CIS-331: Introduction to Networks and Security

Fall 2019


Instructor: Sebastian Angel

Room: BENN 401

Time: Tu/Th 10:30 AM–12:00 PM

Email: sebastian.angel at

Discussion: Piazza

Office hours: Thursday 4 PM–6 PM (Levine 604)

Course Description

This course introduces principles and practices of computer and network security. It covers the following:


Even though NETS students are not required to take CIS 240, it is a prerequisite for this course. We will be enforcing these prerequisites.

Course Staff

Name Email (at Office hours (location)
Lawrence Dunn dunnla Tuesday 12:15–2:15 PM (GRW 5th floor bump space)
Natasha Gedeon nged Wednesday 12:30–2:30 PM (GRW 5th floor bump space)
Amit Lohe alohe Wednesday 4–6 PM (Levine 6th floor bump space)
Michael Zhou mizho Friday 12:30 PM–2:30 PM (Levine 5th floor bump space)


There is no required textbook for this course. The following three books (available for free) are good extra sources:

Assignments and exams

There will be 4 homework assignments to be completed individually, and 4 projects to be done in pairs. There are two exams: a midterm and a final.

Late Days. You will have a budget of five late days (24-hour periods) over the course of the semester that you may use to turn assignments in late without penalty and without needing to ask for an extension. Late pair projects will be charged to both partners. Once your late days are used up, extensions will only be granted in extraordinary circumstances. Late days can be used for homeworks and projects, but not exams. To use a late day, just turn in your assignment late. There is no need to notify the course staff. If you have an extenuating circumstance, you must contact the course staff before the assignment is due.


Academic Honesty

We encourage you to discuss the problems and your general approach with other students in the class. However, the answers you turn in must be your own original work, and you must adhere to Penn’s Code of Academic Integrity.

For more information, see the Office of Student Conduct.

Students with disabilities

The University of Pennsylvania provides reasonable accommodations to students with disabilities who have self-identified and received approval from the Office of Student Disabilities Services (SDS). If SDS has approved your request for accommodations, please make an appointment to meet with me as soon as possible in order to discuss the arrangements for your accommodations. SDS services are free and confidential.

Belonging, inclusion, and wellness

The CIS department and all of the faculty and staff are committed to making your studies here at Penn a safe and rewarding experience. This can only happen if we work together to create an inclusive environment that welcomes all students, regardless of their race, ethnicity, gender identity, sexuality, or socioeconomic status. Diversity, inclusion, and belonging are all core values of this course. All participants in this course deserve, and should expect, to be treated with respect by other members of the community. We encourage all students to visit the CIS Diversity site to learn about all avaialble resources.

A sense of belonging can also affect students’ mental health and wellness, which is of utmost importance to the course instruction staff, if not the University as a whole. All members of the instruction staff will be happy to chat or just to listen if you need someone to talk to, even if it’s not specifically about this course.

If you or someone you know is in distress and urgently needs to speak with someone, please do not hesitate to contact CAPS: 215-898-7021; 3624 Market St. If you are uncomfortable reaching out to CAPS, any member of the instruction staff will be happy to contact them on your behalf.

Tentative Schedule

Date Topic Reading


course overview, threat models, defensive programming

The Security Mindset by B. Schneier

How to think like a security professional by T. Kohno

This World of Ours by J. Mickens


Project 1 out

Control hijacking

buffer and integer overflow, stack smashing, format string vulnerability

Memory Safety Attacks and Defenses by D. Wagner

Smashing the stack for fun and profit by Aleph One

errata for "Smashing the stack for fun and profit" by M. Walfish

(optional) Low-level Software Security by Example by U. Erlingsson, Y. Younan, and F. Piessens

(optional) Basic Integer Overflows by blexim


Homework 1 out

Control hijacking defenses

stack canaries, NX bit, ASLR

Buffer Overflows: Attacks and Defenses by C. Cowan, P. Wagle, C. Pu, S. Beattie, and J. Walpole

Smashing the stack in 2011 by P. Makowski


Return-oriented programming

bypassing NX and ASLR

Return-to-libc attacks by c0ntex

(optional) Return-Oriented Programming: Systems, Languages, and Applications by Roemer et al.

(optional) Introduction to return-oriented programming by A. Reece


Homework 1 due

OS security

privilege separation, isolation, setuid, chroot

Principles for Building Secure Systems by D. Wagner

Design Patterns for Building Secure Systems by D. Wagner

The Confused Deputy by N. Hardy



Password attacks, usability, hygiene, alternatives

The Tangled Web of Password Reuse by Das et al.


Cryptography introduction

confidentiality, adversaries, classic ciphers

Historical ciphers by N. Smart

Introduction to cryptography by B. Barak (Chapter 1.1–1.3)


Project 1 due

Homework 2 out

Classic ciphers and symmetric encryption I

Vigenere cipher, one-time pad, perfect secrecy

Information-theoretic security by N. Smart


Symmetric encryption II

stream ciphers, PRGs, unpredictability

Historical stream ciphers by N. Smart

Pseudorandomness by B. Barak


Project 2 out

Symmetric encryption III

statistical tests, indistinguishability, negligible functions, semantic security

Negligible functions by D. Boneh and V. Shoup

Computational security by B. Barak


Homework 2 due

Symmetric encryption IV and Hash functions

block ciphers, PRPs, Merkle-Damgard construction

Block ciphers by N. Smart

Hash functions by N. Smart.

(optional) Hash functions and Bitcoin by B. Barak.


MACs and authenticated encryption

length extension attacks, PRFs, ciphertext integrity

Pseudorandom Functions by M. Bellare and P. Rogaway

Message authenticated Codes by N. Smart.


Public Key Encryption I

Diffie-Hellman key exchange, trapdoor functions, public key encryption from trapdoor functions

Asymmetric Encryption by D. Wagner

Public Key Tools by D. Boneh and V. Shoup

10/10 Fall break


Public key Encryption II

RSA trapdoor permutation, RSA-KEM, RSA-OAEP, RSA digital signatures, RSA-FDH, PKCS#1 v1.5

Public key encryption by D. Boneh and V. Shoup

MACs and Digital Signatures by R. Popa and D. Wagner


Project 2 due

Homework 3 out


Certificates, PKI, TLS handshake, forward secrecy

TLS 1.2 (RFC 5246)

TLS 1.3 (RFC 8446)

Everything you Never Wanted to Know about PKI but were Forced to Find Out by P. Gutmann

10/22 Midterm Exam Includes content up to Public Key Encryption I (10/8)


Project 3 out

Web overview

threat model, HTTP, HTML, JavaScript

Web technology for developers by Mozilla


Web Attacks I (Guest lecture)

Same origin policy, cookies, SQL injection

Secure Session Management With Cookies for Web Applications by Chris Palmer

SQL injection prevention cheat sheet by OWASP


Web attacks II


Cross-Site request forgery prevention cheat sheet by OWASP

Cross-site scripting prevention cheat sheet by OWASP


Homework 3 due

Networking I


Security problems in the TCP/IP protocol suite by S. Bellovin

What is BGP by Cloudflare


Networking II

Ethernet, ARP, DHCP, NAT


Project 3 due

Project 4 out

Denial of service (Guest lecture)

DOS, DDOS, SYN flooding, client puzzles

An analysis of China's "Great Cannon" by Marczak et al.


Network attacks and defenses

DNS poisoning, BGP hijacking

DNS security threats and mitigations by Google

A Study of Prefix Hijacking and Interception in the Internet by H. Ballani, P. Francis, and X. Zhang


Homework 4 out


End-to-end encrypted email, VPN, Private browsing

Deep dive on End-to-End encryption by the EFF

An Analysis of Private Browsing Modes in Modern Browsers by Aggarwal et al.



The great firewall of China, decoy routing, domain fronting

The Great Firewall Revealed by Global Internet Freedom Consortium.

Decoy Routing by Karlin et al.

Blocking-resistant communication through domain fronting by Fifield et al.

11/26 Thanksgiving break
11/28 Thanksgiving break


Homework 4 due



Tor: The Second-Generation Onion Router by R. Dingledine, N. Matthewson, and P. Syverson.


Underground economy

Spam, phishing, botnets


Project 4 due
12/12 Final Exam: 9 AM–11 AM (Location: STIT B6)


Many of this course's materials have been adapted from J. Alex Halderman, and all materials are available under a Creative Commons License.