchia/Nachi hunts Blaster/MyDoom worms. Issues Can counterworm delete only targeted worm? What if infected system gathering worms for research? How do originators of counterworm know it will not cause problems for any system? And are they legally liable if it does?

25 Key Points 1. Incident response procedure. 2. Prepare for an incident before one occurs. 3. Don t trust the affected system in any way. 4. Contain, then prepare detailed response. 5. Legal issues of counterattacks. 6. Use honeypots to deceive attackers 1. Goals: intrusion detection, monitoring, slow 2. Interaction levels: low, medium, high 3. Honeyclients and honeytokens

26 References 1. Matt Bishop, Introduction to Computer Security, Addison-Wesley, N. Brownlee and E. Guttman,, RFC Expectations for Computer Security Incident Response, CERT, Computer Security Incident Response Team (CSIRT) FAQ, 4. William Cheswick, Steven Bellovin, Steven, and Avriel Rubin, Firewalls and Internet Security, 2 nd edition, Addison-Wesley, Fraser (ed.), RFC Site Security Handbook, Garfinkel, Simson, Spafford, Gene, and Schartz, Alan, Practical UNIX and Internet Security, 3 rd edition, O Reilly & Associates, Kevin Mandia, Chris Prosise, and Matt Pepe, Incident Response & Computer Forensics, 2 nd edition, McGraw-Hill, 2003.

27 Released under CC BY-SA 3.0 This presentation is released under the Creative Commons Attribution-ShareAlike 3.0 Unported (CC BY-SA 3.0) license You are free: to Share to copy and redistribute the material in any medium to Adapt to remix, build, and transform upon the material to use part or all of this presentation in your own classes Under the following conditions: Attribution You must attribute the work to James Walden, but cannot do so in a way that suggests that he endorses you or your use of these materials. Share Alike If you remix, transform, or build upon this material, you must distribute the resulting work under this or a similar open license. Details and full text of the license can be found at