Soma-notes - User contributions [en]

SystemsSec 2016W Lecture 22

2016-04-05T18:24:07Z

Hammadasad: /* */

==Topics and Readings==
*Cookies And Integrity
**Xiaofeng Zheng et al., ''[https://www.usenix.org/conference/usenixsecurity15/technical-sessions/presentation/zheng Cookies Lack Integrity: Real-World Implications]'' (USENIX Security 2015)
*JavaScript Injection
**Sebastian Lekies et al., ''[https://www.usenix.org/conference/usenixsecurity15/technical-sessions/presentation/lekies The Unexpected Dangers of Dynamic JavaScript]'' (USENIX Security 2015)
==Notes==

- Any attack on user space in Linux could work on Windows
- If we make it easy to run Android apps on Windows OS, who would want to develop windows applications?
- Azure is already multiplatform; allowing Linux applications to run on Windows.

===Web Security Review===
- Questions to discuss:
- What is the threat model of web security?
- Who is the attacker? The defender?
- What is happening?
- An example of the attacker targeting a user is phishing (taking credentials)
- An example of the attacker targeting a web server: sending random data/traffic (ie. comment spams)
- The attacker messes with the browser through the network connection and can then run arbitrary code inside the browser
- The browser contains tokens that help access information from the web server
- The purpose of getting access to a token – impersonation
- The web in general, has a lot of depth and richness, opening up vast amounts of vulnerabilities.
- The execution of the model is strange
- Where does the web application live?
- It doesn't just live in the browser, it consists of the entire web model/mesh
- It's distributed
- Not every entity of the model is trusted
- All these web applications are running on the same system, but each have API's that allow them to connect to the rest of the world
- The design of the model is convoluted
- Web security is complex because of web browsers
- Web browsers weren't initially designed for a shared environment that executes a large variety of applications
- Because of all the interactions the browser allows, it affects the security of everything in the infrastructure.
===Cookies===
- It's data that contains the state of the user or session
- Efforts to delete the cookies every so often can be useful, but can reduce security
- Cookies are used to mark your browser as special or known
- Professor suggests using a different browser configuration for banking related activities
- Firefox allows you to setup different configurations through profiles, which have their own cookie stores, history, etc.
- Just because a browser, such as Chrome, is sandboxed, it doesn't mean that it's secure. Cookies stores are still shared
- Cookie stores are little file systems, but with not high integrity
- Cookies belong to domain names -> You can specific general domain names or specific routes
- Domain names can be bad if you're connecting to untrusted networks
- DNS is a distributed database for mapping host names to IP addresses
- Example:
- Accessing 'scs.carleton.ca'
- Find who has authority for 'ca' -> then for Carleton -> then for scs
- Going through different systems to find names, there's also no cryptographic protection against DNS (There are a lot of attacks that can fake it)
- Networks at Starbucks intercept the DNS. Splash page pops up when visiting a site. DNSSEC can be used to mitigate against it, but not used often.
- Everything depends on DNS. If tampered with, everything breaks.
- Cookies are insecure because DNS is insecure
- You can hijack cookies because you can mess with DNS

===Protocols===
- Browsers don't distinguish well between HTTP and HTTPS, therefore not guaranteeing a secured connection over HTTPS.
- Why do we use cookies? Why do we authenticate tokens?
- HTTP was designed to be stateless, but we then wanted to have states
- Technical standards aren't always better. Ie. Local Storage for cookies
- You keep things secure by isolating them
- Lack of isolation for functional purposes – People want to do things
- HSTS
- Not really a new protocol
- Enforces access over HTTPS
- If not HTTPS, don't trust
- It's because some web applications use both HTTP and HTTPS. The HTTPS downgrades to HTTP. HSTS won't let it talk to the page.
- Downgrade attack:
- Connection isn't encrypted at all
- Very easy to intercept (Man in the middle attack) instead of breaking encryption

===Some Types of Attacks===
- Cross-Site Scripting (XSS)
- Untrusted data inserted into the page
- Cross-Site Request Forgery (CSRF)
- Impersonation
- Sending unauthorized requests
- Using JSON to attack
- SOP not implemented for JSON markup files
- It executes into an object; you gain a reference to it
- You can override the array prototype methods to leak it
- Doesn't work anymore, clean JS environment is used to parse the JSON

===Paper: The Unexpected Dangers of Dynamic JavaScript===
- Paper is about loading JS script files from target websites into attacker's web application to gain access to sensitive data
- Gain access to JS file by guessing location of the script
- Once the JS script file is loaded, properties of JS such as global variables, scoping, prototype inheritance with method overwriting can be used to access the sensitive data
- How to mitigate against it?
- Don't keep sensitive data in dynamic JS files, keep it in the static files

===Paper: Cookies Lack Integrity: Real-World Implications===
- In general, this paper is hard to keep track of
- Web security in general, is very tough to handle in contrast to OS security where we have reference monitors and policies. Web security does contain similar elements, but they are scattered
- The web is a bit is like a distributed OS in the sense that we know how to scale it, predict behavior, but don't have security guarantees
===How to solve web security?===
- How would you architect it?
- Perhaps isolate applications to domains
- Have a trusted browser as the reference monitor
- Make the browser as minimal as possible
- Get rid of the DOM and JS; instead have some mediary format
- Every website can reqest a particular running environment by using hashes.
- Secure web security would essentially break the entire revenue model of the web - advertising.
===ASM.JS===
- A subset language of JS that allows arbitrary code to be compiled to JS with assembly-like speed.
- Still have all the protection that JS would have
- Problem:
- People would start running all kinds of code in the browser that isn't designed for the web
- Arbitrary environments
- Whole new class of exploits

Computer Systems Security (Winter 2016)

2016-04-05T18:17:14Z

Hammadasad: /* Lectures and Exams */

==Course Outline==

[[Computer Systems Security: Winter 2016 Course Outline|Here]] is the course outline.

==Hacking Opportunities==

The [[SystemsSec 2016W Hacking Opportunities|Hacking Opportunities]] page lists potential hacking opportunities that you can attempt for your hacking journal. If you attempt but do not successfully accomplish one of them, be sure to document what you tried. As you learn more, you may come back to them and try again.

==Resources==

===Readings===

* For the first part of the course we will be reading selections from Trent Jaeger's [http://www.morganclaypool.com/doi/abs/10.2200/S00126ED1V01Y200808SPT001 Operating Systems Security] textbook. You can download the PDF [http://www.morganclaypool.com.proxy.library.carleton.ca/doi/abs/10.2200/S00126ED1V01Y200808SPT001 through Carleton's library]. In the reading assignments this text will be referred to as "Jaeger".
* An excellent but dated text on browser security is Michal Zalewski's [https://code.google.com/p/browsersec/wiki/Main Browser Security Handbook].

===Other Courses===

* Dan Boneh ran an excellent course at Stanford in Spring 2015 on [https://crypto.stanford.edu/cs155/ Computer and Network Security]. This course has many interesting readings that we will not be covering. Also, the assignments are very good sources for hacking opportunities.
* The assignments from the Winter 2015 run of COMP 4108 [https://ccsl.carleton.ca/~dmccarney/COMP4108/ are available]. They are a reasonable start for several hacking opportunities.

==Lectures and Exams==

<table style="width: 100%;" border="1" cellpadding="4" cellspacing="0">
<tr valign="top">
<th>
Date
</th>
<th>
Topic
</th>
<th>
Readings
</th>
</tr>
<tr>
<td>
Jan. 7

</td>
<td>
[[SystemsSec 2016W Lecture 1|Introduction]]

</td>
<td>Jaeger, Chapter 1 (Introduction)</td></tr>
<tr>
<td>
Jan. 12

</td>
<td>
[[SystemsSec 2016W Lecture 2|Access Control, Security Hacking 101]]

</td>
<td>Jaeger, Chapter 2 (Access Control Fundamentals)</td></tr>
<tr>
<td>
Jan. 14

</td>
<td>
[[SystemsSec 2016W Lecture 3|Multics, UNIX, and Windows]]

</td>
<td>Jaeger, Chapter 3 (Multics) and Chapter 4 (UNIX & Windows) </td></tr>
<tr>
<td>
Jan. 19

</td>
<td>
[[SystemsSec 2016W Lecture 4|Secure OSs, theory and practice]]

</td>
<td>Jaeger, Chapter 6 (Security Kernels) and Chapter 7 (Securing Commercial Operating Systems)</td></tr>
<tr>
<td>
Jan. 21

</td>
<td>
[[SystemsSec 2016W Lecture 5|LSM, SELinux, & Capabilities]]

</td>
<td>Jaeger, Chapter 9 (LSM & SELinux) and Chapter 10 (Secure Capability Systems)</td></tr>
<tr>
<td>
Jan. 26

</td>
<td>
[[SystemsSec 2016W Lecture 6|Secure Virtual Machines, Systems Assurance]]

</td>
<td>Jaeger, Chapter 11 (Secure Virtual Machine Systems) and Chapter 12 (System Assurance)</td></tr>
<tr>
<td>
Jan. 28

</td>
<td>
[[SystemsSec 2016W Lecture 7|Lecture 7]]

</td>
<td></td></tr>
<tr>
<td>
Feb. 2

</td>
<td>
[[SystemsSec 2016W Lecture 8|Lecture 8]]

</td>
<td></td></tr>
<tr>
<td>
Feb. 4

</td>
<td>
[[SystemsSec 2016W Lecture 9|Defensive Security Technologies / Hacking Opportunities]]

</td>
<td></td></tr>
<tr>
<td>
Feb. 9

</td>
<td>
[[SystemsSec 2016W Lecture 10|Security Research, Hashes, and Secure Protocols]]

</td>
<td></td></tr>
<tr>
<td>
Feb. 11

</td>
<td>
[[SystemsSec 2016W Lecture 11|Modeling a potential attack/ Midterm FAQ]]

</td>
<td></td></tr>
<tr>
<td>
Feb. 23

</td>
<td>
[[SystemsSec 2016W Lecture 12|Midterm Review]]

</td>
<td></td></tr>
<tr>
<td>
Feb. 25

</td>
<td>
Midterm (in class)

</td>
<td></td></tr>
<tr>
<td>
Mar. 1

</td>
<td>
[[SystemsSec 2016W Lecture 13|Buffer Overflow/Memory Corruption Attacks]]

</td>
<td>Aleph One (aka Elias Levy), [http://www.phrack.com/issues/49/14.html#article Smashing The Stack For Fun And Profit] (Phrack 49, 1996)</td></tr>
<tr>
<td>
Mar. 3

</td>
<td>
[[SystemsSec 2016W Lecture 14|Buffer Overflow/Memory Corruption Defenses]]

</td>
<td>
Wikipedia, [https://en.wikipedia.org/wiki/Buffer_overflow_protection Buffer Overflow Protection] 
Crispin Cowan et al., [https://www.usenix.org/legacy/publications/library/proceedings/sec98/cowan.html StackGuard: Automatic Adaptive Detection and Prevention of Buffer-Overflow Attacks] (USENIX Security, 1998)
</td>
</tr>
<tr>
<td>
Mar. 8

</td>
<td>
[[SystemsSec 2016W Lecture 15|Bypassing ASLR and Buffer Overflow Exploits using return-into-libc]]

</td>
<td>Hovav Shacham et al., [http://dx.doi.org/10.1145/1030083.1030124 On the effectiveness of address-space randomization] (ACM CCS, 2004) [http://dl.acm.org.proxy.library.carleton.ca/ft_gateway.cfm?id=1030124&ftid=285463&dwn=1&CFID=588127386&CFTOKEN=74533951 (proxy)] 
Hovav Shachem [http://dx.doi.org/10.1145/1315245.1315313 The geometry of innocent flesh on the bone: return-into-libc without function calls (on the x86)] (ACM CCS 2007) [http://dl.acm.org.proxy.library.carleton.ca/ft_gateway.cfm?id=1315313&ftid=476749&dwn=1&CFID=588127386&CFTOKEN=74533951 (proxy)]</td></tr>
<tr>
<td>
Mar. 10

</td>
<td>
[[SystemsSec 2016W Lecture 16|Lecture 16]]

</td>
<td>Bellovin and Cheswick, [http://dx.doi.org/10.1109/35.312843 Network Firewalls] (IEEE Communications Magazine, 1994) [http://ieeexplore.ieee.org.proxy.library.carleton.ca/stamp/stamp.jsp?tp=&arnumber=312843 (proxy)]</td></tr>
<tr>
<td>
Mar. 15

</td>
<td>
[[SystemsSec 2016W Lecture 17|Lecture 17]]

</td>
<td>Dingledine, Mathewson, and Syverson, [https://www.usenix.org/legacy/events/sec04/tech/dingledine.html Tor: The Second-Generation Onion Router] (USENIX Security 2004) Albert Kwon et al., [https://www.usenix.org/conference/usenixsecurity15/technical-sessions/presentation/kwon Circuit Fingerprinting Attacks: Passive Deanonymization of Tor Hidden Services] (USENIX Security 2015) (background)[https://www.torproject.org/about/overview.html.en Tor: Overview]</td></tr>
<tr>
<td>
Mar. 17

</td>
<td>
[[SystemsSec 2016W Lecture 18|Lecture 18]]

</td>
<td>Blase Ur et al., [https://www.usenix.org/conference/usenixsecurity15/technical-sessions/presentation/ur Measuring Real-World Accuracies and Biases in Modeling Password Guessability] (USENIX Security 2015) 
Nikolaos Karapanos et al., [https://www.usenix.org/conference/usenixsecurity15/technical-sessions/presentation/karapanos Sound-Proof: Usable Two-Factor Authentication Based on Ambient Sound] (USENIX Security 2015)</td></tr>
<tr>
<td>
Mar. 22

</td>
<td>
[[SystemsSec 2016W Lecture 19|Lecture 19]]

</td>
<td>Giancarlo Pellegrino et al., [https://www.usenix.org/conference/usenixsecurity15/technical-sessions/presentation/pellegrino In the Compression Hornet’s Nest: A Security Study of Data Compression in Network Services] (USENIX Security 2015) Ramya Jayaram Masti et al., [https://www.usenix.org/conference/usenixsecurity15/technical-sessions/presentation/masti Thermal Covert Channels on Multi-core Platforms] (USENIX Security 2015)</td></tr>
<tr>
<td>
Mar. 24

</td>
<td>
[[SystemsSec 2016W Lecture 20|DDoS and Pinning]]

</td>
<td>Seyed K. Fayaz et al., [https://www.usenix.org/conference/usenixsecurity15/technical-sessions/presentation/fayaz Bohatei: Flexible and Elastic DDoS Defense] (USENIX Security 2015) Marten Oltrogge and Yasemin Acar, [https://www.usenix.org/conference/usenixsecurity15/technical-sessions/presentation/oltrogge To Pin or Not to Pin—Helping App Developers Bullet Proof Their TLS Connections] (USENIX Security 2015)</td></tr>
<tr>
<td>
Mar. 29

</td>
<td>
[[SystemsSec 2016W Lecture 21|Lecture 21]]

</td>
<td>David A. Ramos and Dawson Engler, [https://www.usenix.org/conference/usenixsecurity15/technical-sessions/presentation/ramos Under-Constrained Symbolic Execution: Correctness Checking for Real Code] (USENIX Security 2015) Nav Jagpal et al., [https://www.usenix.org/conference/usenixsecurity15/technical-sessions/presentation/jagpal Trends and Lessons from Three Years Fighting Malicious Extensions] (USENIX Security 2015)</td></tr>
<tr>
<td>
Mar. 31

</td>
<td>
[[SystemsSec 2016W Lecture 22|Cookie Integrity and XSSI]]

</td>
<td>Xiaofeng Zheng et al., [https://www.usenix.org/conference/usenixsecurity15/technical-sessions/presentation/zheng Cookies Lack Integrity: Real-World Implications] (USENIX Security 2015) Sebastian Lekies et al., [https://www.usenix.org/conference/usenixsecurity15/technical-sessions/presentation/lekies The Unexpected Dangers of Dynamic JavaScript] (USENIX Security 2015)</td></tr>
<tr>
<td>
Apr. 5

</td>
<td>
[[SystemsSec 2016W Lecture 23|Lecture 23]]

</td>
<td>Michael Backes et al., [https://www.usenix.org/conference/usenixsecurity15/technical-sessions/presentation/backes Boxify: Full-fledged App Sandboxing for Stock Android] (USENIX Security 2015) Primal Wijesekera et al., [https://www.usenix.org/conference/usenixsecurity15/technical-sessions/presentation/wijesekera Android Permissions Remystified: A Field Study on Contextual Integrity] (USENIX Security 2015)</td></tr>
<tr>
<td>
April 7

</td>
<td>
[[SystemsSec 2016W Lecture 24|Lecture 24]]

</td>
<td></td></tr>
<tr>
<td>
April 18, 10 AM-12 PM

</td>
<td>
Last-Minute Study Session

</td>
<td></td></tr>
<tr>
<td>
April 19, 9 AM

</td>
<td>
Final Exam

</td>
<td></td></tr>
</table>

==Lecture Notes Guidelines==

Part of your participation mark is doing notes for at least one of the lectures. Here are the guidelines for those notes.

The class TA Borke (BorkeObadaObieh at cmail.carleton.ca) will be handling course notes. Please contact her to schedule your class to take notes.

Borke or Anil will set you up with an account on this wiki. You'll enter your initial draft notes here and then work with Borke to make sure they are of sufficient quality. This may require a few rounds of revisions; however, if you follow the guidelines below it shouldn't be too bad.

You should plan on organizing your notes as follows:
* Organize them in at least the following sections: Topics & Readings and Notes.
* The Topics & Readings section lists the main topics covered in the class, e.g. "buffer overflows". Please use an unordered bulleted list (using *'s in wiki markup). In this section also list readings relevant to the lecture that were mentioned in class.
* Put your notes in the Notes section.

Use (nested) lists if appropriate for the notes; however, please have some text that isn't bulleted. Please try to make the notes even if you did not attend lecture; however, you don't need to cover every small bit of information that was covered. In particular the notes do not need to include digressions into topics only tangentially related to the course. Complete sentences are welcome but not required.

==Security Reading Analysis Guidelines==

A security reading analysis is a detailed analysis of a security research paper. In it you analyze the key arguments of the paper and give your informed opinion.

Most security papers can be classified as attack or defense papers. You should analyze them differently.

For attack papers:
* What systems are vulnerable to the attack?
* What is the nature of the vulnerability?
* What is the the exploit? In particular, what is its technical core?
* How reproducible is the exploit?
* Are there likely to be many similar exploits, in the targeted system or other systems?
* How difficult will it be mitigate/fix the vulnerability in targeted systems?

For defense papers:
* What is the security problem the paper addresses? In what kind of threat model(s) does the problem exist?
* How significant is the problem? Specifically, to what degree do existing solutions not work sufficiently well?
* What is the defense? How does it work?
* To what degree will the defense potentially solve the targeted security problem? In particular, how difficult will it be for attackers to adapt to this defense?
* What are the challenges facing deployment of the defense? Are they likely to be overcome?

For both kinds of papers, you should give your reaction by addressing questions like the following:
* Did you like the paper?
* Was it easy to understand, or was it hard to read?
* Did you learn much from the paper?
* How surprised were you by the result?

Your analysis should not cover the above questions separately (this would tend to make for a very wordy analysis); instead, use these questions as a guide in writing a short essay (1-2 pages) on the paper in question.

Each analysis will be graded out of 10 as follows:
* U: 3 for demonstrating understanding of the content (preferably without summarizing)
* T: 3 for technical analysis (does it work)
* C: 3 for contextual analysis (does it matter)
* V: 1 for your viewpoint

SystemsSec 2016W Lecture 22

2016-04-05T18:11:52Z

Hammadasad:

==Topics and Readings==
*Cookies And Integrity
**Xiaofeng Zheng et al., ''[https://www.usenix.org/conference/usenixsecurity15/technical-sessions/presentation/zheng Cookies Lack Integrity: Real-World Implications]'' (USENIX Security 2015)
*JavaScript Injection
**Sebastian Lekies et al., ''[https://www.usenix.org/conference/usenixsecurity15/technical-sessions/presentation/lekies The Unexpected Dangers of Dynamic JavaScript]'' (USENIX Security 2015)
== ==

- Any attack on user space in Linux could work on Windows
- If we make it easy to run Android apps on Windows OS, who would want to develop windows applications?
- Azure is already multiplatform; allowing Linux applications to run on Windows.

- Web Security Review:
- Questions to discuss:
- What is the threat model of web security?
- Who is the attacker? The defender?
- What is happening?
- An example of the attacker targeting a user is phishing (taking credentials)
- An example of the attacker targeting a web server: sending random data/traffic (ie. comment spams)
- The attacker messes with the browser through the network connection and can then run arbitrary code inside the browser
- The browser contains tokens that help access information from the web server
- The purpose of getting access to a token – impersonation
- The web in general, has a lot of depth and richness, opening up vast amounts of vulnerabilities.
- The execution of the model is strange
- Where does the web application live?
- It doesn't just live in the browser, it consists of the entire web model/mesh
- It's distributed
- Not every entity of the model is trusted
- All these web applications are running on the same system, but each have API's that allow them to connect to the rest of the world
- The design of the model is convoluted
- Web security is complex because of web browsers
- Web browsers weren't initially designed for a shared environment that executes a large variety of applications
- Because of all the interactions the browser allows, it affects the security of everything in the infrastructure.
- Cookies
- It's data that contains the state of the user or session
- Efforts to delete the cookies every so often can be useful, but can reduce security
- Cookies are used to mark your browser as special or known
- Professor suggests using a different browser configuration for banking related activities
- Firefox allows you to setup different configurations through profiles, which have their own cookie stores, history, etc.
- Just because a browser, such as Chrome, is sandboxed, it doesn't mean that it's secure. Cookies stores are still shared
- Cookie stores are little file systems, but with not high integrity
- Cookies belong to domain names -> You can specific general domain names or specific routes
- Domain names can be bad if you're connecting to untrusted networks
- DNS is a distributed database for mapping host names to IP addresses
- Example:
- Accessing 'scs.carleton.ca'
- Find who has authority for 'ca' -> then for Carleton -> then for scs
- Going through different systems to find names, there's also no cryptographic protection against DNS (There are a lot of attacks that can fake it)
- Networks at Starbucks intercept the DNS. Splash page pops up when visiting a site. DNSSEC can be used to mitigate against it, but not used often.
- Everything depends on DNS. If tampered with, everything breaks.
- Cookies are insecure because DNS is insecure
- You can hijack cookies because you can mess with DNS

- Protocols
- Browsers don't distinguish well between HTTP and HTTPS, therefore not guaranteeing a secured connection over HTTPS.
- Why do we use cookies? Why do we authenticate tokens?
- HTTP was designed to be stateless, but we then wanted to have states
- Technical standards aren't always better. Ie. Local Storage for cookies
- You keep things secure by isolating them
- Lack of isolation for functional purposes – People want to do things
- HSTS
- Not really a new protocol
- Enforces access over HTTPS
- If not HTTPS, don't trust
- It's because some web applications use both HTTP and HTTPS. The HTTPS downgrades to HTTP. HSTS won't let it talk to the page.
- Downgrade attack:
- Connection isn't encrypted at all
- Very easy to intercept (Man in the middle attack) instead of breaking encryption

-
- Some Types of Attacks
- Cross-Site Scripting (XSS)
- Untrusted data inserted into the page
- Cross-Site Request Forgery (CSRF)
- Impersonation
- Sending unauthorized requests
- Using JSON to attack
- SOP not implemented for JSON markup files
- It executes into an object; you gain a reference to it
- You can override the array prototype methods to leak it
- Doesn't work anymore, clean JS environment is used to parse the JSON
- Paper: The Unexpected Dangers of Dynamic JavaScript
- Paper is about loading JS script files from target websites into attacker's web application to gain access to sensitive data
- Gain access to JS file by guessing location of the script
- Once the JS script file is loaded, properties of JS such as global variables, scoping, prototype inheritance with method overwriting can be used to access the sensitive data
- How to mitigate against it?
- Don't keep sensitive data in dynamic JS files, keep it in the static files
- Paper: Cookies Lack Integrity: Real-World Implications
- In general, this paper is hard to keep track of
- Web security in general, is very tough to handle in contrast to OS security where we have reference monitors and policies. Web security does contain similar elements, but they are scattered
- The web is a bit is like a distributed OS in the sense that we know how to scale it, predict behavior, but don't have security guarantees
- How to solve web security? How would you architect it?
- Perhaps isolate applications to domains
- Have a trusted browser as the reference monitor
- Make the browser as minimal as possible
- Get rid of the DOM and JS; instead have some mediary format
- Every website can reqest a particular running environment by using hashes.
- Secure web security would essentially break the entire revenue model of the web - advertising.
- ASM.JS
- A subset language of JS that allows arbitrary code to be compiled to JS with assembly-like speed.
- Still have all the protection that JS would have
- Problem:
- People would start running all kinds of code in the browser that isn't designed for the web
- Arbitrary environments
- Whole new class of exploits

SystemsSec 2016W Lecture 22

2016-04-01T21:12:55Z

Hammadasad: Created page with "- Any attack on user space in Linux could work on Windows - If we make it easy to run Android apps on Windows OS, who would want to develop windows applications? - Azure is al..."

- Any attack on user space in Linux could work on Windows
- If we make it easy to run Android apps on Windows OS, who would want to develop windows applications?
- Azure is already multiplatform; allowing Linux applications to run on Windows.

- Web Security Review:
- Questions to discuss:
- What is the threat model of web security?
- Who is the attacker? The defender?
- What is happening?
- An example of the attacker targeting a user is phishing (taking credentials)
- An example of the attacker targeting a web server: sending random data/traffic (ie. comment spams)
- The attacker messes with the browser through the network connection and can then run arbitrary code inside the browser
- The browser contains tokens that help access information from the web server
- The purpose of getting access to a token – impersonation
- The web in general, has a lot of depth and richness, opening up vast amounts of vulnerabilities.
- The execution of the model is strange
- Where does the web application live?
- It doesn't just live in the browser, it consists of the entire web model/mesh
- It's distributed
- Not every entity of the model is trusted
- All these web applications are running on the same system, but each have API's that allow them to connect to the rest of the world
- The design of the model is convoluted
- Web security is complex because of web browsers
- Web browsers weren't initially designed for a shared environment that executes a large variety of applications
- Because of all the interactions the browser allows, it affects the security of everything in the infrastructure.
- Cookies
- It's data that contains the state of the user or session
- Efforts to delete the cookies every so often can be useful, but can reduce security
- Cookies are used to mark your browser as special or known
- Professor suggests using a different browser configuration for banking related activities
- Firefox allows you to setup different configurations through profiles, which have their own cookie stores, history, etc.
- Just because a browser, such as Chrome, is sandboxed, it doesn't mean that it's secure. Cookies stores are still shared
- Cookie stores are little file systems, but with not high integrity
- Cookies belong to domain names -> You can specific general domain names or specific routes
- Domain names can be bad if you're connecting to untrusted networks
- DNS is a distributed database for mapping host names to IP addresses
- Example:
- Accessing 'scs.carleton.ca'
- Find who has authority for 'ca' -> then for Carleton -> then for scs
- Going through different systems to find names, there's also no cryptographic protection against DNS (There are a lot of attacks that can fake it)
- Networks at Starbucks intercept the DNS. Splash page pops up when visiting a site. DNSSEC can be used to mitigate against it, but not used often.
- Everything depends on DNS. If tampered with, everything breaks.
- Cookies are insecure because DNS is insecure
- You can hijack cookies because you can mess with DNS

- Protocols
- Browsers don't distinguish well between HTTP and HTTPS, therefore not guaranteeing a secured connection over HTTPS.
- Why do we use cookies? Why do we authenticate tokens?
- HTTP was designed to be stateless, but we then wanted to have states
- Technical standards aren't always better. Ie. Local Storage for cookies
- You keep things secure by isolating them
- Lack of isolation for functional purposes – People want to do things
- HSTS
- Not really a new protocol
- Enforces access over HTTPS
- If not HTTPS, don't trust
- It's because some web applications use both HTTP and HTTPS. The HTTPS downgrades to HTTP. HSTS won't let it talk to the page.
- Downgrade attack:
- Connection isn't encrypted at all
- Very easy to intercept (Man in the middle attack) instead of breaking encryption

-
- Some Types of Attacks
- Cross-Site Scripting (XSS)
- Untrusted data inserted into the page
- Cross-Site Request Forgery (CSRF)
- Impersonation
- Sending unauthorized requests
- Using JSON to attack
- SOP not implemented for JSON markup files
- It executes into an object; you gain a reference to it
- You can override the array prototype methods to leak it
- Doesn't work anymore, clean JS environment is used to parse the JSON
- Paper: The Unexpected Dangers of Dynamic JavaScript
- Paper is about loading JS script files from target websites into attacker's web application to gain access to sensitive data
- Gain access to JS file by guessing location of the script
- Once the JS script file is loaded, properties of JS such as global variables, scoping, prototype inheritance with method overwriting can be used to access the sensitive data
- How to mitigate against it?
- Don't keep sensitive data in dynamic JS files, keep it in the static files
- Paper: Cookies Lack Integrity: Real-World Implications
- In general, this paper is hard to keep track of
- Web security in general, is very tough to handle in contrast to OS security where we have reference monitors and policies. Web security does contain similar elements, but they are scattered
- The web is a bit is like a distributed OS in the sense that we know how to scale it, predict behavior, but don't have security guarantees
- How to solve web security? How would you architect it?
- Perhaps isolate applications to domains
- Have a trusted browser as the reference monitor
- Make the browser as minimal as possible
- Get rid of the DOM and JS; instead have some mediary format
- Every website can reqest a particular running environment by using hashes.
- Secure web security would essentially break the entire revenue model of the web - advertising.
- ASM.JS
- A subset language of JS that allows arbitrary code to be compiled to JS with assembly-like speed.
- Still have all the protection that JS would have
- Problem:
- People would start running all kinds of code in the browser that isn't designed for the web
- Arbitrary environments
- Whole new class of exploits