Foundations of Network and Foundations of Network and Computer - - PowerPoint PPT Presentation

Foundations of Network and Foundations of Network and Computer Security Computer Security

J John Black

Lecture #14 Oct 18th 2005

CSCI 6268/TLEN 5831, Fall 2005

Announcements

• Quiz #2 back today

– We’ll go over some points before we start the lecture

• Project #0 due today

– Please hand in on paper – CAETE students can email to grader: Martin.Cochran@colorado.edu

Password Protected Private Key

• Shouldn’t leave your private key lying around

without password protection; let’s fix this

% openssl genrsa -aes128 -out john-priv.pem 1024 Generating RSA private key, 1024 bit long modulus ...........................................++++++ ..........................++++++ e is 65537 (0x10001) Enter pass phrase for john-priv.pem: Verifying - Enter pass phrase for john-priv.pem: % openssl rsa -in john-priv.pem -text -noout Enter pass phrase for john-priv.pem: Private-Key: (1024 bit) modulus: 00:ca:40:b9:ef:31:c2:84:73:ab:ef:e2:6d:07:17... ...

What does key look like now?

• ----BEGIN RSA PRIVATE KEY-----

Proc-Type: 4,ENCRYPTED DEK-Info: AES-128-CBC,1210A20F8F950B78E710B75AC837599B fFbkGjYxpp9dEpiq5p61Q/Dm/Vz5X2Kpp2+11qFCKXLzxc8Z8zL7Xgi3oV5RUtSl wFjkiJaPP7fyo/X/Swz0LO1QKVQ7RDUe9NpnwTUBV44rtQVsSWfbgzdA9MAQT945 wBI27OAJWYQTApEeM2JhgvqCSPtdIn9paC9yeIzXLxwqrnlLCscGKncX53y3J3QG KP1UqujpdTY9FRMvbL6bM5cn1bQ16pSbjntgFi5q4sdcwBNiWveFy5BNf4FnWtk6 KdAQ4jFeZqnwR3eAP0kdleosucPNZMxoQKafsi19bGi9BDdR4FoBdHy+K1sbXEm0 Z5+mcVPIITmB9MgUQLZ/AFguXHsxGDiH74es2Ahe6OACxWlqe4nfFxikXJfJw8EY 9nzw8xSZV5ov66BuT6e/K5cyrd2r0mlUb9gooYoVZ9UoCfO/C6mJcs7i7MWRNakv tC1Ukt9FqVF14Bcr1oB4QEeK1oWW3QU2TArCWQKc67sVcSBuvMJjBd18Q+8AZ7GY Jtt4rcOEb0/EUJuMauv4XlAQkiJcQ46qQjtkUo346+XMeRjWuUyQ/e5A/3Fhprat 7C10relDQonVi5WoXrEUTKeoaJgggZaeFhdpoee6DQePSWfLKB06u7qpJ6Gr5XAd NnBoHEWBYH4C0YcGm77OmX7CbPaZiIrha/WU7mHUBXPUHDCOhyYQK8uisADKfmEV XEzyl3iK6hF3cJFDZJ5BBmI774AoBsB/vahLquBUjSPtDruic24h6n2ZXcGCLiyc redr8OiGRJ0r6XF85GYKUO82vQ6TbSXqBgM5Llotf53gDZjMdT71eMxI4Fj3PH91

• ----END RSA PRIVATE KEY-----

This private key file is encrypted

CSR: Certificate Request

• You will generate a CSR

– Certificate Request

• Has your name, email, other info, your public key, and you

sign it

• Send your CSR to the CA

– CA will sign it if it is properly formatted – His signature overwrites your signature on the CSR

• Once CA signs your CSR it becomes a

certificate

Creating a CSR

% openssl req -key john-priv.pem -new -out john-req.pem Enter pass phrase for john-priv.pem: You are about to be asked to enter information that will be incorporated into your certificate request. Country Name (2 letter code) [AU]:US State or Province Name (full name) [Some-State]:Colorado Locality Name (eg, city) []:Boulder Organization Name (eg, company) [Internet Widgits Pty Ltd]:University of Colorado Organizational Unit Name (eg, section) []:Computer Science Common Name (eg, YOUR name) []:John Black Email Address []:jrblack@cs.colorado.edu (Leave the rest blank) This outputs the file john-req.pem which is a cert request

Viewing a CSR

% openssl req -in john-req.pem -text -noout Certificate Request: Data: Version: 0 (0x0) Subject: C=US, ST=Colorado, L=Boulder, O=University of Colorado, OU=Computer Science, CN=John Black/emailAddress=jrblack@cs.colorado.edu Subject Public Key Info: Public Key Algorithm: rsaEncryption RSA Public Key: (1024 bit) Modulus (1024 bit): 00:ca:40:b9:ef:31:c2:84:73:ab:ef:e2:6d:07:17: 83:5e:96:46:24:25:38:ed:7a:60:54:58:e6:f4:7b: ... 27:de:00:09:40:0c:5e:80:17 Exponent: 65537 (0x10001) Attributes: a0:00 Signature Algorithm: md5WithRSAEncryption 32:e1:3f:e2:12:47:74:88:a3:f9:f4:44:8a:f3:b7:4e:d1:14: 1f:0b:be:b8:19:be:45:40:ed:5b:fb:ab:9b:01:e8:9a:26:0c: ... 9c:e0

CSR is signed by you Note: not password protected

CSRs

• Why is your CSR signed by you?

– Ensures that the CSR author (you) have the private key corresponding to the public key in the CSR

• If we didn’t do this, I could get the CA to sign anyone’s public

key as my own

– Not that big a deal since I can’t decrypt things without the corresponding private key, but still we disallow this

• Why does the CA sign your public key

– Well, because that’s his reason for existence, as discussed previously – Ok, let’s say I email my CSR to Martin and he signs it… then what?

Sample Certificate

• ----BEGIN CERTIFICATE-----

MIIDkDCCAnigAwIBAgIBCzANBgkqhkiG9w0BAQQFADCBgTEQMA4GA1UEAxMHSm9o biBDQTERMA8GA1UECBMIQ29sb3JhZG8xCzAJBgNVBAYTAlVTMSYwJAYJKoZIhvcN AQkBFhdqcmJsYWNrQGNzLmNvbG9yYWRvLmVkdTElMCMGA1UEChMcUm9vdCBDZXJ0 aWZpY2F0aW9uIEF1dGhvcml0eTAeFw0wMzExMTMyMDQ1MjFaFw0wNDExMTIyMDQ1 MjFaMIGFMRIwEAYDVQQDEwlUZXN0IFVzZXIxETAPBgNVBAgTCENvbG9yYWRvMQsw CQYDVQQGEwJVUzEjMCEGCSqGSIb3DQEJARYUdGVzdEBjcy5jb2xvcmFkby5lZHUx FjAUBgNVBAoTDVVuaXYgQ29sb3JhZG8xEjAQBgNVBAsTCUNTQ0kgNDgzMDCCASIw DQYJKoZIhvcNAQEBBQADggEPADCCAQoCggEBAL1k6hJ9gwXlUYHiFOm6OHOf+8Y0

• 1b7WOexYfNDWm9H0I79o0wVgDj7waOgt4hz2FE2h+gArfGY5VsaSzmCH0EA4kDS

m/sPob3HTVpbIFwlbXTV7hC0OxOzRs8lphDdj1vaNDSnOwqOS1ADCfIdaGEh9WKi rEdFdriiu7v1bw+c1ByM57v9aHO7RslswR9EnRFZPWYa8GpK+St0s8bZVf98IOOk H8HiliyVSt5lAXRMnIxhYMG89tkkuCAwxgDD+7WqyETYxY0UCg/joFV4IKcC7W1b CmvxsY6/H35UpGgv0anCkjyP0mKY/YWB9KXwrR8NHC7/hacij0YNiV77EIMCAwEA AaMNMAswCQYDVR0TBAIwADANBgkqhkiG9w0BAQQFAAOCAQEAZr4hdQPcGnAYmk++ 0bQ4UKILXj9wr7UZdgz3DKJNpMPkFjzU6wvJrd1C8KIKfJC63TKHJ7svmdZwTCB2 hNUFy8kbe2KvNWQiGoX3PaY1eo3auLzIi8IxPqN+W/p1z3MhtpQqNllqzG8G1o50 QP2yAyj2V0rnwlRL3kZ7ibvXRnSB1Bz+6zJJLAQr4kTQD2EfxLhpks+iSE+m58PV tfck25o2IMJYYLAdtoNGjcFG9/aDk+GHbsx8LP/va6B6BIzB3vrefuQvBu+7j/mz aXP7QkuGYf1r4yyOiuMYnw0kwp5xndDKTzORsxksHQk5AWfBXrDdGPZrb6i1UlOq U/P3+A==

• ----END CERTIFICATE-----

Ooh…how useful!

Viewing a Certificate

% openssl x509 -in john-cert.pem -text –noout Certificate: Data: Version: 3 (0x2) Serial Number: 1 (0x1) Signature Algorithm: sha1WithRSAEncryption Issuer: CN=Martin Cochran, ST=Colorado, C=US/emailAddress=Martin.Cochran @colorado.edu, O=University of Colorado Validity Not Before: Oct 17 19:52:43 2005 GMT Not After : Oct 17 19:52:43 2006 GMT Subject: C=US, ST=Colorado, L=Boulder, O=University of Colorado, OU=Computer Science, CN=John Black/emailAddress=jrblack@cs.colorado.edu Subject Public Key Info: Public Key Algorithm: rsaEncryption RSA Public Key: (1024 bit) Modulus (1024 bit): 00:ca:40:b9:ef:31:c2:84:73:ab:ef:e2:6d:07:17: 83:5e:96:46:24:25:38:ed:7a:60:54:58:e6:f4:7b:. . . 27:de:00:09:40:0c:5e:80:17 Exponent: 65537 (0x10001) Signature Algorithm: sha1WithRSAEncryption 97:4a:20:ea:a7:5a:4d:4c:77:b9:3e:c0:49:9b:ab:8f:6f:02: 53:24:a9:71:97:2c:1f:e8:e4:eb:d0:f6:6a:7c:74:30:1d:9e: . . . 3a:59

Again, no encryption Now it’s the CA’s signature

What have we Accomplished?

• We have an X.509 cert

– It contains our public key, name, email, and other stuff – It is signed by the CA

• You have a private key in a password-protected

file

– Don’t lose this file or forget the password!

• What else do we need?

– We need to be able to verify the CA’s signature on a public key! – We therefore need the CA’s verification key

CA’s Verification Key is a Cert!

• The CA generates a self-signed “root

certificate”

– This is his verification key (aka public key) which he signs – This certificate is what is embedded in your browser – This certificate is used to validate public keys sent from other sources – Martin’s root certificate will be used to validate all public keys for our class

Martin’s Root Cert

• ----BEGIN CERTIFICATE-----

MIIDoTCCAomgAwIBAgIJALqpKIgpakS2MA0GCSqGSIb3DQEBBQUAMIGGMRcwFQYD VQQDEw5NYXJ0aW4gQ29jaHJhbjERMA8GA1UECBMIQ29sb3JhZG8xCzAJBgNVBAYT AlVTMSowKAYJKoZIhvcNAQkBFhtNYXJ0aW4uQ29jaHJhbkBjb2xvcmFkby5lZHUx HzAdBgNVBAoTFlVuaXZlcnNpdHkgb2YgQ29sb3JhZG8wHhcNMDUxMDE3MTk1MjQz WhcNMDYxMDE3MTk1MjQzWjCBhjEXMBUGA1UEAxMOTWFydGluIENvY2hyYW4xETAP BgNVBAgTCENvbG9yYWRvMQswCQYDVQQGEwJVUzEqMCgGCSqGSIb3DQEJARYbTWFy dGluLkNvY2hyYW5AY29sb3JhZG8uZWR1MR8wHQYDVQQKExZVbml2ZXJzaXR5IG9m IENvbG9yYWRvMIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAxR40jv85 z6AckjvP9yuTDYS7tbCiai738aHpGVGXviUfdPR2TS3laRxXnh8Nd8i4LT8+X/BB WJk9leBs82VfuEEO2m7ksriHu+Z1vADJ0q9L6cmxHQkPA32okxOPlx33F6uU+E7+ qfvO1Uimf/QAbWvXTHlnv/BtIvz2hRHiUguuNxIqVqFpejebL7qerzqIBei6oBTo OMkj7sjxXM6/agU7p1xAxlnxuslPKw9ff8QR7N4AiFrGmQkaFpjdZGTdFyofmXRB MBahb4Zn1/DvWA1tHFJGAv2EEEMd5eyURzbt+kd2XjtHdyHd62Rf8bZ6YzPinI3o 72+goFpWW97YEwIDAQABoxAwDjAMBgNVHRMEBTADAQH/MA0GCSqGSIb3DQEBBQUA A4IBAQAk15usr3Y9fWKdmFzRjyl7ICvXLb3bApBEA4RFIHv6iMAPtL58XgYo48ke EhCxt4YJU2edOql2Ko+lGq9DnDM12aLfpGTxF6+QzgBC0cA3BewxvueWTWQF23V6 bnVeQqZmK3m+bv4rvj0x1HMKSVqfS83UDJxv8kFq1EQj2jaWOVuuIDLGNBr75xTk /LbzDyY/BLmrBtsdG1VCAm6ONLRfSEumQ2B3fWpa8ElcvKNTR6WJOeHIhK0VUHRW 14bxvMNWSgQEPSqbeSUrHM7arZMbvE7/CFPxn/Sjvgz9Pkjm0fJh4AIKzTq/7K2Z xZK7ZGq0UP6nMS75a7Hy/qOC1YQe

• ----END CERTIFICATE-----

How to Distribute the Root Cert?

• It’s ridiculous for me to ask you to write

this down, right?

– If I email it to you, it might get altered by an adversary – If I put it on the web page, it might get altered by an adversary – Ok, this is probably not a REAL concern for us, but we’re practicing being paranoid – What can we do?

Distributing the Root Cert

• Fingerprint the root certificate!

– We’ll just distribute the fingerprint as a verification check – The cert itself will be distributed via some insecure means – The fingerprint will use a collision-resistant hash function, so it cannot be altered – But now we have to distribute the fingerprint

• This you can write down, or I can hand you a hardcopy on a

business card, etc

• People used to have a fingerprint of their PGP public key on

their business cards at conferences… haven’t seen this in a while though

Root Cert Fingerprint

% openssl x509 -in cacert.pem -fingerprint -noout MD5 Fingerprint =

94:F7:2F:8A:2C:1D:71:EC:7C: 6A:C6:60:27:5C:3B:CF

• Please write this down now
• And, yes, some is going to point out that perhaps my powerpoint

was infiltrated during the night, so I’ll check against my hardcopy

Overall Idea of the Project

• Each student has a cert containing a public key corresponding to his

private key

• Each student knows the verification key of the CA
• Student A wants to send secure mail message M to student B

– A obtains B’s cert and verifies it is correctly signed by the CA – A chooses a random session key K and RSA encrypts using B’s public key (from B’s cert) – A writes out the encrypted K followed by M encrypted symmetrically, then signs each of these with her private key and sends to B

• B receives all of this and…

– Obtains A’s cert and verifies it is signed by CA – B verifies A’s signature on the message – B uses his private key to decrypt K (session key used by A) – B uses K to decrypt M

Sample Message from A to B

• ----BEGIN CSCI 6268 MESSAGE-----

hjh2vkeSGpWehAwgMOEbKomsW3lTd8BBBrEfFchbAZpnbc+O7wcI8OT0g9WP9iPV K92xbzAiVlAN7ZFOWlx/iX2XQIbUQBU6kl7NOyPTtSZ/5+9JHVDY1TFZG3cGtVj5 SeJ97+kvuWkZvNcKjAec1YbRYpXRGwRmqPtz+o5WYWqWmqPV6lQWjbN4Jc+w2Gcl FKR7t0Zsi5RcnEwIn+cZtuTe3QWW4/inMGMBFgbXjA2E6VU7zn62BdBHh7S1/oBR tt84Rr4/oXXJhrEASdZJEdGw8trh0FPd48ioHElT7TNGMx4YJKHBV1+EMjTcHwdN DCr29AZ2QyDh/pHYqvJmVg== U2FsdGVkX1/QUjgfw4jEV34P/Efn8Ub7NDzV5QL+uWoeDblspQiz2BiPqQEa1acb CD2+XgD36FmmcP9WxDOdQ63AlX2K4t4SdSyTT8uk9YpdUC0thqCXFkDGM6P0u7Xx gBxP0s0mtcNFKbcpwmiEp5K8ayGHsYW5lM2veFclVL75xReQGA8fkjZ3OQQeR+nz nQTg2Hniyaniwbb11YgBmyWQ4bsVK5UDG0iYab100cvPUlFZXrMmK4aumMNtC+0Z +Syj4FaPzUphhebhuhsU29tahd8hL9DZQ5ZuzZiZi5hy0nG5z45FHktap/bwwOGC Iu3mRM6ZqoTVVanTqf0cBaRA5c+XJbhuXLxjS44viFKSKENmZ7pEPZtdisvd/aq2 weZb1amCy2jnP0xQioI8Lc/zkno5XRW21bGH3kWeG8kMuOrBKVyms2FOEpsI0TH0 UIzck095R4jnPUI+e7S85z1Wx1ToyMI3Ub/Mee3MyIt60H2r2LC4sp9CO1Yn4tYN pA4ULy3DhFy4z9x4bX+aU+bSymiqf5JvSjMXS/zQYERW+1fhOKnU3fI518mE9Gbx tJBJJmjnPxWhWpSJjvG7qEAdy/PibcD8YPXn3NZ7j1mU8SgYog9vwJwz3fsKaCS6 AP4LTLN9ef5Hb/STtvA+ow==

• ----END CSCI 6268 MESSAGE-----

RSA Encrypted Session Key K AES-128-CBC encrypted message M RSA signature on first two chunks

The Big (Partial) Picture

Primitives

Block Ciphers Hash Functions Hard Problems Stream Ciphers

First-Level Protocols

Symmetric Encryption Digital Signatures MAC Schemes Asymmetric Encryption

Second-Level Protocols

SSH, SSL/TLS, IPSec Electronic Cash, Electronic Voting

(Can do proofs) (Can do proofs) (No one knows how to prove security; make assumptions)

Network Security

• Haven’t we already been talking about

network security?!

– Kind of… cryptography is a central part of it – Cryptography is nice because it’s a neatly packaged science; but we’re done for now – Network security itself is a vast area with fuzzy borders – Research tends to be more ad hoc

• How do we stop attack A, how do we prevent bug

B, how do we detect or tolerate intrusions, etc.

Crypto …. Good

• The easiest way to break into a computer

is usually not by breaking the crypto

– We’ve said this a number of times in this class before; there are usually easier ways

• Let’s suppose we want to break into a

friend’s account on CSEL

– What kind of friend are you?? – Ok, give me methods… simple methods

Breaking into a “Friend’s” Account

• Digression

– Before we talk about this, let me introduce the “John Disclaimer” – I would like each of you to sign a statement “promising not to be evil” – I will hand this out at the end of lecture

• Please remind me

– It’s also on our web site…

• Distance students, please print this out and send it

in

Ok, Breaking into a “Friend’s” Acct

• Fake Login Screen
• Shoulder Surfing
• Password Cracker

– MD5 hashes publicly available on web

• Social engineering

– Hard to trick CSOps though – Might be easy to impersonate CSOps! ☺

• Key loggers

– Software and hardware versions

• Keystroke analysis

– Ok, getting obscure

Networking Refresher

• For some of you this will be boring… sorry
• The basic model:

ISP ISP Backbone (not a single line these days) LAN LAN Eth Eth user1 user2

Basic Networking

• Suppose user1 sends a UDP packet to user2,

what happens?

– What’s UDP?

• User Datagram Protocol
• Just like IP but with ports

– Well, first we need an IP address!

• What’s an IP address
• For IPv4, it’s a “dotted quad” of bytes

– Ex, 128.138.242.21 – 32 bits

• For IPv6, it’s 128 bits

– 16 bytes in hex separated by colons

Running out of IP addresses

• 232 is a lot, but we’re having problems

– A lot of hosts out there – The class A, B, C scheme is wasteful

• Though subnetting helps
• A lot of NAT Boxing “helps”
• Since we’re getting by, it means a slower migration

to IPv6

Sending a UDP packet

• Assume IPv4

– Get IP address via DNS

• Domain Name Service
• Distributed database mapping textual names to IP

addresses

• Insecure

– DNS spoofing – More on this later

– Ok, so we have an IP address – And we presumably have a port #

Pack it Up!

Message UDP Header Src IP, Dest IP, Len, Chksm, TTL Src Port, Dest Port, Len, Chksm Eth Header IP Header Src addr, Dest addr, Chksm Ethernet addresses are called “MAC addresses” Ethernet checksum is actually appended to end of packet Ethernet MTU is 1500 bytes

Routing on a Network

• Usually done via OSPF or LSP for LANs

– Open Shortest Path First, Link-State Protocol – These protocols assume “modest sized” networks – A routing protocol decides how to forward packets based on routing tables

• BGP is used on backbone

– Border Gateway Protocol – Routes using incomplete information

Local Routing Table

• Our local routing table (on host of user1) is

not going to have a route to IP of user2

– Routing table will therefore send our packet to the gateway – Gateway is the machine/router on the “edge”

• f the network responsible for processing all

incoming/outgoing traffic from/to the LAN

• NAT boxing, firewalling, and other stuff is usually

done here as well

Getting to the Gateway

• How to we route to the IP address of the

gateway on our local Ethernet?

– ARP (Address Resolution Protocol)

• Translates IP addresses into MAC addresses
• Caches old lookups, so we probably already have the MAC

address of the gateway

• If not, we send an ARP Request to the LAN, including the IP

address whose MAC we seek

• Owner (ie, the gateway) sends ARP Reply with his MAC

address and we cache it

– Usually, all other machines who hear the ARP Reply cache it as well – Leads to attacks… more later

Sending to the Gateway

• Now we have the MAC address of the gateway

– Send our packet to the gateway via the Ethernet protocol – This is usually done with a hardware device (network card) which often puts the Eth header on your packet for you, computes checksums, etc.

• Broadcasts packet, detects collisions
• Exponential backoff
• Promiscuous mode – Sniffers use this

– Works through hubs, but doesn’t work through switches on a switched Ethernet – You can often fool switches

Gateway Receives Eth Packet

• Strips Eth header and again tries to route

the resulting IP packet

– Looks in routing table, sends to ISP – ISP probably routes using BGP – Reaches other ISP

• Note that we’re using other Ethernets and similar

physical-layer protocols for each hop!

– Other ISP routes to other LAN’s gateway

• Gateway sees IP is in its range and does ARP to

route to user2

User2 Receives Packet

• User2 receives the IP packet

– Removes IP header

• No one else (is supposed to) look inside packet

until user2 receives it

• NAT boxes break this rule
• Firewalls break this rule

– See it’s a UDP packet and “sends” to proper port – Ports are mapped to applications via listento()

• Application receives message and processes it

Other Protocols

• We didn’t even talk about SLIP or PPP
• ATM, FDDI, Wireless
• What about DHCP?

– Dynamic IP addresses

• There is also ICMP

– Internet Control Message Protocol – Echo (ping), traceroute

• Application Layer Protocols

– SNMP – Network Management – SMTP – Sendmail – POP/IMAP – Mail protocols

MTU – Maximum Transmission Unit

• MTU for Ethernet is 1500 bytes

– If MTU is exceeded, packet is “fragmented” – IP has support for packet fragmentation and reassembly – A packet is broken into as many pieces as necessary to comply with MTU – Fragments routed as regular IP datagrams, independent of each other – Reassembly done at host only

IP – Best Effort Datagrams

• IP is “best effort”

– There is no tracking of packets – If something is dropped… oh well – If one fragment is dropped, many transport layer protocols (like TCP) will consider the whole thing lost and not ACK – This seems bad, but it’s one of the biggest successes of IP – UDP is IP with ports, so it too is “best effort”

TCP – Transmission Control Protocol

• Stateful connections

– Runs over IP just like UDP, but adds more than just ports – Establish a connection with listen() and connect()

• IP and UDP were “stateless” protocols

– Reliable delivery

• Unlike best-effort, this protocol guarantees delivery of

packets, in proper order

• Uses sequence numbers, sliding windows, ACKs every

transmission

Crypto on a Network

• How do we do crypto on a network?

– We’ve seen application-layer examples

• SSL/TLS, SSH
• This is called “end-to-end” cryptography, meaning between

hosts

• The routers don’t care if the innermost part of each packet

(the “payload”) is ciphertext or plaintext

– IPSec

• IPSec does crypto at the network layer (the IP layer)
• Extremely well-engineered; hardly used
• We won’t study IPSec in this course

Network Security: The Biggest Challenges

• What are the biggest problems now, today, on

the Internet

– What are the most common types of attacks?

• Viruses, worms
• Break-ins via software vulnerabilities
• Denial of Service attacks (DoS)

– And Distributes Denial of Service (DDoS)

– What about keyloggers, spyware, rootkits?

• Not as relevant to network security
• More likely to be end-results of other break-ins

– A recent virus was found to install a keylogger

Viruses (Worms)

• Today, most everyone just calls them

viruses

– Technically most are “worms” – Worm is a self-contained propagating program – Viruses embed in other programs and self- replicate

• Kind of like viruses in biology

Viruses: History

• Morris Worm, Nov 2nd, 1988

– The first worm (I know of) was the Morris worm – Robert T. Morris, Jr.

• 23 years old
• Cornell grad student
• Father worked at the NSA (whoops!)

– Wrote a self-propagating program as a “test concept”

• Exploited Unix vulnerabilities in sendmail and fingerd
• Released at MIT
• Bug in the worm caused it to go wild

– Probably wouldn’t have caused much damage otherwise!

Morris Worm (cont)

• Shut down thousands of Unix hosts

– But this was 1988…

• Reactions

– People didn’t know what to do, so they panicked

• Disconnected from net
• Unable to receive patches!

– Morris fined $10k, 3 yrs probation, 400 hrs community service – CERT was created

CERT -- They were first

• Carnegie mellon Ermergency Response Team

– But don’t expand it into an acronym

• Provide technical advice and coordinate

responses to security compromises

• Identify trends in intruder activity
• Work with other security experts to identify

solutions to security problems

• Disseminate information to the broad community
• Analyze product vulnerabilities
• Publishes technical documents
• Presents training courses

Modern Viruses

• Almost all look for Windows hosts

– Windows runs on more than 90% of desktops these days – A lot of hosts on cable modems

• Fast, always on

– Destructive payloads

• Wipe hard disk, eg
• Some install backdoors for later use

– All kinds of weird behaviors though

• Some innocuous

Viruses: Why?

• Who writes these things?

– Typical profile: male, teenager, geeky, smart – Script Kiddies

• Don’t really write them, but launch them
• Sometimes make small mods and call them their own
• Scariest hackers: beyond the reach of the law
• Why?

– Intellectual challenge (sigh…) – Peer recognition – Bot building (Zombie armies) – Because it’s there?