Exam ● On May 15, at 10:30am in this room ● Two hour exam ● Open Notes ● Will mostly cover material since Exam 2 ● No, You may not take it early.

Intrusion Detection ● We have discussed the Security, “Life Cycle”  Maintain ● Keep your system secure and up to date  Detect ● Detect an attack  Recover ● Repair damage from attack and restore the system to working order.

Intrusion Detection ● We have spent a lot of time dealing with  Types of attacks  How to help secure systems against attack. ● We have spent some time on the issue of backups  The most simple and cost effective solution to restoration on your level ● We need to talk about the issue of Detecting attacks.

Intrusion Detection -- Baselining ● The most important concept in ID is baselining  We need to know what our system looks like ordinarily, so we can notice something extraordinary has happened ● We do this by making a record of the normal state of our system  Configuration files  Network Traffic  Data files...

Defenses ● Last week we divided our defenses into three groups  Network defenses – perimeter defenses  Host defenses  Data defenses

Defenses ● We will continue our discussion by talking about ways to detect breaches on these various levels

Network Defenses ● Network Defenses  Protect our LAN from attacks outside our LAN  Defenses are usually implemented by a boundary router or a personal router providing the following services ● Firewall ● NAT ● Possibly DHCP

Traffic Analysis ● We typically detect that an intruder has gotten into our local net by doing traffic analysis  We look at the kinds of packets on our net ● What protocols or applications generate them ● How heavy is the traffic on the network ● How much traffic does each host generate ● Anything else we can grab  We make a record of normal behavior, (baselining) and we look for unusual activity

Traffic Analysis ● Port scanning  Easy to detect, if carelessly done  Look for someone looking at a lot of ports on the same host. ● Increased Traffic  Hosts that have been taken over as zombies can generate greater than normal traffic

Traffic Analysis ● Looking for specific kinds of packets  Packets that carry worms can have a signature ● Similar to the signature of a file that has a virus  This signature can be detected  Sometimes, attack packets have header information that can be looked for. ● Any unusual activity  Could indicate an attack  Could simply indicate a hardware or software problem.

Host Defense ● Host Defenses can include  Anti Virus and anti Spam software  Personal firewall  Secure configurations or add ons to network software  Human Factors, (to be discussed later)

Host Defenses ● Again, we use baselining.  Contents of configuration files  Normal levels of CPU activity ● Hard to do  Normally running tasks and processes

Anti Virus Software ● Looks for “signatures” of viruses in executable files.  Alerts user if signatures found  This gives evidence of intrusion... at some point ● Anti Virus software can also help in recovery  Cleans infected files

Anti Spyware software ● Looks for a couple of things  Files associated with known threats  Tasks running that look like threats ● Out of the ordinary  Suspicious changes in configuration information ● In Windows, the registry ● In OS X, netinfo ● In Linux, state of configuration files

Anti Spyware Software ● Anti Spyware Software can contribute to recovery  Remove suspicious tasks, (stop them from executing)  Quarantine files  Remove or repair configuration changes ● Fix the registry

Other Approches ● Alert on  Attempts to write to the bios ● Often a parameter that can be set in the bios  Root Logins ● Fair or Foul, a root login is an important event  Attempts to write to system areas ● Areas where system programs are stored are usually only written to during upgrades or software installations. Writes at other times are suspicious.

Other Approach ● Alert on  Port Scans ● Again easy to detect

ID Host -- Tools ● Most Anti Virus Vendors provide total security packages that implement most of what I have discussed ● There are Freeware packages  Snort – Linux and Windows  Tripwire – used to be free, now nominal ● Most Unix Systems, including all Linuxes  Not much available for OS X ● Ports of some Unix packages

Data Defense ● Principle tool for defending data is encryption  Also detects modification of data  An encrypted file that is modified, can not be completely decrypted. ● We can also use baselining  Only on files that are relatively static

Baselining Data ● We can store, for static files.  Last modification date  Last access date  File size  A digital digest, or signature of the file. ● If any of these change, we know the file has been modified

Candidate files for Baselining ● Configuration files  Including Host files (redirecting to false websites)  Other network configuration files  Files related to the configuration of security software ● Executable files  Parts of the operating system  Frequently used executables

File Baselining ● Its tough to baseline files that are frequently changing  New baselines have to be computed for each modification  Modifier must authenticate himself/herself to the baselining software for each modification

Tools – File Monitoring ● Again about the same  Security packages from major vendors implement much of this  Tripwire and its replacements and descendants provide these services  Again, Mac OS X uses Unix tools

Recovery ● Critical Element of recovery is a plan  Reduces recovery time  Insures that needed materials are at hand ● Backups ● Replacement hardware  The process of planning exposes weaknesses

Backups ● As we have discussed, on your level, recovery, generally means restoring from backups  Unlikely to maintain duplicate equipment or file systems  Unlikely to employ a data warehouse

Recovery ● To restore usefulness to your system you must restore  Operating System ● OS cd/dvd and/or system restore disks  Application Programs ● Original installation disks ● Original installation files on removable media ● Web site addresses for downloading the programs

Recovery ● Critical Data  Documents ● Don't forget folders if stored locally  Bookmarks ● Often forgotten in backups. ● Use Export Bookmarks in favorite browser  Program configuration information  Personal Digital certificates ● Else you will get encrypted s you can't read

Recovery ● With a simple recovery plan like this you must budget hours or days to get back to full function ● However, it is cheap. ● If your need do not permit that much downtime you need to look for backup software and hardware that allows you to make complete disk or system images.