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Web browser privacy and security
 

Web browser privacy and security

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Web browser privacy and security Web browser privacy and security Presentation Transcript

  • Web browser privacy and security (I) March 21 st , 2006 Ricardo Villamarin-Salomon
  • Outline
    • Web Browser In security
    • Informed Consent by Design
    • Hardening Web Browsers Against Man in the Middle and Eavesdropping Attacks
    • Participation
  • Web Browser Insecurity
    • Targeted attacks on Web applications and Web browsers are increasingly becoming the focal point for cyber criminals.
      • Traditional attack activity : motivated by curiosity and a desire to show off technical virtuosity
      • Current threats are motivated by profit: identity theft, extortion, and fraud, for financial gain.
  • Source : secunia.com Date: 2006-March-19 Original Idea : ZDNet.com Revision & Update (March 2006) : me Worry-free web?
  • Web Browser vulnerabilities, vendor confirmed Source: Symantec Internet Security Threat Report (Vol. IX)
  • Web Browser vulnerabilities, confirmed & non-confirmed by vendor Source: Symantec Internet Security Threat Report (Vol. IX)
  • Some Common Vulnerabilities (CERT)
    • ActiveX Controls
    • Java applets (bypassing of sandbox’s restrictions)
    • Cross-Site Scripting (mainly faults of web sites)
      • e.g, http://host.com/modules.php?op=modload&name=XForum&file= [hostilejavascript] &fid=2
    • Cross-Zone and Cross-Domain Vulnerabilities
      • Prevention of a web site from accessing data in a different domain (or zone) is broken
    • Malicious Scripting, Active Content, and HTML
    • Spoofing As it relates to web browsers, spoofing is a term used to describe methods of faking various parts of the browser user interface.
  • Informed Consent for Information Systems Batya Friedman, Peyina Lin, and Jessica K. Miller
  • Value Sensitive Design
    • Design of Information and Computer Systems that accounts for human values
    • Value Sensitive Design is an interactional theory
      • In general, we don’t view values as inherent in a given technology
      • However, we also don’t view a technology as value-neutral
      • Rather, some technologies are more suitable than others for supporting given values
    • Key task of VSD: Investigate these “value suitabilities” (along with what values and whose values)
    © Batya Friedman 2003
  • VSD’s Tripartite Methodology
    • Conceptual investigations
      • Philosophically informed analyses of the values and value conflicts involved in the system
    • Technical investigations
      • Identify existing or develop new technical mechanisms; investigate their suitability to support or not support the values we wish to further
    • Empirical investigations
      • Using techniques from the social sciences, investigate issues such as: Who are the stakeholders? Which values are important to them? How do they prioritize these values?
    • These are applied iteratively and integratively
    © Batya Friedman 2003
  • Direct and Indirect Stakeholders
    • Direct stakeholders: Interact with the system being designed and its outputs
    • Indirect stakeholders: Don’t interact directly with the system, but are affected by it in significant ways
    © Batya Friedman 2003
  • Model of Informed Consent for Information Systems
    • Disclosure
    • Comprehension
    • Voluntariness
    • Competence
    • Agreement
    • Minimal Distraction
  • NS 3.04 Cookie Warning Dialog Box
  • NS 4.03 Cookie Settings
  • IE 4.0 Cookie Warning Dialog Box
  • IE 5.0 Custom Cookie Settings
  • The Unique Role of the Web Browser
    • Browser software mediates communication between a client (typically an end user) and a server
    • After a remote site has exercised a capability, the Web browser software has no control over what the remote site does with the information or other actions that the site may take.
  • The Unique Role of the Web Browser
    • With respect to Information Consent
      • Disclosure:
        • Whether the user is notified about a server request
        • Harms / Benefits?
      • Comprehension: (to a large extent)
        • Controls the content of the notification (if any)
      • Agreement:
        • User’s opportunity to agree/decline to place a cookie (prompting)
        • Ongoing : how to withdraw from agreement (obscure locations)?
  • The Unique Role of the Web Browser
    • With respect to Information Consent
      • Minimal distraction
        • IE: acceptance/declination of third party cookies by the user (one by one)
      • Voluntariness?
        • Browser or Website?
      • Competence (cookies)?
        • Browser or Website?
  • Design Goals
    • Enhance users’ local understanding of cookie events as the events occur with minimal distraction to the user
      • Preset agreement policy that applies to all cookies of a specified type
        • Minimizes user distraction at the expense of rote decision-making, disclosure and comprehension
      • Explicitly accept or decline each cookie one at a time
        • Supports the criterion of disclosure but at the expense of extreme distraction
      • Middle ground?
  • Design Goals
    • Enhance users’ global understanding of the common uses of cookie technology
      • Including potential benefits and risks associated with those uses
      • A necessary piece of disclosure and comprehension
  • Design Goals
    • Enhance users’ ability to manage cookies
      • Particularly with respect to the easy viewing of cookie information and on-going control over the lifetime and removal of cookies.
      • Agreement is ongoing: the user had no easy means (1999 browser technology) to remove the previously set cookies and thereby revoke consent
    • Achieve design goals 1, 2 and 3 while minimizing distraction for the user
  • © Batya Friedman 2003
  • © Batya Friedman 2003
  • © Batya Friedman 2003
  • © Batya Friedman 2003
  • © Batya Friedman 2003
  •  
  •  
  • Renamed to “Cookie-Panel”
    • https://addons.mozilla.org/extensions/moreinfo.php?id=1375
    • Informing through interaction Design
    Secure Connections
  • Secure Connections: Different Evidences For a suspicious (!) site, the Address bar turns yellow and displays a warning label but still allows data entry
    • … we turn the entire address bar a bright shade of yellow at secure sites
    • It's impossible to miss;
    • the connection with the page “ is clear ” because it highlights the page address;
    • and it's “ obvious ” what it means because it's punctuated by a large lock
    • - Blake Ross ..
    Firefox IE 7 Beta
  • Secure Connections: Your opinion? Fits in the status bar (IE 6) No encryption Secure Connection (Certificate is OK) “ Secure” Connection (Problem with Certificate)
  • GMail: Questions related to Informed Consent
    • Machines reading personal content
      • … a privacy violation concerns the act of intrusion upon the self, independent of the state of mind (or knowledge) of the intruder - Edward Bloustein
      • Spam filters?
    • Indirect stakeholders
      • targeted advertisements should not be allowed without the consent of all parties involved in an email exchange. Gmail does not obtain the consent of the email sender. How?
      • Automatic reply: once (the first time) and for all make the sender agree with Gmail TOS (something similar to mailblocks.com for verifying that an email was sent by a human)
  • Hardening Web Browsers Against Man in the Middle and Eavesdropping Attacks Haidong Xia and Jose Carlos Brustoloni
  • Usability of Web Browser security
    • Man-In-The-Middle (MITM) attacks
    • Eavesdropping attacks
    • Several tools available
  • Man-In-The-Middle (MITM) attacks
    • The public keys of major CAs (e.g., Verisign) are embedded in many client applications (e.g.,Web browsers).
  • Common sources of Ct. verification failure
    • The browser may not know the public key of the CA that issued the server’s certificate
      • Internal web server (only by members of the organization)
      • Own CA: public key installed in browser (no verification errors)
      • Large number of users / User owned computer
    • Issuer’s or the server’s certificate may be expired
  • Common sources of Ct. verification failure
    • Server may have presented a certificate whose common name field does not match the server’s fully qualified domain name
      • Attacker can use his own identity with a CA generated certificate
      • Attacker may have stolen the Ct. (along with the private key)
      • Mismatches at subdomain level not very risky (unless a very sophisticated attack is mounted)
        • Allow user to proceed
      • Other cases more serious
        • Ch. 28
  • Common sources of Ct. verification failure
  • Common sources of Ct. verification failure
  • Context Sensitive Certificate Verification
    • Clarify the relationship between the user and the server’s (non verified) certificate
      • Not giving the user override mechanisms
    • Distribute signed certificates of the internal servers out of band
    • Take advantage of typically unused Ct’s fields:
      • CA’s contact information ( field: issuer alternative name )
      • CA administrator’s name, address, telephone and fax numbers, and work hours.
  • Context Sensitive Certificate Verification
  •  
  •  
  • Specific Passwords Warnings
    • Helps prevent eavesdropping
    • Allow overriding
  • Specific Passwords Warnings
  • Specific Passwords Warnings
  • User Studies
    • Computer literate users (CLU)
    • Evaluate:
      • Likelihood of successful attack in representative security-sensitive Web applications
      • Possibility of “foolproofing” web browsers, so they can be used securely even by untrained CLUs
      • Can education about the relevant security principles, attacks, and tools improve the security of how users browse the Web?
        • Note: This last hypothesis is not covered in this presentation
  • Study’s Design
    • 17 participants (majors from Pitt’s CS department)
    • Two studies:
      • Unmodified browser (IE)
      • Modified Mozilla Firebird 0.6.1 with CSCV and SPW
    • No feedback given between these two studies
  • Study’s Design
    • Visit three fictional but realistic Web sites where students were assigned password protected accounts
    • The first site: maintained by the students’ university.
      • It allows students to monitor the respective reward points (earned by doing well in exams, independent studies, etc.)
      • HTTPS + Certificate issued by internal CA
    • The second site: m. by a remote e-merchant not affiliated with U.
      • Students can spend their reward points, (e.g. to buy books, CDs, etc.)
      • HTTPS + bogus certificate
    • The third site provides access to users’ Web email accounts
      • HTTP only (no certificate)
  • Study’s Design 100 Choosing not to access to 2nd and 3rd site insecurely 100 Correctly obtained and installed the issuing CA’s certificate 50 Simply did not visit the site insecurely 0 Access to a site despite lack of security Score (points) User’s Action
  • Study’s Results
    • With current users and Web browsers, the mentioned attacks are alarmingly likely to succeed.
      • More often than not, users’ behavior defeats the existing Web security mechanisms.
    • CSCV blocked MITM attacks against HTTPS-based applications completely.
    • SPW greatly reduced the insecure transmission of passwords in an HTTP-based application
    • Although untrained, users had little trouble using CSCV and SPW.
  • Participation
  • Disagreements about Secure Connections
    • Propose some ideas for representing secure connections in web browsers
  • Thank you!