Introduction to Information Security Wireshark and Scapy

Exercise 6 Submission deadline extended to 3.5 to fix the following issues: Check the exit code only to determine whether convert failed Put the explanation as to why fuzzing the first and last 750 is enough at the top of the .txt file Use the correct format 0x<byte>.<bit>\n Bits are numbered from 0 to 7 Bytes are numbered from 1 Don't copy the entire file over for every bit flip, that's ridiculously inefficient

The Great Ascent We shift our focus from low-level vulnerabilities (buffer overflows) to high-level ones (DNS poisoning) Network vulnerabilities are just as sophisticated and interesting! They are not simpler, but they are easier to debug Tools: Wireshark (and maybe tcpdump) Scapy

A Few Words about Python

Python Probably the best language in the world For scripts, we know... But also: For web development (django, flask) For scientific research (numpy, scipy, sympy, matplotlib, ipython notebook) For big data analysis (pandas) For machine learning (scikit.learn) For big and complex systems (twisted, sqlalchemy) Other stuff (re, pycrypto, PIL, nltk, scrapy)

A Few Words About Python How can it be? It's modern and cool It's extremely dynamic Everything is an object (even classes!) You can overload and hook just about anything Focuses on developer time Simplicity Interactivity As a side-note for skeptics, with stuff like PyPy it's also incredibly fast Nowadays, that's what takes 90% of the time!

Example class A(object): def __call__(self, x, y): return x + y def __getitem__(self, key): return key.upper() def __getattr__(self, key): return key.ljust(10, '.') >>> a = A() >>> a(1, 2) 3 >>> a['foo'] 'FOO' >>> a.foo 'foo.......'

How to Learn If you're not sure how to do something, Google it or look in Stack Overflow Don't copy solutions blindly – but do learn from them For example, many of you reinvented the wheel instead of using binascii / struct Almost nobody automated the core dump address extraction  Sounds hard?

Example

Back to the Point

Wireshark Allows to capture ("sniff") incoming and outgoing packets Amazing deconstruction and visualisation Incredible number of supported protocols Filters and more

Wireshark

Scapy A Python library that allows constructing, deconstructing, sending, receiving, sniffing and virtually doing anything you can imagine with packets Read the tutorial: http://www.secdev.org/projects/scapy/doc/usage.html >>> from scapy.all import * >>> s = IP(dst='212.179.180.89') / TCP(sport=65000, dport=80, flags='S') >>> a = sr1(s) >>> a[TCP].sport 80 >>> a[TCP].sprintf('%TCP.flags%') 'SA' >>> sniff(lfilter=lambda p: UDP in p, prn=lambda p: p.summary()) ...

Exercise 7 A series of unrelated question, each about a problem and its solutions The problems themselves may have been learned in class But anyway, they are explained in detail and are in fact quite simple A big open bonus I will personally grade "by ear" (so no appeals – but do try to impress me)