Digital Forensics Dr. Bhavani Thuraisingham The University of Texas at Dallas Network Forensics - III November 3, 2008

Outline l Network Forensics l Performing Live Acquisitions l Standard procedures for network forensics l Network tools l Honeynet project l Review of paper by Iowa State l Presentation by PhD Student Clay Woolam on TCPDump analysis l References: - Chapter 11 of Textbook - Paper: raphs.pdf raphs.pdf

Network Forensics l Network Forensics is the process of collecting and analyzing raw network data and then tracking network traffic to determine how an attack took place l When intruders break into a network they leave a trail. Need to spot variations in network traffic; detect anomalies l Network forensics can usually help to determine whether network has been attacked or there is a user error l Examiners must establish standards procedures to carry out forensics

Securing a Network l Need measures to secure a network and prevent breaches l Apply patches; User a layered network defense strategy l NSA (National Security Agency) ahs developed DiD Defense in Depth) and has three models of protection - People, Technology, Operations - People: Employees are trained well - Technology: Strong network architecture and testing tools - Operations: applying security patches, anti-virus software, etc.

Performing Live Acquisitions l Insert bootable forensics CD in the suspect system l Keep a log of all the actions l Send collected information to a network drive l Copy the physical memory l Determine if root kit is present; access system’s firmware, - - l Get forensics hash value of all files

Performing Live Acquisitions: Windows l Setup NetCat listener to send the forensics data l Load Helix CD in the CD-ROM drive l Click appropriate buttons – System Information; Glad arrow etc l Click Acquire Live Image if Widows System l Connect to NetCat listener to send the collected data (e.g., enter IP address of NetCat listener) l Click Incidence Response Tools l Click on appropriate tools to collect data

Standard procedures l Standard installation image, hash schemes (e.g., MD5, SHA-1) l Fix vulnerabilities if intrusion is detected l Retrieve volatile data (RAM, processes) l Acquire compromised drive and make forensics image of it l Compare forensics image and standard image and determine if anything has changed

Network Logs l Network logs record traffic in and out of network l Network servers, routers, firewalls record activities and events that move through them l One ways is to run Tcpdump l When viewing network log, port information can give clues about suspicious activity l Use network analysis tool

Network Tools l Network Forensics tools help in the monitoring of the network l Example: the records that Ps tools generate can prove that an employee ran a program without permission l Can also monitor machines/processes that may be harmful l Problem is the attacker can get administrator rights and start using the tools l Chapter 11 discusses tools for Windows and Linux

Packet Sniffers l Devices or software to monitor (sniff) traffic l TCP/IP sniffers operate at the Packet level; in OSI operates at the Layer 2 or 3 level (e.g. Data link or Network layers) l Some sniffers perform packet captures, some perform analysis and some perform both l Tools exist for examining (i) packets with certain flags set (ii) headers (iii) IRC chats

Honeynet project l Honeynet project was established to make information about network attacks and solutions widely available l Objectives: Awareness, information, tools l Attacks: distributed Denial of Service, Zero day attacks l Honeypot is a computer set up to lure attackers l Honeywalls are computers set up to monitor what is happening to the honeypots in the network

Example Prototype System: Iowa State University l Network Forensics Analysis mechanisms should meet the following: - Short response times; User friendly interfaces l Questions addresses - How likely is a specific host relevant to the attack? What is the role the host played in the attack? How strong are two hosts connected to the attack? l Features of the prototype - Preprocessing mechanism to reduce redundancy in intrusion alerts - Graph model for presenting and interacting with th3 evidence - Hierarchical reasoning framework for automated inference of attack group identification

Example Prototype System: Modules l Evidence collection module l Evidence preprocessing module l Attack knowledge base l Assets knowledge base l Evidence graph generation module l Attack reasoning module l Analyst interface module

Summary l Network Forensics is the process of collecting and analyzing raw network data and then tracking network traffic to determine how an attack took place l Layered defense strategies to the network architecture l Live acquisitions are needed to retrieve volatile items l Standard procedure are needed to establish how to proceed after a network attack occurs l By monitoring network traffic can establish normal operations; then determine if there is an anomaly l Network tools used to monitor networks; but intruders can get admin rights to attack from the inside l Tools are available for monitoring network traffic for both Windows and Linux systems l Honeynet project enables people to learn latest intrusion techniques