1. Presentation By :- ADARSH PILLAY
An Empirical Evaluation of Security Indicators in Mobile Web Browsers Chaitrali Amrutkar, Patrick Traynow and Paul C. van Oorschot
Presentation By :- ADARSH PILLAY

2. OVERVIEW
Security Indicators are those elements which give an indication of whether something is secure or not web page is, in context of web browsing.
Security sensitive operations are not only restricted to desktop rather now mobile browsers are also increasingly being relied upon.
W3C has set forth some guidelines to convey security for web user interface.
Experiments are performed on popular browsers both on mobile and desktop and comparison is being made.

3. CONTENT Section 1 Section 2 Section 3 Section 4 Section 5 Section 6
Introduction
Section 2
W3C Terminologies and Guidelines
Section 3
Observations of Results
Section 4
Additional Results
Section 5
User’s interaction and Possible attacks
Section 6
Related Work
Section 7
Concluding Remarks
CONTENT

4. INTRODUCTION
Users are increasingly getting reliable on mobile devices for sensitive personal, social & financial exchanges.
But the users are getting attacked even after browsers have strong cryptographic tools and the reason for this is not immediately clear.
Goal is to check whether applied security indicators allows expert users to accurately determine the identity of website.
The attacks are of different types like phishing, man-in-the-middle. Also, EV-SSL indicators are missing in the mobile browsers.

5. W3C TERMINOLOGIES User Interface Elements Trust Anchor Root
Trusted Root
Certificates
Pinning
Identity Signal
Strong TLS
Weak TLS
Error Messages

6. W3C GUIDELINES Identity Signal : Availability
Certificates : Required Content
TLS Indicators
Significance of presence
Content & Indicator Proximity
Availability
Robustness : Visibility of Indicators
Error Messages
Interruption
Proceeding Options
Inhibit Interaction

7. Implementation Set Up
The Cross Marks in the tables in coming slides represent that browser doesn’t comply with the W3C Guidelines.
The Bullets in the tables in coming slides represent that browser doesn’t comply with the W3C Guidelines.

8. IDENTITY SIGNAL The Owner of the Website
The Corresponding Issuer of Certificate
Identity Signal contains information about
MUST be available to user through either of the interface at all the times

9. CERTIFICATES Certificates MUST provide Reasons of Trust
Same Website’s Domain Name
Reason of Trust
Reasons of Trust
If certificate was accepted interactively or not
If certificate was self-signed or not
If self-signed then whether presented to user or not

10. TLS INDICATORS Content and Indicator Proximity Availability
Any UI indicator MUST NOT signal the presence of a certificate unless all parts of the webpage are loaded.
If browser displays a TLS indicator for the presence of a certificate for a webpage consisting of mixed content, this guideline is not followed.
Significance of Presence
Content MUST NOT be displayed in a manner that confuses hosted content.
If a browser allows a favicon to be placed next to the padlock, an attacker can feign a secure website by mimicking the favicon as a security indicator.
Content and Indicator Proximity
The TLS Indicators must be available to the user through either of the interface at all times.
Check whether cipher details are available or not and also, if lock icon shown or not.
Availability

11. Observations of TLS Indicators on Mobile & Tablet Browsers & Desktop Browsers

12. Web content MUST NOT obscure the security user interface.
ROBUSTNESS
Web content MUST NOT obscure the security user interface.
The TLS indicators found on the user interface are lock icon, https URL prefix, URL coloring and site identity button.
The visibility of these indicators is dependent on the mode of screen whether it is landscape or portrait.

13. ERROR MESSAGES Interruption Proceeding Options Inhibit Operation
Both warning/caution and danger messages MUST interrupt the user’s current task, such that the user has to acknowledge the message.
Interruption
Warning/caution messages MUST provide the user with distinct options for how to proceed (i.e., these messages MUST NOT lead to a situation in which the only option presented to the user is to dismiss the warning and continue).
Proceeding Options
The interactions for danger messages MUST be presented in a way that makes it impossible for the user to go to or interact with the destination website that caused the danger situation to occur, without first explicitly interacting with the danger message.
Inhibit Operation

14. Observations of Error Messages on Mobile & Tablet Browsers & Desktop Browsers
Cross with star represents that browser fails to warn user according to our view.
NA implies that the particular experiment is not applicable to that browser.

15. ADDITIONAL RESULTS : POSITIVE
SSL version 2 MUST NOT hold strong and after the experiment authors found that
None of the browsers in either mobile or tablet support it.
The NULL Cipher is one of the most dangerous ciphers as it represents lack of an encrypted communication channel. Authors found that
None of the browsers either in mobile or tablet support the null cipher.

16. ADDITIONAL RESULTS : NEGATIVE
Browser supporting weak cipher can enable a network attacker to break the encrypted messages .
Observations
Authors perform check on DES-CBC-SHA weak cipher.
6 mobile & tablet browsers support weak cipher.
Others display error messages conveying absence of encryption protocol with server.

17. ADDITIONAL RESULTS : NEUTRAL
No difference between EV-SSL and SSL Certificates provided by W3C Documents.
Only sole difference from user’s perspective is that of the indicators shown in the browser.
SSL Certificates can be just domain validated only i.e. users can’t be aware whether website owner is validated or not.
SSL certificates cheaper for validation compared to EV-SSL.
In a browser with no differentiation between SSL and EV-SSL certificates, they both are same from user’s perspective.
The inconsistency across browsers from same vendor adds to an already confusing task of whether it is an EV-SSL or SSL certified website.

18. USER DECEPTION AND POSSIBLE ATTACKS
If W3C Guidelines are not followed then users can be easily misled about the identity of the website or the security of the connection.
Four types of attacks are discussed which are possible due to violation of one or more W3C Guidelines.
Phishing without SSL
Phishing with SSL
Phishing using compromised CA
Industrial Espionage

19. PHISHING WITHOUT SSL A Cross implies that an attack is possible.
Attacker masquerades as a trustworthy entity in the attack as closely imitates the legitimate website’s identity along with lock icon spoofing, launching attack without SSL on browser.
Domain name quite similar to legitimate website which provides an impression of correct identity of website.
Makes the favicon a lock image which provides an illusion for strong encryption.
When rendered in a browser where URL viewing is difficult or doesn’t offer a UI to view identity information of website, then even advance user might get subjected to phishing.
PHISHING WITHOUT
SSL
A Cross implies that an attack is possible.
A Bullet implies that the corresponding attack is not possible.

20. Spoofing only lock icon is not adequate for a successful phishing attack.
An attacker can buy an inexpensive SSL Certificate for website to increase credibility of attack.
It helps as in by providing https URL prefix and URL Coloring option in addition to lock icon.
Thus, if user blindly trusts these indicators then it will be subjected to phishing attack.
PHISHING WITH SSL

21. PHISHING USING COMPROMISED CA
Attacker obtains rogue certificates for legitimate websites by compromising CA.
If a browser trusts a CA then it doesn’t checks if CA is compromised or not.
An expert user can verify certificate issuer’s organization in the chain, thus not interacting with malicious website having a rogue certificate.
But if browser doesn’t allow user interface to have certificate viewing, then even an expert user can be subjected to phishing attack.

22. INDUSTRIAL ESPIONAGE/EAVESDROPPING
SSLstrip Attack
Attacker sits on the local network and intercepts traffic.
As attacker finds a request for an encrypted https site, it duplicates it with an unencrypted http site.
This switching strips away the security, also, deceiving the server that an encrypted page has been sent to client.
Cipher Downgrade Attack
An attacker can tamper the initial messages sent by the client to server for setting up connection.
The attacker can modify the ciphers that client and server exchange to weak ciphers and then forward it to server.
On receiving weak ciphers, server can either establish a connection or drop it.
If connection is established then, all data is transmitted through weak cipher encryption scheme & thus attacker can stream the data and break it offline.
Also an expert user can get subjected to this attack.
Mixed Content
Attacker can tamper the unencrypted content on the webpage consisting of mixed content by replacing it with malicious content of his choice.
Even expert users are unable to detect this if browser displays the SSL Indicators for a webpage containing mixed content.

23. RELATED WORK Traditional Browser Indicators
They contain a range of indicators like https prefix, lock icon etc., but generally these go unnoticed or are absent in websites.
Many users don’t understand the concept of lock icon and certificates. Also there are lot of domain name mismatches between certificates and websites.
Techniques for better indicators
Better Warnings
More effective interface dialogues
Trusted path from browser to user
Disabling JS in user browser & forcing persistent view of browser’s location
Dynamic Security Skins
Finally, efforts to standardize security indicators & thus minimize confusion across browsers.
Mobile Browser Indicators
Increasing user base of mobile web browsers and mobile e-commerce has now brought focus for attackers.
Also, having a different user interface than desktop browser makes it more important to focus on security indicators usage in mobile browsers.

24. CONCLUDING REMARKS
Modern mobile browsers depict a range of sensitive operations related to security features of web browsers.
But compared to desktop, they lack behind due to scree size issue.
Tremendous inconsistency was seen in security indicators on mobile browsers.
Also, adding of EV-SSL certificates make the mobile ecosystem more complex without producing much benefits.
Such significant changes make it difficult for expert users too, for detecting security issues, raising high concern for average users as how they will deal with it.

25. THANK YOU