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URL Obscuring COEN 152/252 Computer Forensics Thomas Schwarz, S.J. 2004

URL Obscuring COEN 152/252 Computer Forensics Thomas Schwarz, S.J. 2004

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Text of URL Obscuring COEN 152/252 Computer Forensics Thomas Schwarz, S.J. 2004

  • Slide 1
  • URL Obscuring COEN 152/252 Computer Forensics Thomas Schwarz, S.J. 2004
  • Slide 2
  • URL Obscuring Internet based fraud is gaining quickly in importance. Phishing: The practice of enticing victims with spoofed email to visit a fraudulent webpage. http://www.antiphishing.org/ Graphics courtesy of Tumbleweed Communications
  • Slide 3
  • URL Obscuring Target receives e-mail pretending to be from an institution inviting to go to the institutions website. Following the link leads to a spoofed website, which gathers data. It is possible to establish a web-presence without any links: Establish website with stolen / gift credit card. Use email to send harvested information to an untraceable account, etc. Connect through public networks.
  • Slide 4
  • URL Obscuring: Phishing Example Visible Link: https://www.usa.visa.com/personal/secure_with_visa/index.html?t=h1_/index.html Actual Link: http://www.verified-web-us.com/Visa%20USA%20%20Personal%20%20Protect%20Your%20Card.htm Actual website IP: Uses Java program to overwrite the visible address bar in the window:
  • Slide 5
  • URL Obscuring: Phishing Example
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  • URL Obscuring Phishs need to hide web-servers URL Obscuring Javascript or other active web-technology overwrites URL field Other techniques to hide web-server address Use hosts file Hiding illegal web-server at legal site
  • Slide 7
  • URL Basics Phishs can use obscure features of URL. URL consists of three parts: Service Address of server Location of resource. http://www.cse.scu.edu/~tschwarz/coen252_03/Lectures/URLObscuring.html
  • Slide 8
  • URL Basics Scheme, colon double forward slash. An optional user name and password. The internet domain name RCF1037 format IP address as a set of four decimal digits. Port number in decimal notation. (Optional) Path + communication data. http://tschwarz:[email protected]/~tschwarz/coen252_03/Lectures/URLObscuring.html http://www.google.com/search?hl=en&ie=UTF-8&q=phishing
  • Slide 9
  • Obscuring URL Addresses Embed URL in other documents Use features in those documents to not show complete URL http://[email protected]/~tschwarz/coen252_03/index.html URL rules interpret this as a userid. Hide this portion of the URL.
  • Slide 10
  • Obscuring URL Addresses Use the password field. www.scu.edu has IP address Some browsers accept the decimal value 129*256**3 + 210*256**2 + 2*256 + 1 = 2178023937 for the IP address. http://[email protected] Works as a link. Does not work directly in later versions of IE
  • Slide 11
  • Obscuring URL Addresses http://[email protected] works. Hide the ASCI encoding of @: http://www.usfca.edu%40129.210.2.1 Or just break up the name: http://www.usfca.edu%40%127%167w.scu.edu Or use active page technologies (javascript, ) to create fake links.
  • Slide 12
  • 'Enroll your card with Verified By Visa program' 2004 Phish sends SPAM consisting of a single image:
  • Slide 13
  • 'Enroll your card with Verified By Visa program' The whole text is a single image, linked to the correct citi URL. If the mouse hovers over the image, it displays the correct citi URL. But surrounded by an HTML box that leads to the phishing website.
  • Slide 14
  • 'Enroll your card with Verified By Visa program' Target webpage has an address bar that is overwritten with a picture with a different URL. Go to www.antiphishing.org.
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  • Slide 17
  • Hiding Hosts Name Look-Up: OS checks HOST file first. Can use HOST file to block out certain sites adservers Affects a single machine. OSLocation Linux/etc/hosts Win95/98/MEC:\windows\hosts Win NT/2000/XP ProC:\winnt\systems32\etc\hosts Win XP HomeC:\windows\system32\drivers\etc\hosts
  • Slide 18
  • Subverting IP Look-Up In general, not used for phishing. Economic Damage Hillary for Senate campaign attack. Hiding illegal websites. (Kiddie Porn) DNS Server Sabotage IP Forwarding
  • Slide 19
  • Subverting IP Look-Up Port Forwarding URLs allow port numbers. Legitimate business at default port number. Illegitimate at an obscure port number. Screen clicks Embed small picture. Single pixel. Forward from picture to the illegitimate site. Easily detected in HTML source code. Password screens Depending on access control, access to different sites.
  • Slide 20
  • Phisher-Finder Carefully investigate the message to find the URL. Do not expect this to be successful unless the phisher is low-tech. Capture network traffic with Ethereal to find the actual URL / IP address. Use Sam Spade or similar tools to collect data about the IP address.
  • Slide 21
  • Phisher-Finder Capture network traffic with Ethereal when going to the site. This could be dangerous. Disable active webpages. Do not use IE (too popular). Look at the http messages actually transmitted. Expect some cgi etc. script.
  • Slide 22
  • Phisher-Finder Investigation now needs to find the person that has access to the website. This is were you can expect to loose the trace. The data entered can be transmitted in various forms, such as anonymous email. For example, they can be sent to a free email account. IPS usually has the IP data of the computer from which the account was set up and from which the account was recently accessed. Perpetrator can use publicly available computers and / or unencrypted wireless access points. Investigator is usually left with vague geographical data.